For the human body, protection against free radical damage comes in the form of powerful, natural antioxidants such as Vitamin E. The benefits to the skin and general health care of Vitamin E are numerous, and constantly being researched by health industry professionals. In terms of the skin, Vitamin E can help reduce signs of aging, protect against sun and pollutant damage, and have many other visible results.
The Sun & AgingThe blame for premature aging lies with the UVA rays produced by the sun. Ultraviolet radiation can penetrate the skin, breaking up molecules of oxygen and creating unstable free radicals. These toxic cells attack nearby cells, breaking them down into more and more free radicals, and a violent cycle of cell destruction results. Lipids, proteins, and DNA are all susceptible, leading to leathery looking skin that lacks collagen and elasticity (Vitamin and Supplement).
11/15/09
Vitamin C Can Prevent Pregnancy Complication
Women who supplement their diet with a small amount of vitamin C during the second half of pregnancy reduce their risk of one contributor to premature birth, according to the American Journal of Clinical Nutrition (2005;81:859–63).
The end of pregnancy and the beginning of the birth process is marked by rupture of the walls (membranes) of the sac that holds the growing fetus and the amniotic fluid. A healthy pregnancy usually lasts about 40 weeks. Premature birth occurs when the membranes rupture and birth begins before 37 weeks of pregnancy. Smoking, vaginal infection, and poor maternal nutrition can all increase the risk of premature rupture of the membranes (PROM). PROM occurs in 10 to 20% of pregnancies worldwide and is the most common cause of premature births. Babies born prematurely face many health risks: their underdeveloped lungs do not function properly, they are highly susceptible to infections, and they have difficulty nursing.
The end of pregnancy and the beginning of the birth process is marked by rupture of the walls (membranes) of the sac that holds the growing fetus and the amniotic fluid. A healthy pregnancy usually lasts about 40 weeks. Premature birth occurs when the membranes rupture and birth begins before 37 weeks of pregnancy. Smoking, vaginal infection, and poor maternal nutrition can all increase the risk of premature rupture of the membranes (PROM). PROM occurs in 10 to 20% of pregnancies worldwide and is the most common cause of premature births. Babies born prematurely face many health risks: their underdeveloped lungs do not function properly, they are highly susceptible to infections, and they have difficulty nursing.
Vitamins and Minerals for Healthy Blemish-Free Skin Acne Prevention Vitamins - Powerful Antioxidants
Acne is a common concern among adolescents and adults alike. No one is happy about looking in the mirror and seeing pimples and blackheads on their face glaring back at them. The ideal is to see a reflective smile along with a clear complexion and healthy glow in your cheeks.
In this article we will explore various vitamins and minerals to learn how they affect the health of your skin and hopefully help you break-free from unsightly blemishes and break-out into a beautiful radiant smile.
From a holistic point of view all illnesses are manifestations of our imbalances. In treating acne outbreaks the holistic practitioner would typically consider all emotional, physical, mental, or even spiritual imbalances. Any treatments offered would address the whole person, not just the physical body.
For example, Louise Hay, author of The New York Times best seller self-help book You Can Heal Your Life, teaches that acne is a manifestation of not loving or accepting yourself. Hays suggests this affirmation for those with acne: I am a Divine expression of life, I love and accept myself where I am right now..
Some holistic practitioners also cite poor diets and deficiencies in vitamins and minerals as factors that upset the natural internal workings of physical organs and disturb optimal blood circulation. In Ayurvedic medicine, acne (known clinically as Yauvan Pidika) is believed to be an internal constitutional disorder of the body and is caused primarily by improper diet, impurities in the blood, and imbalances in Kapha and Vata. However, there is virtually no scientific evidence linking diet to acne, and dermatologists dismiss such claims."
Vitamin Treatments for Acne
Healthy and radiant skin requires proper nutrition. However, according to a 2007 report by the Center for Disease Control and Prevention, 39.5 percent of Americans eat less than the recommended three to five servings of fruits and vegetables each day. Deficiencies in vitamins and minerals can affect the body's ability to function optimally. Vitamins and minerals can be taken to supplement our diets when our nutritional needs are lacking through food consumption alone.
However, multivitamins should not be taken as a substitute for eating healthy foods. Taking too much of any vitamin or mineral can be toxic and extremely dangerous. Please consult with a doctor or other trained healthcare professional before taking any dietary supplements.
* Vitamin A - Retinoids, derivatives of vitamin A, are used to treat acne and other skin disorders. Retinoids are prescribed by dermatologists both topically and orally. A common type of retinoid used in the oral treatment of acne is isotretinoin.
* Omega-3 Fatty Acids - Omega-3 fatty acids from fish oil, chromium, zinc, and selenium are nutrients that may have both anti-acne and mood regulating properties according to an acne study conducted at the Lasky Skin Clinic in 2008.
* Zinc - The National Library of Science recognizes that zinc may be effective in the treatment of acne based on available science evidence. The Department of Dermatology at SUNY Downstate Medical Center in New York also recognizes zinc, along with vitamin A, and tea tree oil (also ayurvedic therapies) as over-the-counter remedies available for treating acne. However, its position on these remedies is that additional and better studies are needed to clarify the benefits.
Essential Vitamins for Skin Care in General
* Vitamin A - According to Dr. Eugene S. Bereston "the therapeutic use of Vitamin A began almost with the discovery of the vitamin." Bereston also noted that the first property of vitamin A is its ability to stimulate growth. The American Academy of Dermatology reports that vitamin A is vital to the health of both your skin and your eyes. The academy recommends a daily dose of vitamin A. Examples of vitamin A enriched foods include citrus fruits, carrots, tomatoes, yellow squash, and pumpkin. Vitamin A can also be applied to the skin topically with creams to promote cell growth.
* Vitamin B - The Office of Dietary Supplements at the National Institute of Health states that inflammation of the skin is one sign of B6 deficiency. Clinical signs of vitamin B6 deficiency are rarely seen in the United States. Alcoholics and aging adults are at the highest risk for B6 deficiencies due to poor dietary habits.
* Vitamins C and E - The American Academy of Dermatology recommends daily oral dosages of vitamins C and E to protect the body and for its antioxidant properties that are important for healthy skin.
* Zinc - A study conducted at Duke University provides evidence that Zinc is an important antioxidant supporting healthy skin. Among the findings: "Zinc protects against UV radiation, enhances wound healing, contributes to immune and neuropsychiatric functions, and decreases the relative risk of cancer and cardiovascular disease." So, in addition to the antioxidant benefits zinc offers to our skin, zinc is also important for the proper functioning of the immune system
By Phylameana lila Desy
In this article we will explore various vitamins and minerals to learn how they affect the health of your skin and hopefully help you break-free from unsightly blemishes and break-out into a beautiful radiant smile.
From a holistic point of view all illnesses are manifestations of our imbalances. In treating acne outbreaks the holistic practitioner would typically consider all emotional, physical, mental, or even spiritual imbalances. Any treatments offered would address the whole person, not just the physical body.
For example, Louise Hay, author of The New York Times best seller self-help book You Can Heal Your Life, teaches that acne is a manifestation of not loving or accepting yourself. Hays suggests this affirmation for those with acne: I am a Divine expression of life, I love and accept myself where I am right now..
Some holistic practitioners also cite poor diets and deficiencies in vitamins and minerals as factors that upset the natural internal workings of physical organs and disturb optimal blood circulation. In Ayurvedic medicine, acne (known clinically as Yauvan Pidika) is believed to be an internal constitutional disorder of the body and is caused primarily by improper diet, impurities in the blood, and imbalances in Kapha and Vata. However, there is virtually no scientific evidence linking diet to acne, and dermatologists dismiss such claims."
Vitamin Treatments for Acne
Healthy and radiant skin requires proper nutrition. However, according to a 2007 report by the Center for Disease Control and Prevention, 39.5 percent of Americans eat less than the recommended three to five servings of fruits and vegetables each day. Deficiencies in vitamins and minerals can affect the body's ability to function optimally. Vitamins and minerals can be taken to supplement our diets when our nutritional needs are lacking through food consumption alone.
However, multivitamins should not be taken as a substitute for eating healthy foods. Taking too much of any vitamin or mineral can be toxic and extremely dangerous. Please consult with a doctor or other trained healthcare professional before taking any dietary supplements.
* Vitamin A - Retinoids, derivatives of vitamin A, are used to treat acne and other skin disorders. Retinoids are prescribed by dermatologists both topically and orally. A common type of retinoid used in the oral treatment of acne is isotretinoin.
* Omega-3 Fatty Acids - Omega-3 fatty acids from fish oil, chromium, zinc, and selenium are nutrients that may have both anti-acne and mood regulating properties according to an acne study conducted at the Lasky Skin Clinic in 2008.
* Zinc - The National Library of Science recognizes that zinc may be effective in the treatment of acne based on available science evidence. The Department of Dermatology at SUNY Downstate Medical Center in New York also recognizes zinc, along with vitamin A, and tea tree oil (also ayurvedic therapies) as over-the-counter remedies available for treating acne. However, its position on these remedies is that additional and better studies are needed to clarify the benefits.
Essential Vitamins for Skin Care in General
* Vitamin A - According to Dr. Eugene S. Bereston "the therapeutic use of Vitamin A began almost with the discovery of the vitamin." Bereston also noted that the first property of vitamin A is its ability to stimulate growth. The American Academy of Dermatology reports that vitamin A is vital to the health of both your skin and your eyes. The academy recommends a daily dose of vitamin A. Examples of vitamin A enriched foods include citrus fruits, carrots, tomatoes, yellow squash, and pumpkin. Vitamin A can also be applied to the skin topically with creams to promote cell growth.
* Vitamin B - The Office of Dietary Supplements at the National Institute of Health states that inflammation of the skin is one sign of B6 deficiency. Clinical signs of vitamin B6 deficiency are rarely seen in the United States. Alcoholics and aging adults are at the highest risk for B6 deficiencies due to poor dietary habits.
* Vitamins C and E - The American Academy of Dermatology recommends daily oral dosages of vitamins C and E to protect the body and for its antioxidant properties that are important for healthy skin.
* Zinc - A study conducted at Duke University provides evidence that Zinc is an important antioxidant supporting healthy skin. Among the findings: "Zinc protects against UV radiation, enhances wound healing, contributes to immune and neuropsychiatric functions, and decreases the relative risk of cancer and cardiovascular disease." So, in addition to the antioxidant benefits zinc offers to our skin, zinc is also important for the proper functioning of the immune system
By Phylameana lila Desy
Vitamin B12 - What You Need to Know
One of the eight B vitamins, vitamin B12 is a water-soluble nutrient that is vital to the body's overall wellbeing. It contains the element of cobalt and as a result one of the formal or scientific names for vitamin B12 is "cobalamin". Unlike many vitamins, B12 is not found in animals or plants. In fact, it is exclusively produced by bacteria. When animals consume plants or drink water contaminated by these specific bacteria, the vitamin ends up being stored in their body, mostly in the liver.
Vitamin B12 assists the body in more ways than one – although one of the key functions it performs is to help in the making of red blood cells. These cells help deliver oxygen to the body's vital organs, including the heart and brain. This oxygen is important in providing you with the necessary energy to get through each day. Vitamin B12 also assists in white blood cell production, which is crucial to keeping the immune system strong, which in turn keeps the body healthy.
Another way vitamin B12 benefits the body is by properly maintaining the nervous system and helping to keep nerve cells healthy, which keeps the brain functioning the way it should. The B12 vitamin also assists in the creation and regulation of DNA, which is present in every cell in the body. Since this nutrient is also a very powerful antioxidant, it helps fight off free radicals which researchers have said can lead to cancer.
Vitamin B12 is an important nutrient that everyone should have in their diet - it can be found in meat, fish, dairy, and eggs. If your lifestyle does not permit some of these B12 rich foods, it's important to take a supplement that will top up your daily requirement. By making sure you do have enough vitamin B12 in your body, you can avoid permanent nerve damage with associated symptoms like pins and needles, numbness, tingling, memory loss, attention deficit disorder, depression, dizziness, fatigue and mood swings.
Vitamin B12 assists the body in more ways than one – although one of the key functions it performs is to help in the making of red blood cells. These cells help deliver oxygen to the body's vital organs, including the heart and brain. This oxygen is important in providing you with the necessary energy to get through each day. Vitamin B12 also assists in white blood cell production, which is crucial to keeping the immune system strong, which in turn keeps the body healthy.
Another way vitamin B12 benefits the body is by properly maintaining the nervous system and helping to keep nerve cells healthy, which keeps the brain functioning the way it should. The B12 vitamin also assists in the creation and regulation of DNA, which is present in every cell in the body. Since this nutrient is also a very powerful antioxidant, it helps fight off free radicals which researchers have said can lead to cancer.
Vitamin B12 is an important nutrient that everyone should have in their diet - it can be found in meat, fish, dairy, and eggs. If your lifestyle does not permit some of these B12 rich foods, it's important to take a supplement that will top up your daily requirement. By making sure you do have enough vitamin B12 in your body, you can avoid permanent nerve damage with associated symptoms like pins and needles, numbness, tingling, memory loss, attention deficit disorder, depression, dizziness, fatigue and mood swings.
Does Vitamin E Help the Skin?
Vitamin E is a fat-soluble vitamin that boasts numerous benefits for the skin. There are a cluster of compounds within vitamin E, especially d-alpha-tocopherol; known for their antioxidant abilities. As an antioxidant, vitamin E works to shield skin cells from oxidation and prevent free radicals from causing cellular and tissue damage. Vitamin E is regularly found in skin care products since it promotes the maintenance and overall health of
Significance
1. Vitamin E plays a role in protecting skin cells from potentially dangerous elements that generate free radicals (molecules holding an unshared electron), by providing its own electron to the electron deficient free radical, to stabilize it. According to an article in the Skin Pharmacology and Physiology journal, "Oxidants and antioxidants play an important role in maintaining a balance between free radicals produced by metabolism or derived from environmental sources."
Effects
2. The Online-Vitamins-Guide notes, how by combating free radicals and oxidation, vitamin E helps reduce the development and appearance of age spots, stretch marks, lines, wrinkles, scar tissue and skin inflammation.
Features
3. According to altMD, vitamin E helps skin stay hydrated by preserving its oil balance, increasing the skin's barrier function. Moreover, when applied topically, vitamin E is used as a naturopathic remedy for skin burns, scars and reducing the symptoms and irritations of skin conditions, such as cold sores, eczema, erythema, hemorrhoids, psoriasis, shingles and skin ulcers.
Function
4. Additionally, vitamin E serves as a regulator for the vitamin A; a central vitamin for skin care, and works alongside the circulatory system to support blood clotting and the skin's ability to heal, according to Online-Vitamins-Guide.
Considerations
5. The effectiveness of vitamin E is still being researched. The Mayo Clinic asserts that "Aside from the treatment of vitamin E deficiency (which is rare), there are no clearly proven medicinal uses of vitamin E supplementation beyond the recommended daily allowance."
by: Serena Spinello
Significance
1. Vitamin E plays a role in protecting skin cells from potentially dangerous elements that generate free radicals (molecules holding an unshared electron), by providing its own electron to the electron deficient free radical, to stabilize it. According to an article in the Skin Pharmacology and Physiology journal, "Oxidants and antioxidants play an important role in maintaining a balance between free radicals produced by metabolism or derived from environmental sources."
Effects
2. The Online-Vitamins-Guide notes, how by combating free radicals and oxidation, vitamin E helps reduce the development and appearance of age spots, stretch marks, lines, wrinkles, scar tissue and skin inflammation.
Features
3. According to altMD, vitamin E helps skin stay hydrated by preserving its oil balance, increasing the skin's barrier function. Moreover, when applied topically, vitamin E is used as a naturopathic remedy for skin burns, scars and reducing the symptoms and irritations of skin conditions, such as cold sores, eczema, erythema, hemorrhoids, psoriasis, shingles and skin ulcers.
Function
4. Additionally, vitamin E serves as a regulator for the vitamin A; a central vitamin for skin care, and works alongside the circulatory system to support blood clotting and the skin's ability to heal, according to Online-Vitamins-Guide.
Considerations
5. The effectiveness of vitamin E is still being researched. The Mayo Clinic asserts that "Aside from the treatment of vitamin E deficiency (which is rare), there are no clearly proven medicinal uses of vitamin E supplementation beyond the recommended daily allowance."
by: Serena Spinello
Vitamin E: A Valuable Antioxidant
Vitamin E: A Valuable Antioxidant
Other Key Nutrients for the Mom-to-Be
-- By BabyFit
Vitamin E acts as an antioxidant that prevents premature reaction to oxygen in the body and the breakdown of many substances in the body. It neutralizes free radicals that could cause damage to cells and tissue, while aiding in circulation, clotting, and healing. Some studies have even shown that vitamin E decreases symptoms of premenstrual syndrome and certain types of breast cancer. Other studies have shown that taking large doses of vitamin E has decreased the risk of Coronary Artery Disease.
Most vegetable oils, wheat germ, soybean oil, safflower oil, raw seeds and nuts, egg yolk, whole grain products, beef liver, peanut butter, and unrefined cereal products are good sources of vitamin E.
Women need 15 mg of vitamin E on a daily basis. Pregnant and nursing moms should consume 15 mg and 19 mg daily, respectively. Though it is almost impossible to have a vitamin E deficiency, too much can cause nausea and digestive tract problems. Prolonged overexposure can lead to toxicity and other health problems.
Food Source Milligrams (%RDA)
Wheat Germ Oil, 1 tablespoon 20.3 (135%)
Almonds, 1 ounce 7.4 (49%)
Safflower Oil, 1 tablespoon 4.6 (31%)
Peanuts, 1 ounce 2.2 (15%)
Spinach, 1/2 cup cooked 1.6 (11%)
Soybean Oil, 1 tablespoon 1.3 (9%)
Turnip Greens, 1 cup cooked 1.3 (9%)
Broccoli, 1/2 cup cooked 1.2 (8%)
Corn Oil, 1 Tablespoon 1.2 (8%)
Kiwi, 1 fruit 1.1 (7%)
Mango, 1 fruit 0.9 (6%)
Other Key Nutrients for the Mom-to-Be
-- By BabyFit
Vitamin E acts as an antioxidant that prevents premature reaction to oxygen in the body and the breakdown of many substances in the body. It neutralizes free radicals that could cause damage to cells and tissue, while aiding in circulation, clotting, and healing. Some studies have even shown that vitamin E decreases symptoms of premenstrual syndrome and certain types of breast cancer. Other studies have shown that taking large doses of vitamin E has decreased the risk of Coronary Artery Disease.
Most vegetable oils, wheat germ, soybean oil, safflower oil, raw seeds and nuts, egg yolk, whole grain products, beef liver, peanut butter, and unrefined cereal products are good sources of vitamin E.
Women need 15 mg of vitamin E on a daily basis. Pregnant and nursing moms should consume 15 mg and 19 mg daily, respectively. Though it is almost impossible to have a vitamin E deficiency, too much can cause nausea and digestive tract problems. Prolonged overexposure can lead to toxicity and other health problems.
Food Source Milligrams (%RDA)
Wheat Germ Oil, 1 tablespoon 20.3 (135%)
Almonds, 1 ounce 7.4 (49%)
Safflower Oil, 1 tablespoon 4.6 (31%)
Peanuts, 1 ounce 2.2 (15%)
Spinach, 1/2 cup cooked 1.6 (11%)
Soybean Oil, 1 tablespoon 1.3 (9%)
Turnip Greens, 1 cup cooked 1.3 (9%)
Broccoli, 1/2 cup cooked 1.2 (8%)
Corn Oil, 1 Tablespoon 1.2 (8%)
Kiwi, 1 fruit 1.1 (7%)
Mango, 1 fruit 0.9 (6%)
Vitamin E and Cancer-free
Vitamin E is of tremendous dietary importance because it functions as an antioxidant. It goes around the body scavenging free radicals of oxygen and detoxifying them. This is a critical activity in the brain, as it is the body's largest consumer of oxygen and throws off free radicals in the course of the fast and furious metabolic activity that powers every thought, feeling, memory and action you take (and even the ones you only think about) and every dream you dream.
The gradual accumulation of damage from free radicals over the years is thought to be a factor causing the decline in mental faculties often -- but not always -- seen with age. Free radical damage is also now implicated as a cause of Alzheimer's disease. It is widely suspected of being a major contributor to heart disease and cancer as well. What is more, cataracts are thought to result from free radical damage to the eyes. And much of the destructive effect of diabetes is attributed to free radicals.
Although surely the last word on Vitamin E has not been written, a number of studies suggest that the vitamin is essential to mental health particularly as people age.
In one study, reported in the Journal of Nutrition, researchers looked at the vitamin E status of 120 elderly people who were particularly healthy. They also looked at the cognitive performance of the men and women by administering a highly reliable questionnaire assessing intellectual function, and counted the errors the respondents made.
Persons with the lowest levels of Vitamin D made the greatest number of errors. And those who made no errors at all had significantly higher blood levels of Vitamin E than those who made errors. The authors conclude that Vitamin E is essential to cognitive function, and that the vitamin is especially important for those over 65. Or anyone who wants to maintain mental facility, as the vitamin appears to slow mental decline.
Of course, no single food supplies all the nutrients you need for a healthy diet. Vitamin E is a fat-soluble vitamin found in vegetable oils, nuts and green leafy vegetables. It is also found in grains, particularly in whole grains.
The Recommended Dietary Allowance for Vitamin E for adults is 15 mg, or 22 International Units. According to recent surveys of the U.S. Department of Agriculture, the intake of Vitamin E by women between the ages of 19 and 50 averaged less than 90% of the RDA. Men appear to be getting close to 100% of the RDA. However, many researchers believe that the current RDA for Vitamin E is not sufficient to fully protect the body.
The way you store and prepare foods dramatically influences the nutrients they retain and that you actually consume. As with all nutrients, Vitamin E can be lost with exposure to light. It's best to store foods in airtight containers.
By Hara Estroff Marano, published on October 02, 2002 - last reviewed on December 05, 2005
The gradual accumulation of damage from free radicals over the years is thought to be a factor causing the decline in mental faculties often -- but not always -- seen with age. Free radical damage is also now implicated as a cause of Alzheimer's disease. It is widely suspected of being a major contributor to heart disease and cancer as well. What is more, cataracts are thought to result from free radical damage to the eyes. And much of the destructive effect of diabetes is attributed to free radicals.
Although surely the last word on Vitamin E has not been written, a number of studies suggest that the vitamin is essential to mental health particularly as people age.
In one study, reported in the Journal of Nutrition, researchers looked at the vitamin E status of 120 elderly people who were particularly healthy. They also looked at the cognitive performance of the men and women by administering a highly reliable questionnaire assessing intellectual function, and counted the errors the respondents made.
Persons with the lowest levels of Vitamin D made the greatest number of errors. And those who made no errors at all had significantly higher blood levels of Vitamin E than those who made errors. The authors conclude that Vitamin E is essential to cognitive function, and that the vitamin is especially important for those over 65. Or anyone who wants to maintain mental facility, as the vitamin appears to slow mental decline.
Of course, no single food supplies all the nutrients you need for a healthy diet. Vitamin E is a fat-soluble vitamin found in vegetable oils, nuts and green leafy vegetables. It is also found in grains, particularly in whole grains.
The Recommended Dietary Allowance for Vitamin E for adults is 15 mg, or 22 International Units. According to recent surveys of the U.S. Department of Agriculture, the intake of Vitamin E by women between the ages of 19 and 50 averaged less than 90% of the RDA. Men appear to be getting close to 100% of the RDA. However, many researchers believe that the current RDA for Vitamin E is not sufficient to fully protect the body.
The way you store and prepare foods dramatically influences the nutrients they retain and that you actually consume. As with all nutrients, Vitamin E can be lost with exposure to light. It's best to store foods in airtight containers.
By Hara Estroff Marano, published on October 02, 2002 - last reviewed on December 05, 2005
11/7/09
Vitamin
A vitamin is an organic compound required as a nutrient in tiny amounts by an organism.[1] The term 'vitamin' first became popular in the early 1800's as a contraction of the words 'vital' and 'mineral', though the actual meaning of the word has developed somewhat since that time[2]. A compound is called a vitamin when it cannot be synthesized in sufficient quantities by an organism, and must be obtained from the diet. Thus, the term is conditional both on the circumstances and the particular organism. For example, ascorbic acid functions as vitamin C for some animals but not others, and vitamins D and K are required in the human diet only in certain circumstances.[3] The term vitamin does not include other essential nutrients such as dietary minerals, essential fatty acids, or essential amino acids, nor does it encompass the large number of other nutrients that promote health but are otherwise required less often.[4]
Vitamins are classified by their biological and chemical activity, not their structure. Thus, each "vitamin" may refer to several vitamer compounds that all show the biological activity associated with a particular vitamin. Such a set of chemicals are grouped under an alphabetized vitamin "generic descriptor" title, such as "vitamin A", which includes the compounds retinal, retinol, and many carotenoids.[5] Vitamers are often inter-converted in the body.
Vitamins have diverse biochemical functions, including function as hormones (e.g. vitamin D), antioxidants (e.g. vitamin E), and mediators of cell signaling and regulators of cell and tissue growth and differentiation (e.g. vitamin A).[6] The largest number of vitamins (e.g. B complex vitamins) function as precursors for enzyme cofactor bio-molecules (coenzymes), that help act as catalysts and substrates in metabolism. When acting as part of a catalyst, vitamins are bound to enzymes and are called prosthetic groups. For example, biotin is part of enzymes involved in making fatty acids. Vitamins also act as coenzymes to carry chemical groups between enzymes. For example, folic acid carries various forms of carbon group – methyl, formyl and methylene - in the cell. Although these roles in assisting enzyme reactions are vitamins' best-known function, the other vitamin functions are equally important.[7]
Until the 1900s, vitamins were obtained solely through food intake, and changes in diet (which, for example, could occur during a particular growing season) can alter the types and amounts of vitamins ingested. Vitamins have been produced as commodity chemicals and made widely available as inexpensive pills for several decades,[8] allowing supplementation of the dietary intake.
Contents
[hide]
* 1 History
* 2 In humans
o 2.1 List of vitamins
* 3 In nutrition and diseases
o 3.1 Deficiencies
o 3.2 Side effects and overdose
* 4 Supplements
o 4.1 Governmental regulation of vitamin supplements
* 5 Names in current and previous nomenclatures
* 6 See also
* 7 References
* 8 External links
[edit] History
The discovery of vitamins and their sources Year of discovery Vitamin Source
1909 Vitamin A (Retinol) Cod liver oil
1912 Vitamin B1 (Thiamine) Rice bran
1912 Vitamin C (Ascorbic acid) Lemons
1918 Vitamin D (Calciferol) Cod liver oil
1920 Vitamin B2 (Riboflavin) Eggs
1922 Vitamin E (Tocopherol) Wheat germ oil,
Cosmetics and Liver
1926 Vitamin B12 (Cyanocobalamin) Liver
1929 Vitamin K (Phylloquinone) Alfalfa
1931 Vitamin B5 (Pantothenic acid) Liver
1931 Vitamin B7 (Biotin) Liver
1934 Vitamin B6 (Pyridoxine) Rice bran
1936 Vitamin B3 (Niacin) Liver
1941 Vitamin B9 (Folic acid) Liver
The value of eating a certain food to maintain health was recognized long before vitamins were identified. The ancient Egyptians knew that feeding liver to a patient would help cure night blindness, an illness now known to be caused by a vitamin A deficiency.[9] The advancement of ocean voyage during the Renaissance resulted in prolonged periods without access to fresh fruits and vegetables, and made illnesses from vitamin deficiency common among ships' crews.[10]
In 1749, the Scottish surgeon James Lind discovered that citrus foods helped prevent scurvy, a particularly deadly disease in which collagen is not properly formed, causing poor wound healing, bleeding of the gums, severe pain, and death.[9] In 1753, Lind published his Treatise on the Scurvy, which recommended using lemons and limes to avoid scurvy, which was adopted by the British Royal Navy. This led to the nickname Limey for sailors of that organization. Lind's discovery, however, was not widely accepted by individuals in the Royal Navy's Arctic expeditions in the 19th century, where it was widely believed that scurvy could be prevented by practicing good hygiene, regular exercise, and by maintaining the morale of the crew while on board, rather than by a diet of fresh food.[9] As a result, Arctic expeditions continued to be plagued by scurvy and other deficiency diseases. In the early 20th century, when Robert Falcon Scott made his two expeditions to the Antarctic, the prevailing medical theory was that scurvy was caused by "tainted" canned food.[9]
During the late 18th and early 19th centuries, the use of deprivation studies allowed scientists to isolate and identify a number of vitamins. Initially, lipid from fish oil was used to cure rickets in rats, and the fat-soluble nutrient was called "antirachitic A". Thus, the first "vitamin" bioactivity ever isolated, which cured rickets, was initially called "vitamin A", although confusingly the bioactivity of this compound is now called vitamin D.[11] In 1881, Russian surgeon Nikolai Lunin studied the effects of scurvy while at the University of Tartu in present-day Estonia.[12] He fed mice an artificial mixture of all the separate constituents of milk known at that time, namely the proteins, fats, carbohydrates, and salts. The mice that received only the individual constituents died, while the mice fed by milk itself developed normally. He made a conclusion that "a natural food such as milk must therefore contain, besides these known principal ingredients, small quantities of unknown substances essential to life."[12] However, his conclusions were rejected by other researchers when they were unable to reproduce his results. One difference was that he had used table sugar (sucrose), while other researchers had used milk sugar (lactose) that still contained small amounts of vitamin B.
Image illustrating rich and good nutritional sources of copper including: oysters, beef or lamb liver, Brazil nuts, blackstrap molasses, cocoa, and black pepper, lobster, nuts and sunflower seeds, green olives, and wheat bran.
The Ancient Egyptians knew that feeding a patient liver (back, right) would help cure night blindness.
In east Asia, where polished white rice was the common staple food of the middle class, beriberi resulting from lack of vitamin B1 was endemic. In 1884, Takaki Kanehiro, a British trained medical doctor of the Imperial Japanese Navy, observed that beriberi was endemic among low-ranking crew who often ate nothing but rice, but not among crews of Western navies and officers who consumed a Western-style diet. With the support of the Japanese navy, he experimented using crews of two battleships; one crew was fed only white rice, while the other was fed a diet of meat, fish, barley, rice, and beans. The group that ate only white rice documented 161 crew members with beriberi and 25 deaths, while the latter group had only 14 cases of beriberi and no deaths. This convinced Kanehiro and the Japanese Navy that diet was the cause of beriberi, but mistakenly believed that sufficient amounts of protein prevented it.[13] That diseases could result from some dietary deficiencies was further investigated by Christiaan Eijkman, who in 1897 discovered that feeding unpolished rice instead of the polished variety to chickens helped to prevent beriberi in the chickens. The following year, Frederick Hopkins postulated that some foods contained "accessory factors"—in addition to proteins, carbohydrates, fats, et cetera—that were necessary for the functions of the human body.[9] Hopkins and Eijkman were awarded the Nobel Prize for Physiology or Medicine in 1929 for their discovery of several vitamins.[14]
In 1910, Japanese scientist Umetaro Suzuki succeeded in extracting a water-soluble complex of micronutrients from rice bran and named it aberic acid. He published this discovery in a Japanese scientific journal.[15] When the article was translated into German, the translation failed to state that it was a newly discovered nutrient, a claim made in the original Japanese article, and hence his discovery failed to gain publicity. In 1912 Polish biochemist Kazimierz Funk isolated the same complex of micronutrients and proposed the complex be named "Vitamine" (a portmanteau of "vital amine").[16] The name soon became synonymous with Hopkins' "accessory factors", and by the time it was shown that not all vitamins were amines, the word was already ubiquitous. In 1920, Jack Cecil Drummond proposed that the final "e" be dropped to deemphasize the "amine" reference after the discovery that vitamin C had no amine component.[13]
In 1931, Albert Szent-Györgyi and a fellow researcher Joseph Svirbely determined that "hexuronic acid" was actually vitamin C and noted its anti-scorbutic activity. In 1937, Szent-Györgyi was awarded the Nobel Prize in Physiology or Medicine for his discovery. In 1943 Edward Adelbert Doisy and Henrik Dam were awarded the Nobel Prize in Physiology or Medicine for their discovery of vitamin K and its chemical structure. In 1967, George Wald was awarded the Nobel Prize (along with Ragnar Granit and Haldan Keffer Hartline) for his discovery that vitamin A could participate directly in a physiological process.[14]
[edit] In humans
Vitamins are classified as either water-soluble or fat soluble. In humans there are 13 vitamins: 4 fat-soluble (A, D, E and K) and 9 water-soluble (8 B vitamins and vitamin C). Water-soluble vitamins dissolve easily in water, and in general, are readily excreted from the body, to the degree that urinary output is a strong predictor of vitamin consumption.[17] Because they are not readily stored, consistent daily intake is important.[18] Many types of water-soluble vitamins are synthesized by bacteria.[19] Fat-soluble vitamins are absorbed through the intestinal tract with the help of lipids (fats). Because they are more likely to accumulate in the body, they are more likely to lead to hypervitaminosis than are water-soluble vitamins. Fat-soluble vitamin regulation is of particular significance in cystic fibrosis.[20]
[edit] List of vitamins
Each vitamin is typically used in multiple reactions and, therefore, most have multiple functions.[21]
Vitamin generic
descriptor name ↓ Vitamer chemical name(s) (list not complete) ↓ Solubility ↓ Recommended dietary allowances
(male, age 19–70)[22] Deficiency disease Upper Intake Level
(UL/day)[22] Overdose disease
Vitamin A Retinoids
(retinol, retinoids
and carotenoids) Fat 900 µg Night-blindness and
Keratomalacia[23] 3,000 µg Hypervitaminosis A
Vitamin B1 Thiamine Water 1.2 mg Beriberi, Wernicke-Korsakoff syndrome N/D[24] Drowsiness or muscle relaxation with large doses.[25]
Vitamin B2 Riboflavin Water 1.3 mg Ariboflavinosis N/D
Vitamin B3 Niacin, niacinamide Water 16.0 mg Pellagra 35.0 mg Liver damage (doses > 2g/day)[26] and other problems
Vitamin B5 Pantothenic acid Water 5.0 mg[27] Paresthesia N/D Diarrhea; possibly nausea and heartburn.[28]
Vitamin B6 Pyridoxine, pyridoxamine, pyridoxal Water 1.3–1.7 mg Anemia[29] peripheral neuropathy. 100 mg Impairment of proprioception, nerve damage (doses > 100 mg/day)
Vitamin B7 Biotin Water 30.0 µg Dermatitis, enteritis N/D
Vitamin B9 Folic acid, folinic acid Water 400 µg Deficiency during pregnancy is associated with birth defects, such as neural tube defects 1,000 µg May mask symptoms of vitamin B12 deficiency; other effects.
Vitamin B12 Cyanocobalamin, hydroxycobalamin, methylcobalamin Water 2.4 µg Megaloblastic anemia[30] N/D No known toxicity[30]
Vitamin C Ascorbic acid Water 90.0 mg Scurvy 2,000 mg Vitamin C megadosage
Vitamin D Ergocalciferol, cholecalciferol Fat 5.0 µg–10 µg[31] Rickets and Osteomalacia 50 µg Hypervitaminosis D
Vitamin E Tocopherols, tocotrienols Fat 15.0 mg Deficiency is very rare; mild hemolytic anemia in newborn infants.[32] 1,000 mg Increased congestive heart failure seen in one large randomized study.[33]
Vitamin K phylloquinone, menaquinones Fat 120 µg Bleeding diathesis N/D Increases coagulation in patients taking warfarin.[34]
[edit] In nutrition and diseases
Vitamins are essential for the normal growth and development of a multicellular organism. Using the genetic blueprint inherited from its parents, a fetus begins to develop, at the moment of conception, from the nutrients it absorbs. It requires certain vitamins and minerals to be present at certain times. These nutrients facilitate the chemical reactions that produce among other things, skin, bone, and muscle. If there is serious deficiency in one or more of these nutrients, a child may develop a deficiency disease. Even minor deficiencies may cause permanent damage.[35]
For the most part, vitamins are obtained with food, but a few are obtained by other means. For example, microorganisms in the intestine—commonly known as "gut flora"—produce vitamin K and biotin, while one form of vitamin D is synthesized in the skin with the help of the natural ultraviolet wavelength of sunlight. Humans can produce some vitamins from precursors they consume. Examples include vitamin A, produced from beta carotene, and niacin, from the amino acid tryptophan.[22]
Once growth and development are completed, vitamins remain essential nutrients for the healthy maintenance of the cells, tissues, and organs that make up a multicellular organism; they also enable a multicellular life form to efficiently use chemical energy provided by food it eats, and to help process the proteins, carbohydrates, and fats required for respiration.[6]
[edit] Deficiencies
Because human bodies do not store most vitamins, humans must consume them regularly to avoid deficiency. Human bodily stores for different vitamins vary widely; vitamins A, D, and B12 are stored in significant amounts in the human body, mainly in the liver,[32] and an adult human's diet may be deficient in vitamins A and B12 for many months before developing a deficiency condition. Vitamin B3 is not stored in the human body in significant amounts, so stores may only last a couple of weeks.[23][32] Deficiencies of vitamins are classified as either primary or secondary. A primary deficiency occurs when an organism does not get enough of the vitamin in its food. A secondary deficiency may be due to an underlying disorder that prevents or limits the absorption or use of the vitamin, due to a “lifestyle factor”, such as smoking, excessive alcohol consumption, or the use of medications that interfere with the absorption or use of the vitamin.[32] People who eat a varied diet are unlikely to develop a severe primary vitamin deficiency. In contrast, restrictive diets have the potential to cause prolonged vitamin deficits, which may result in often painful and potentially deadly diseases.
Well-known human vitamin deficiencies involve thiamine (beriberi), niacin (pellagra), vitamin C (scurvy) and vitamin D (rickets). In much of the developed world, such deficiencies are rare; this is due to (1) an adequate supply of food; and (2) the addition of vitamins and minerals to common foods, often called fortification.[22][32] In addition to these classical vitamin deficiency diseases, some evidence has also suggested links between vitamin deficiency and a number of different disorders.[36][37]
[edit] Side effects and overdose
In large doses, some vitamins have documented side effects that tend to be more severe with a larger dosage. The likelihood of consuming too much of any vitamin from food is remote, but overdosing from vitamin supplementation does occur. At high enough dosages some vitamins cause side effects such as nausea, diarrhea, and vomiting.[23][38]
When side effects emerge, recovery is often accomplished by reducing the dosage. The concentrations of vitamins an individual can tolerate vary widely, and appear to be related to age and state of health.[39] In the United States, overdose exposure to all formulations of vitamins was reported by 62,562 individuals in 2004 (nearly 80% of these exposures were in children under the age of 6), leading to 53 "major" life-threatening outcomes and 3 deaths[40];a small number in comparison to the 19,250 people who died of unintentional poisoning of all kinds in the U.S. in the same year (2004).[41]
[edit] Supplements
Dietary supplements, often containing vitamins, are used to ensure that adequate amounts of nutrients are obtained on a daily basis, if optimal amounts of the nutrients cannot be obtained through a varied diet. Scientific evidence supporting the benefits of some vitamin supplements is well established for certain health conditions, but others need further study.[42] In some cases, vitamin supplements may have unwanted effects, especially if taken before surgery, with other dietary supplements or medicines, or if the person taking them has certain health conditions.[42] Dietary supplements may also contain levels of vitamins many times higher, and in different forms, than one may ingest through food.[43]
A meta-analysis published in 2006 suggested that Vitamin A and E supplements not only provide no tangible health benefits for generally healthy individuals, but may actually increase mortality, although two large studies included in the analysis involved smokers, for which it was already known that beta-carotene supplements can be harmful.[44] Another study released in May 2009 found that antioxidants such as vitamins C and E may actually curb some benefits of exercise.[45]
[edit] Governmental regulation of vitamin supplements
Most countries place dietary supplements in a special category under the general umbrella of foods, not drugs. This necessitates that the manufacturer, and not the government, be responsible for ensuring that its dietary supplement products are safe before they are marketed. Unlike drug products, which must explicitly be proven safe and effective for their intended use before marketing, there are often no provisions to "approve" dietary supplements for safety or effectiveness before they reach the consumer. Also unlike drug products, manufacturers and distributors of dietary supplements are not generally required to report any claims of injuries or illnesses that may be related to the use of their products.[46][47][42]
[edit] Names in current and previous nomenclatures
Nomenclature of reclassified vitamins Previous name Chemical name Reason for name change[48]
Vitamin B4 Adenine DNA metabolite
Vitamin B8 Adenylic acid DNA metabolite
Vitamin F Essential fatty acids Needed in large quantities (does
not fit the definition of a vitamin).
Vitamin G Riboflavin Reclassified as Vitamin B2
Vitamin H Biotin Reclassified as Vitamin B7
Vitamin J Catechol, Flavin Protein metabolite
Vitamin L1[49] Anthranilic acid Protein metabolite
Vitamin L2[49] Adenylthiomethylpentose RNA metabolite
Vitamin M Folic acid Reclassified as Vitamin B9
Vitamin O Carnitine Protein metabolite
Vitamin P Flavonoids No longer classified as a vitamin
Vitamin PP Niacin Reclassified as Vitamin B3
Vitamin U S-Methylmethionine Protein metabolite
The reason the set of vitamins seems to skip directly from E to K is that the vitamins corresponding to "letters" F-J were either reclassified over time, discarded as false leads, or renamed because of their relationship to "vitamin B", which became a "complex" of vitamins. The German-speaking scientists who isolated and described vitamin K (in addition to naming it as such) did so because the vitamin is intimately involved in the Koagulation of blood following wounding. At the time, most (but not all) of the letters from F through to J were already designated, so the use of the letter K was considered quite reasonable.[48][50] The table on the right lists chemicals that had previously been classified as vitamins, as well as the earlier names of vitamins that later became part of the B-complex.
[edit] See also
* Antioxidant
* Dietary supplement
* Dietetics
* Health freedom movement
* Illnesses related to poor nutrition
* Megavitamin therapy
* Nutrition
o Vitamin deficiency
o Dietary minerals
o Essential amino acids
o Essential nutrients
o Nootropics
o Nutrients
* Orthomolecular medicine
* Pharmacology
* Vitamin poisoning (overdose)
* Whole food supplements
source: wikipedia.org
Vitamins are classified by their biological and chemical activity, not their structure. Thus, each "vitamin" may refer to several vitamer compounds that all show the biological activity associated with a particular vitamin. Such a set of chemicals are grouped under an alphabetized vitamin "generic descriptor" title, such as "vitamin A", which includes the compounds retinal, retinol, and many carotenoids.[5] Vitamers are often inter-converted in the body.
Vitamins have diverse biochemical functions, including function as hormones (e.g. vitamin D), antioxidants (e.g. vitamin E), and mediators of cell signaling and regulators of cell and tissue growth and differentiation (e.g. vitamin A).[6] The largest number of vitamins (e.g. B complex vitamins) function as precursors for enzyme cofactor bio-molecules (coenzymes), that help act as catalysts and substrates in metabolism. When acting as part of a catalyst, vitamins are bound to enzymes and are called prosthetic groups. For example, biotin is part of enzymes involved in making fatty acids. Vitamins also act as coenzymes to carry chemical groups between enzymes. For example, folic acid carries various forms of carbon group – methyl, formyl and methylene - in the cell. Although these roles in assisting enzyme reactions are vitamins' best-known function, the other vitamin functions are equally important.[7]
Until the 1900s, vitamins were obtained solely through food intake, and changes in diet (which, for example, could occur during a particular growing season) can alter the types and amounts of vitamins ingested. Vitamins have been produced as commodity chemicals and made widely available as inexpensive pills for several decades,[8] allowing supplementation of the dietary intake.
Contents
[hide]
* 1 History
* 2 In humans
o 2.1 List of vitamins
* 3 In nutrition and diseases
o 3.1 Deficiencies
o 3.2 Side effects and overdose
* 4 Supplements
o 4.1 Governmental regulation of vitamin supplements
* 5 Names in current and previous nomenclatures
* 6 See also
* 7 References
* 8 External links
[edit] History
The discovery of vitamins and their sources Year of discovery Vitamin Source
1909 Vitamin A (Retinol) Cod liver oil
1912 Vitamin B1 (Thiamine) Rice bran
1912 Vitamin C (Ascorbic acid) Lemons
1918 Vitamin D (Calciferol) Cod liver oil
1920 Vitamin B2 (Riboflavin) Eggs
1922 Vitamin E (Tocopherol) Wheat germ oil,
Cosmetics and Liver
1926 Vitamin B12 (Cyanocobalamin) Liver
1929 Vitamin K (Phylloquinone) Alfalfa
1931 Vitamin B5 (Pantothenic acid) Liver
1931 Vitamin B7 (Biotin) Liver
1934 Vitamin B6 (Pyridoxine) Rice bran
1936 Vitamin B3 (Niacin) Liver
1941 Vitamin B9 (Folic acid) Liver
The value of eating a certain food to maintain health was recognized long before vitamins were identified. The ancient Egyptians knew that feeding liver to a patient would help cure night blindness, an illness now known to be caused by a vitamin A deficiency.[9] The advancement of ocean voyage during the Renaissance resulted in prolonged periods without access to fresh fruits and vegetables, and made illnesses from vitamin deficiency common among ships' crews.[10]
In 1749, the Scottish surgeon James Lind discovered that citrus foods helped prevent scurvy, a particularly deadly disease in which collagen is not properly formed, causing poor wound healing, bleeding of the gums, severe pain, and death.[9] In 1753, Lind published his Treatise on the Scurvy, which recommended using lemons and limes to avoid scurvy, which was adopted by the British Royal Navy. This led to the nickname Limey for sailors of that organization. Lind's discovery, however, was not widely accepted by individuals in the Royal Navy's Arctic expeditions in the 19th century, where it was widely believed that scurvy could be prevented by practicing good hygiene, regular exercise, and by maintaining the morale of the crew while on board, rather than by a diet of fresh food.[9] As a result, Arctic expeditions continued to be plagued by scurvy and other deficiency diseases. In the early 20th century, when Robert Falcon Scott made his two expeditions to the Antarctic, the prevailing medical theory was that scurvy was caused by "tainted" canned food.[9]
During the late 18th and early 19th centuries, the use of deprivation studies allowed scientists to isolate and identify a number of vitamins. Initially, lipid from fish oil was used to cure rickets in rats, and the fat-soluble nutrient was called "antirachitic A". Thus, the first "vitamin" bioactivity ever isolated, which cured rickets, was initially called "vitamin A", although confusingly the bioactivity of this compound is now called vitamin D.[11] In 1881, Russian surgeon Nikolai Lunin studied the effects of scurvy while at the University of Tartu in present-day Estonia.[12] He fed mice an artificial mixture of all the separate constituents of milk known at that time, namely the proteins, fats, carbohydrates, and salts. The mice that received only the individual constituents died, while the mice fed by milk itself developed normally. He made a conclusion that "a natural food such as milk must therefore contain, besides these known principal ingredients, small quantities of unknown substances essential to life."[12] However, his conclusions were rejected by other researchers when they were unable to reproduce his results. One difference was that he had used table sugar (sucrose), while other researchers had used milk sugar (lactose) that still contained small amounts of vitamin B.
Image illustrating rich and good nutritional sources of copper including: oysters, beef or lamb liver, Brazil nuts, blackstrap molasses, cocoa, and black pepper, lobster, nuts and sunflower seeds, green olives, and wheat bran.
The Ancient Egyptians knew that feeding a patient liver (back, right) would help cure night blindness.
In east Asia, where polished white rice was the common staple food of the middle class, beriberi resulting from lack of vitamin B1 was endemic. In 1884, Takaki Kanehiro, a British trained medical doctor of the Imperial Japanese Navy, observed that beriberi was endemic among low-ranking crew who often ate nothing but rice, but not among crews of Western navies and officers who consumed a Western-style diet. With the support of the Japanese navy, he experimented using crews of two battleships; one crew was fed only white rice, while the other was fed a diet of meat, fish, barley, rice, and beans. The group that ate only white rice documented 161 crew members with beriberi and 25 deaths, while the latter group had only 14 cases of beriberi and no deaths. This convinced Kanehiro and the Japanese Navy that diet was the cause of beriberi, but mistakenly believed that sufficient amounts of protein prevented it.[13] That diseases could result from some dietary deficiencies was further investigated by Christiaan Eijkman, who in 1897 discovered that feeding unpolished rice instead of the polished variety to chickens helped to prevent beriberi in the chickens. The following year, Frederick Hopkins postulated that some foods contained "accessory factors"—in addition to proteins, carbohydrates, fats, et cetera—that were necessary for the functions of the human body.[9] Hopkins and Eijkman were awarded the Nobel Prize for Physiology or Medicine in 1929 for their discovery of several vitamins.[14]
In 1910, Japanese scientist Umetaro Suzuki succeeded in extracting a water-soluble complex of micronutrients from rice bran and named it aberic acid. He published this discovery in a Japanese scientific journal.[15] When the article was translated into German, the translation failed to state that it was a newly discovered nutrient, a claim made in the original Japanese article, and hence his discovery failed to gain publicity. In 1912 Polish biochemist Kazimierz Funk isolated the same complex of micronutrients and proposed the complex be named "Vitamine" (a portmanteau of "vital amine").[16] The name soon became synonymous with Hopkins' "accessory factors", and by the time it was shown that not all vitamins were amines, the word was already ubiquitous. In 1920, Jack Cecil Drummond proposed that the final "e" be dropped to deemphasize the "amine" reference after the discovery that vitamin C had no amine component.[13]
In 1931, Albert Szent-Györgyi and a fellow researcher Joseph Svirbely determined that "hexuronic acid" was actually vitamin C and noted its anti-scorbutic activity. In 1937, Szent-Györgyi was awarded the Nobel Prize in Physiology or Medicine for his discovery. In 1943 Edward Adelbert Doisy and Henrik Dam were awarded the Nobel Prize in Physiology or Medicine for their discovery of vitamin K and its chemical structure. In 1967, George Wald was awarded the Nobel Prize (along with Ragnar Granit and Haldan Keffer Hartline) for his discovery that vitamin A could participate directly in a physiological process.[14]
[edit] In humans
Vitamins are classified as either water-soluble or fat soluble. In humans there are 13 vitamins: 4 fat-soluble (A, D, E and K) and 9 water-soluble (8 B vitamins and vitamin C). Water-soluble vitamins dissolve easily in water, and in general, are readily excreted from the body, to the degree that urinary output is a strong predictor of vitamin consumption.[17] Because they are not readily stored, consistent daily intake is important.[18] Many types of water-soluble vitamins are synthesized by bacteria.[19] Fat-soluble vitamins are absorbed through the intestinal tract with the help of lipids (fats). Because they are more likely to accumulate in the body, they are more likely to lead to hypervitaminosis than are water-soluble vitamins. Fat-soluble vitamin regulation is of particular significance in cystic fibrosis.[20]
[edit] List of vitamins
Each vitamin is typically used in multiple reactions and, therefore, most have multiple functions.[21]
Vitamin generic
descriptor name ↓ Vitamer chemical name(s) (list not complete) ↓ Solubility ↓ Recommended dietary allowances
(male, age 19–70)[22] Deficiency disease Upper Intake Level
(UL/day)[22] Overdose disease
Vitamin A Retinoids
(retinol, retinoids
and carotenoids) Fat 900 µg Night-blindness and
Keratomalacia[23] 3,000 µg Hypervitaminosis A
Vitamin B1 Thiamine Water 1.2 mg Beriberi, Wernicke-Korsakoff syndrome N/D[24] Drowsiness or muscle relaxation with large doses.[25]
Vitamin B2 Riboflavin Water 1.3 mg Ariboflavinosis N/D
Vitamin B3 Niacin, niacinamide Water 16.0 mg Pellagra 35.0 mg Liver damage (doses > 2g/day)[26] and other problems
Vitamin B5 Pantothenic acid Water 5.0 mg[27] Paresthesia N/D Diarrhea; possibly nausea and heartburn.[28]
Vitamin B6 Pyridoxine, pyridoxamine, pyridoxal Water 1.3–1.7 mg Anemia[29] peripheral neuropathy. 100 mg Impairment of proprioception, nerve damage (doses > 100 mg/day)
Vitamin B7 Biotin Water 30.0 µg Dermatitis, enteritis N/D
Vitamin B9 Folic acid, folinic acid Water 400 µg Deficiency during pregnancy is associated with birth defects, such as neural tube defects 1,000 µg May mask symptoms of vitamin B12 deficiency; other effects.
Vitamin B12 Cyanocobalamin, hydroxycobalamin, methylcobalamin Water 2.4 µg Megaloblastic anemia[30] N/D No known toxicity[30]
Vitamin C Ascorbic acid Water 90.0 mg Scurvy 2,000 mg Vitamin C megadosage
Vitamin D Ergocalciferol, cholecalciferol Fat 5.0 µg–10 µg[31] Rickets and Osteomalacia 50 µg Hypervitaminosis D
Vitamin E Tocopherols, tocotrienols Fat 15.0 mg Deficiency is very rare; mild hemolytic anemia in newborn infants.[32] 1,000 mg Increased congestive heart failure seen in one large randomized study.[33]
Vitamin K phylloquinone, menaquinones Fat 120 µg Bleeding diathesis N/D Increases coagulation in patients taking warfarin.[34]
[edit] In nutrition and diseases
Vitamins are essential for the normal growth and development of a multicellular organism. Using the genetic blueprint inherited from its parents, a fetus begins to develop, at the moment of conception, from the nutrients it absorbs. It requires certain vitamins and minerals to be present at certain times. These nutrients facilitate the chemical reactions that produce among other things, skin, bone, and muscle. If there is serious deficiency in one or more of these nutrients, a child may develop a deficiency disease. Even minor deficiencies may cause permanent damage.[35]
For the most part, vitamins are obtained with food, but a few are obtained by other means. For example, microorganisms in the intestine—commonly known as "gut flora"—produce vitamin K and biotin, while one form of vitamin D is synthesized in the skin with the help of the natural ultraviolet wavelength of sunlight. Humans can produce some vitamins from precursors they consume. Examples include vitamin A, produced from beta carotene, and niacin, from the amino acid tryptophan.[22]
Once growth and development are completed, vitamins remain essential nutrients for the healthy maintenance of the cells, tissues, and organs that make up a multicellular organism; they also enable a multicellular life form to efficiently use chemical energy provided by food it eats, and to help process the proteins, carbohydrates, and fats required for respiration.[6]
[edit] Deficiencies
Because human bodies do not store most vitamins, humans must consume them regularly to avoid deficiency. Human bodily stores for different vitamins vary widely; vitamins A, D, and B12 are stored in significant amounts in the human body, mainly in the liver,[32] and an adult human's diet may be deficient in vitamins A and B12 for many months before developing a deficiency condition. Vitamin B3 is not stored in the human body in significant amounts, so stores may only last a couple of weeks.[23][32] Deficiencies of vitamins are classified as either primary or secondary. A primary deficiency occurs when an organism does not get enough of the vitamin in its food. A secondary deficiency may be due to an underlying disorder that prevents or limits the absorption or use of the vitamin, due to a “lifestyle factor”, such as smoking, excessive alcohol consumption, or the use of medications that interfere with the absorption or use of the vitamin.[32] People who eat a varied diet are unlikely to develop a severe primary vitamin deficiency. In contrast, restrictive diets have the potential to cause prolonged vitamin deficits, which may result in often painful and potentially deadly diseases.
Well-known human vitamin deficiencies involve thiamine (beriberi), niacin (pellagra), vitamin C (scurvy) and vitamin D (rickets). In much of the developed world, such deficiencies are rare; this is due to (1) an adequate supply of food; and (2) the addition of vitamins and minerals to common foods, often called fortification.[22][32] In addition to these classical vitamin deficiency diseases, some evidence has also suggested links between vitamin deficiency and a number of different disorders.[36][37]
[edit] Side effects and overdose
In large doses, some vitamins have documented side effects that tend to be more severe with a larger dosage. The likelihood of consuming too much of any vitamin from food is remote, but overdosing from vitamin supplementation does occur. At high enough dosages some vitamins cause side effects such as nausea, diarrhea, and vomiting.[23][38]
When side effects emerge, recovery is often accomplished by reducing the dosage. The concentrations of vitamins an individual can tolerate vary widely, and appear to be related to age and state of health.[39] In the United States, overdose exposure to all formulations of vitamins was reported by 62,562 individuals in 2004 (nearly 80% of these exposures were in children under the age of 6), leading to 53 "major" life-threatening outcomes and 3 deaths[40];a small number in comparison to the 19,250 people who died of unintentional poisoning of all kinds in the U.S. in the same year (2004).[41]
[edit] Supplements
Dietary supplements, often containing vitamins, are used to ensure that adequate amounts of nutrients are obtained on a daily basis, if optimal amounts of the nutrients cannot be obtained through a varied diet. Scientific evidence supporting the benefits of some vitamin supplements is well established for certain health conditions, but others need further study.[42] In some cases, vitamin supplements may have unwanted effects, especially if taken before surgery, with other dietary supplements or medicines, or if the person taking them has certain health conditions.[42] Dietary supplements may also contain levels of vitamins many times higher, and in different forms, than one may ingest through food.[43]
A meta-analysis published in 2006 suggested that Vitamin A and E supplements not only provide no tangible health benefits for generally healthy individuals, but may actually increase mortality, although two large studies included in the analysis involved smokers, for which it was already known that beta-carotene supplements can be harmful.[44] Another study released in May 2009 found that antioxidants such as vitamins C and E may actually curb some benefits of exercise.[45]
[edit] Governmental regulation of vitamin supplements
Most countries place dietary supplements in a special category under the general umbrella of foods, not drugs. This necessitates that the manufacturer, and not the government, be responsible for ensuring that its dietary supplement products are safe before they are marketed. Unlike drug products, which must explicitly be proven safe and effective for their intended use before marketing, there are often no provisions to "approve" dietary supplements for safety or effectiveness before they reach the consumer. Also unlike drug products, manufacturers and distributors of dietary supplements are not generally required to report any claims of injuries or illnesses that may be related to the use of their products.[46][47][42]
[edit] Names in current and previous nomenclatures
Nomenclature of reclassified vitamins Previous name Chemical name Reason for name change[48]
Vitamin B4 Adenine DNA metabolite
Vitamin B8 Adenylic acid DNA metabolite
Vitamin F Essential fatty acids Needed in large quantities (does
not fit the definition of a vitamin).
Vitamin G Riboflavin Reclassified as Vitamin B2
Vitamin H Biotin Reclassified as Vitamin B7
Vitamin J Catechol, Flavin Protein metabolite
Vitamin L1[49] Anthranilic acid Protein metabolite
Vitamin L2[49] Adenylthiomethylpentose RNA metabolite
Vitamin M Folic acid Reclassified as Vitamin B9
Vitamin O Carnitine Protein metabolite
Vitamin P Flavonoids No longer classified as a vitamin
Vitamin PP Niacin Reclassified as Vitamin B3
Vitamin U S-Methylmethionine Protein metabolite
The reason the set of vitamins seems to skip directly from E to K is that the vitamins corresponding to "letters" F-J were either reclassified over time, discarded as false leads, or renamed because of their relationship to "vitamin B", which became a "complex" of vitamins. The German-speaking scientists who isolated and described vitamin K (in addition to naming it as such) did so because the vitamin is intimately involved in the Koagulation of blood following wounding. At the time, most (but not all) of the letters from F through to J were already designated, so the use of the letter K was considered quite reasonable.[48][50] The table on the right lists chemicals that had previously been classified as vitamins, as well as the earlier names of vitamins that later became part of the B-complex.
[edit] See also
* Antioxidant
* Dietary supplement
* Dietetics
* Health freedom movement
* Illnesses related to poor nutrition
* Megavitamin therapy
* Nutrition
o Vitamin deficiency
o Dietary minerals
o Essential amino acids
o Essential nutrients
o Nootropics
o Nutrients
* Orthomolecular medicine
* Pharmacology
* Vitamin poisoning (overdose)
* Whole food supplements
source: wikipedia.org
Getting your vitamins
Eating healthy, balanced meals throughout the day is what will ensure that you take in all the vitamins and nutrients you need to survive. While individuals have different dietary needs, everyone needs the full complement of vitamins in order to live a healthy, disease-free life.
But why do we need vitamins? There are so many and it's hard to keep track of what they do. And why are there so many B vitamins?
The B vitamin: it's value to you
There used to only be one B vitamin, until scientists discovered that it was actually several different chemicals that work together. Over time, scientists have come to understand the B vitamin complex much better. As a result, they have isolated eight different vitamins within the B vitamin family. While they used to consider many more chemicals as part of the B vitamin family, the vitamins that remain (that you need to be taking) are B1, B2, B3, B5, B6, B7, B9, and B12.
Individually, deficiencies in these vitamins may lead to a variety of conditions (depending on which ones are deficient) including unhealthy weight loss, emotional distress, weakness, irregular heartbeat, diarrhea, inflammation of the skin, anemia, and even dementia.
Together, this family of vitamins contributes towards healthy skin, faster metabolism, a better nervous system and immune system, and they can help combat stress and depression. The B vitamin family can really do a lot to improve your life!
The solution
So if you are on a diet and are concerned that you may not be getting enough of the B vitamin complex, you should consider purchasing vitamin supplements to make sure you're getting all the vitamins you need. The cost of going without B vitamins can be tragic, while the benefits of having the full complement of the B vitamin complex is great.
Jeff Lakie
But why do we need vitamins? There are so many and it's hard to keep track of what they do. And why are there so many B vitamins?
The B vitamin: it's value to you
There used to only be one B vitamin, until scientists discovered that it was actually several different chemicals that work together. Over time, scientists have come to understand the B vitamin complex much better. As a result, they have isolated eight different vitamins within the B vitamin family. While they used to consider many more chemicals as part of the B vitamin family, the vitamins that remain (that you need to be taking) are B1, B2, B3, B5, B6, B7, B9, and B12.
Individually, deficiencies in these vitamins may lead to a variety of conditions (depending on which ones are deficient) including unhealthy weight loss, emotional distress, weakness, irregular heartbeat, diarrhea, inflammation of the skin, anemia, and even dementia.
Together, this family of vitamins contributes towards healthy skin, faster metabolism, a better nervous system and immune system, and they can help combat stress and depression. The B vitamin family can really do a lot to improve your life!
The solution
So if you are on a diet and are concerned that you may not be getting enough of the B vitamin complex, you should consider purchasing vitamin supplements to make sure you're getting all the vitamins you need. The cost of going without B vitamins can be tragic, while the benefits of having the full complement of the B vitamin complex is great.
Jeff Lakie
Vitamin D supplementation in early childhood and risk of type 1 diabetes: a systematic review and meta-analysis
ABSTRACT
TOP
ABSTRACT
METHODS
RESULTS
DISCUSSION
CONCLUSION
REFERENCES
Objectives: To assess whether vitamin D supplementation in infancy reduces the risk of type 1 diabetes in later life.
Methods: This was a systematic review and meta-analysis using Medline, Embase, Cinahl, Cochrane Central Register of Controlled Trials and reference lists of retrieved articles. The main outcome measure was development of type 1 diabetes. Controlled trials and observational studies that had assessed the effect of vitamin D supplementation on risk of developing type 1 diabetes were included in the analysis.
Results: Five observational studies (four case-control studies and one cohort study) met the inclusion criteria; no randomised controlled trials were found. Meta-analysis of data from the case-control studies showed that the risk of type 1 diabetes was significantly reduced in infants who were supplemented with vitamin D compared to those who were not supplemented (pooled odds ratio 0.71, 95% CI 0.60 to 0.84). The result of the cohort study was in agreement with that of the meta-analysis. There was also some evidence of a dose-response effect, with those using higher amounts of vitamin D being at lower risk of developing type 1 diabetes. Finally, there was a suggestion that the timing of supplementation might also be important for the subsequent development of type 1 diabetes.
Conclusion: Vitamin D supplementation in early childhood may offer protection against the development of type 1 diabetes. The evidence for this is based on observational studies. Adequately powered, randomised controlled trials with long periods of follow-up are needed to establish causality and the best formulation, dose, duration and period of supplementation.
Type 1 diabetes is characterised by autoimmune destruction of insulin-producing β cells in the pancreas. The specific factors that initiate the autoimmune process are not yet well understood, but β cell destruction often begins during infancy and continues over many months or years.1 By the time type 1 diabetes is diagnosed, about 80% of the β cells have been destroyed.2 Peak incidence occurs around puberty, and the disease is usually diagnosed before age 30.3 It is commonest in people of European descent and affects 2 million people in Europe and North America. There is a marked geographic variation in incidence, with a child in Finland being about 400 times more likely than a child in Venezuela to acquire the disease.4 It is estimated that currently the incidence is increasing by 3% per year.5 Furthermore, it is predicted that by 2010 the incidence of type I diabetes will be 40% higher than it was a decade earlier.6
The fact that people with affected first-degree relatives are a lot more likely to develop type 1 diabetes than the general population points to an important genetic influence.7 However, low concordance among identical twins and the fact that many children with a genetic predisposition to the disease do not develop it suggest that environmental factors are also important.8 One of the environmental factors thought to be protective against the development of type I diabetes, is early supplementation with vitamin D.
Vitamin D is either produced endogenously, through skin exposure to sunlight, or exogenously from ingestion of foods and supplements. Breast milk contains little vitamin D, although this is influenced by the vitamin D status of the mother,9 and this is the reason behind the recommendation for an administered supplement for breastfed infants.10 Furthermore, in northern areas, including the northern United States, Canada and most of Europe, little or no vitamin D is produced in the skin during winter months.11 Even in the summer and at lower latitudes, many infants are so thoroughly protected from sun exposure that they produce little endogenous vitamin D. In addition, there is evidence that over the last few decades the uptake12 as well as the dosage13 of vitamin D supplementation have been declining leading to a resurgence of rickets and hypocalcaemia,14 as well as speculation about the possible role of vitamin D in the increasing incidence of type 1 diabetes and other autoimmune conditions such as rheumatoid arthritis15 and multiple sclerosis.16
Evidence for a causal relationship between vitamin D supplementation and decreased risk of type 1 diabetes comes from experiments in the non-obese diabetic mouse.3 Furthermore, there is evidence of lower plasma 25-hydroxyvitamin D levels at diagnosis of type 1 diabetes compared to controls.17 Moreover, epidemiological evidence suggests that type 1 diabetes is more prevalent in higher latitudes of the tropics and subtropics18 and that there is a seasonal variation in type 1 diabetes with the largest proportion of cases diagnosed during autumn and winter and the lowest during the summer.19 In addition, epidemiological studies20 suggest that supplementation with vitamin D in infants might be important in conferring protection against the development of type 1 diabetes.
In this study, we sought to explore the potential association between vitamin D supplementation in early childhood and reduced risk of type 1 diabetes by conducting a systematic review and meta-analysis of human trials and observational studies.
METHODS
TOP
ABSTRACT
METHODS
RESULTS
DISCUSSION
CONCLUSION
REFERENCES
Types of studies
We searched for randomised controlled trials and observational studies. We included observational studies if they: (1) compared risk of type 1 diabetes in people who were supplemented with vitamin D with risk in those who were not supplemented, (2) had controlled for potential confounders by matching in the study design or had used risk adjustment in the analysis and (3) had provided sufficient data to allow the reconstruction of 2 by 2 tables or to determine relative risks (RR) or odds ratios (OR) with 95% confidence intervals (95% CI). Subjects given cod liver oil were considered to have been supplemented with vitamin D in line with previous publications.13 21 22
Search strategy
We systematically searched Medline (1966–June 2007), Embase (1980–June 2007), Cinahl (1982–June 2007) and the Cochrane Central Register of Controlled Trials (issue 2, 2007) for both English and non-English language articles by entering "vitamin D", "vitamin D2", "vitamin D3", "ergocalciferol", "alfacalcidol", "alphacalcidol", "hydroxycholecalciferol", "calcitriol", "dihydroxycholecalciferol", "colecalciferol", "cholecalciferol" and "diabetes". No limits were used.
We then searched the reference lists of all relevant articles retrieved from the computerised database search to find other potentially relevant articles. The titles and/or abstracts of all identified studies were reviewed and full manuscripts obtained for those that appeared potentially relevant.
Assessment of study eligibility
Each article was independently assessed by two reviewers for eligibility using the inclusion criteria above. Any disagreement among reviewers was discussed and agreement reached by consensus.
Assessment of methodological quality
Two investigators independently rated the methodological quality of selected studies using the Critical Appraisal Skills Programme (PHRU, Oxford, UK) tool for case-control studies.23 We recorded each quality assessment criterion as being "met", "unmet" or "unclear". However, as several criteria were used to assess validity, these were summarised to derive an overall assessment of how valid the results of each study were by grading them as A (low risk of bias), B (moderate risk of bias) or C (high risk of bias) according to published criteria.24
Data extraction
A data abstraction form was developed and used to extract information on the relevant features and results of included studies. Two reviewers independently extracted and recorded data using a predefined checklist. When data were missing or unclear in a paper, attempts were made to contact the authors for more information.
Statistical methods
Statistical analyses were performed using StatsDirect statistical software (v 2.6.1; StatsDirect, Altrincham, UK). Individual OR and their 95% CI from each case-control study were calculated. Where possible, a pooled OR with 95% CI was calculated. The meta-analysis was conducted using the Mantel-Haenszel method.25
Heterogeneity
The statistical validity of combining the results of the various trials was assessed by examining the homogeneity of the outcomes from the various trials. This was carried out by: (1) using the Cochran Q test and (2) inspection of the graphical display.
RESULTS
TOP
ABSTRACT
METHODS
RESULTS
DISCUSSION
CONCLUSION
REFERENCES
We identified 19 potentially relevant articles3 13 17 19–22 26–37 on the association between vitamin D supplementation and the development of type 1 diabetes (fig 1). Five studies were identified that satisfied the inclusion criteria and these were included in the review.13 20–22 26 Four of them were case-control studies20–22 26 and one was a cohort study.13 No randomised control trials were identified. The study by Littorin et al17 was excluded because it did not compare rates in those exposed to or not supplemented with vitamin D, but rather the levels of vitamin D over time in those with type 1 diabetes. The study by Visalli et al36 was excluded because it did not provide enough data for construction of a 2 by 2 table to determine OR and repeated attempts to get more information from the authors proved unsuccessful.
Figure 01
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Figure 1 Flow chart of studies through the review process.
Methodological quality of included studies
Due to the retrospective design, all the case-control studies were prone to recall bias. All of the included case-control studies except that by Tenconi et al26 used healthy children whose non-diabetic status was not specifically confirmed. However, as type 1 diabetes is unlikely to be asymptomatic for a long period of time, the possibility of misclassification for some controls is small. Most case-control studies used cases up to 15 years of age,20–22 but Tenconi et al26 used a higher cut-off value (30 years). None of the case-control studies included used an objective method to ascertain the vitamin D status of cases or controls, and none attempted to quantify the total amount of vitamin D intake from the diet or that from exposure to the sun. In addition, none of the studies looked at the ethnic backgrounds of cases versus controls. A summary of the methodology of the included case-control studies is shown in table 1.
View this table:
in this window | in a new window
Table 1 Summary of methodology of case-control studies
The methodological quality of each study was summarised using the categories described above. All case-control studies included were graded B. The cohort study13 was graded B because it did not use an objective method of assessing the vitamin D status of cases and controls and because no mention of blinding to the outcomes was mentioned. Furthermore, although a fair number of confounding factors were accounted for, some important ones were not, for example duration of breastfeeding and age at weaning.
Association between vitamin D supplementation and type 1 diabetes
Ever supplemented versus never supplemented Three of the included case-control studies20 21 26 provided enough data on the risk of developing type 1 diabetes in infants who were supplemented with vitamin D versus those not being supplemented, to allow a meta-analysis to be performed on this variable. After contacting the authors of the final case-control study,22 enough information was provided to allow inclusion of this study in the meta-analysis. For the EURODIAB study20 we followed the example of the authors and used each centre as a separate entry to account for the heterogeneity between centres and also to aid in the assessment of heterogeneity in the global sample. The total number of participants in included studies was 6455 (1429 cases and 5026 controls). In the main analysis using the fixed effects model (fig 2), the risk of developing type 1 diabetes was significantly reduced in participants who were supplemented with vitamin D (OR 0.71, 95% CI 0.60 to 0.84). The results of these studies appeared to be reasonably homogeneous and the test for heterogeneity was negative (p = 0.13).
Figure 02
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Figure 2 Odds ratios (95% CI) of effect of vitamin D supplementation in infancy on development of type 1 diabetes.
The result of the meta-analysis is in agreement with the main outcome from the cohort study.13 In the latter study, the rate risk for regular versus no supplementation was 0.12 (95% CI 0.03 to 0.51) and for irregular versus no supplementation 0.16 (95% CI 0.04 to 0.74).
Type of supplement used There were not enough data in the primary studies to allow comparison of the groups based on type of supplement used.
Dosage of supplementation In the majority of studies no information was given about the dosage of supplements used. Stene et al (2003)22 speculated that the cod liver oil and the different vitamin D supplements used in Norway at the time in question would contain 10 µg of vitamin D. They divided their patients into those who had taken cod liver oil and those who had "other" forms of vitamin D. Concentrating on the group that had the cod liver oil, one can see that as the frequency of supplementation increases from one to four times per week to more than five times per week, the OR of developing type 1 diabetes decreases (OR 0.81, 95% CI 0.55 to 1.19 and OR 0.74, 95% CI 0.56 to 0.99, respectively). There is a negligible change in OR in those that had the "other" types of vitamin D supplement (OR 0.99, 95% CI 0.69 to 1.42 and OR 0.97, 95% CI 0.73 to 1.29, respectively).
There is evidence from the Hypponen study13 that those who used the recommended dose of 2000 IU regularly had an RR of 0.22 (95% CI 0.05 to 0.89) compared with those who regularly used less than the recommended dose. Furthermore, the authors showed that with an increase in regularity of supplementation as well as dose used, the incidence of type 1 diabetes tended to decrease.13 Finally, they reported that those with suspected rickets had an increased risk of developing type 1 diabetes, although the result was not statistically significant (RR 3.0, 95% CI 1.0 to 9.0).
Duration of supplementation Only the EURODIAB study20 considered duration of supplementation as a factor. Although there was some improvement in the OR, they did not find any significant difference between those who were supplemented for less than a year (OR 0.69, 95% CI 0.52 to 0.93) and those who were supplemented for more than a year (OR 0.64, 95% CI 0.47 to 0.89).
Timing of supplementation The report by Stene et al (2003)22 is the only one of the identified studies that looked at the effect of the time of starting supplementation with vitamin D. It appears that those who had cod liver oil between 7 and 12 months of age had lower chances of developing type 1 diabetes in later life compared to those who were supplemented between 0 and 6 months of age (OR 0.55, 95% CI 0.31 to 0.96 and OR 0.80, 95% CI 0.61 to 1.06, respectively). A similar, albeit less impressive, result was obtained for the "other" vitamin D supplements (OR 0.98, 95% CI 0.65 to 1.49 and OR 1.02, 95% CI 0.77 to 1.35, respectively).
DISCUSSION
TOP
ABSTRACT
METHODS
RESULTS
DISCUSSION
CONCLUSION
REFERENCES
The results of this study suggest that vitamin D supplementation in infancy may offer protection against the development of type 1 diabetes. Meta-analysis of data from four studies, which included children from many different European countries, indicated that children being supplemented had a 29% reduction in risk of developing type 1 diabetes compared with their peers who were not being supplemented. The reduction in risk was also demonstrated in a cohort study.13 The study by Stene et al (2003)22 reported no association between vitamin D supplementation and subsequent diabetes development. Although it was not clear in the paper how many of these patients used both vitamin D and cod liver oil and how many used neither of the two, we managed to obtain this information by contacting the authors, something that allowed inclusion of the study in the meta-analysis. Some studies were not able to show an association with a reduction in risk of type 1 diabetes,21 36 but none of them were associated with an increased risk.
Furthermore, there is evidence of a dose-response effect. The cohort study13 showed that those who had rickets diagnosed earlier in life (and were thus more likely to be those with the lowest amounts of vitamin D) were more likely to develop type 1 diabetes. In addition, those that were supplemented more regularly or had higher doses of vitamin D supplements, displayed a reduced risk of developing type 1 diabetes. The positive findings with increasing frequency of use were also confirmed in one of the case-control studies22 that looked at this variable.
One of the included studies22 suggests that supplementation from 7 to 12 months of age is more beneficial than supplementation from birth to 6 months. However, the former could be a marker of longer supplementation. At the same time, infants of mothers who are themselves vitamin D deficient would be at an increased risk of hypocalcaemic complications in the first few months of life,14 something that would necessitate earlier supplementation. Finally, there are many unexplored variables including an overall lack of accurate, reliable feeding information which could explain this observation.
The exact mechanism by which vitamin D supplementation protects against type 1 diabetes is unclear, but it has been suggested that this is likely to be through the prevention of hypovitaminosis D.27 The identification of receptors for the active form of vitamin D in both β cells and immune cells27 has led to a number of studies for the delineation of these pathways. There is evidence for a physiological role for vitamin D in the immune system, and also for a protective effect of the vitamin from cytokine-induced β cell dysfunction.27
Strengths and weaknesses of the study
Our review included studies from many European countries and included four case-control studies and a cohort study. We searched multiple databases and reference lists to minimise the chance of missing relevant studies. We minimised subjectivity by carrying out study selection, data extraction and quality assessment in duplicate. However, the validity of the results of a systematic review depends on the validity of the included studies. Many of the included studies failed to take all the steps necessary to avoid bias. Our conclusions were, therefore, limited by the quality of included studies and the information provided.
What is already known on this subject
* Observational studies have suggested that vitamin D supplementation may reduce the risk of type 1 diabetes, but the results of the studies have been inconsistent.
What this study adds
* Meta-analysis of the results of observational studies suggest that the risk of type 1 diabetes is significantly reduced in those who were supplemented in childhood with vitamin D compared to those who were not supplemented (odds ratio 0.71, 95% CI 0.60 to 0.84).
* Randomised controlled trials with long periods of follow-up are needed to establish causality and the best formulation, dose, duration and period of supplementation.
The included case-control studies are subject to recall bias. If, for instance, parents of children with type 1 diabetes could recall more accurately that their children were not supplemented with vitamin D in infancy, bias could result which would tend to inflate the association in favour of supplementation. Furthermore, none of the case-control studies included used an objective method to ascertain the vitamin D status of cases or controls, and none attempted to quantify the total amount of vitamin D intake from the diet or that from exposure to the sun. In addition, use of healthy controls without prior checking of non-diabetic status could lead to some misclassification. Case-control studies are also susceptible to bias because other risk factors of type 1 diabetes could be unbalanced across children who were supplemented and those who were not, with breastfeeding being an obvious example. Some of the included studies20–22 26 made an attempt to control for breastfeeding (<3 months), but no information is given about volumes of formula milk consumed or amount of vitamin D in the formula milk. While the individual studies tried to control for a number of potential confounding factors, it is possible that a number of other confounding factors could have been unbalanced across children who were supplemented and those who were not. Finally, we considered those who used cod liver oil as a supplement to be similar to those receiving other forms of vitamin D. This could lead to erroneous conclusions as cod liver oil contains other components that could be protective against type 1 diabetes.
CONCLUSION
TOP
ABSTRACT
METHODS
RESULTS
DISCUSSION
CONCLUSION
REFERENCES
In conclusion, there is evidence from observational studies that vitamin D supplementation in infancy might be protective against the development of type 1 diabetes. Despite limitations, the Hill criteria for causality38 seem to be fulfilled. However, for concrete conclusions to be reached, adequately powered, randomised controlled trials with long periods of follow-up would be required to establish causality and the best formulation, dose, duration and period of supplementation.
C S Zipitis1, A K Akobeng2
1 Department of Paediatrics, Stockport NHS Foundation Trust, Stockport, UK
2 Department of Paediatric Gastroenterology, Central Manchester and Manchester Children’s University Hospitals, Booth Hall Children’s Hospital, Manchester, UK
C S Zipitis, Department of Paediatrics, Stockport NHS Foundation Trust, Poplar Grove, Stockport SK2 7JE, UK; czipitis@hotmail.com
Accepted 17 January 2008
TOP
ABSTRACT
METHODS
RESULTS
DISCUSSION
CONCLUSION
REFERENCES
Objectives: To assess whether vitamin D supplementation in infancy reduces the risk of type 1 diabetes in later life.
Methods: This was a systematic review and meta-analysis using Medline, Embase, Cinahl, Cochrane Central Register of Controlled Trials and reference lists of retrieved articles. The main outcome measure was development of type 1 diabetes. Controlled trials and observational studies that had assessed the effect of vitamin D supplementation on risk of developing type 1 diabetes were included in the analysis.
Results: Five observational studies (four case-control studies and one cohort study) met the inclusion criteria; no randomised controlled trials were found. Meta-analysis of data from the case-control studies showed that the risk of type 1 diabetes was significantly reduced in infants who were supplemented with vitamin D compared to those who were not supplemented (pooled odds ratio 0.71, 95% CI 0.60 to 0.84). The result of the cohort study was in agreement with that of the meta-analysis. There was also some evidence of a dose-response effect, with those using higher amounts of vitamin D being at lower risk of developing type 1 diabetes. Finally, there was a suggestion that the timing of supplementation might also be important for the subsequent development of type 1 diabetes.
Conclusion: Vitamin D supplementation in early childhood may offer protection against the development of type 1 diabetes. The evidence for this is based on observational studies. Adequately powered, randomised controlled trials with long periods of follow-up are needed to establish causality and the best formulation, dose, duration and period of supplementation.
Type 1 diabetes is characterised by autoimmune destruction of insulin-producing β cells in the pancreas. The specific factors that initiate the autoimmune process are not yet well understood, but β cell destruction often begins during infancy and continues over many months or years.1 By the time type 1 diabetes is diagnosed, about 80% of the β cells have been destroyed.2 Peak incidence occurs around puberty, and the disease is usually diagnosed before age 30.3 It is commonest in people of European descent and affects 2 million people in Europe and North America. There is a marked geographic variation in incidence, with a child in Finland being about 400 times more likely than a child in Venezuela to acquire the disease.4 It is estimated that currently the incidence is increasing by 3% per year.5 Furthermore, it is predicted that by 2010 the incidence of type I diabetes will be 40% higher than it was a decade earlier.6
The fact that people with affected first-degree relatives are a lot more likely to develop type 1 diabetes than the general population points to an important genetic influence.7 However, low concordance among identical twins and the fact that many children with a genetic predisposition to the disease do not develop it suggest that environmental factors are also important.8 One of the environmental factors thought to be protective against the development of type I diabetes, is early supplementation with vitamin D.
Vitamin D is either produced endogenously, through skin exposure to sunlight, or exogenously from ingestion of foods and supplements. Breast milk contains little vitamin D, although this is influenced by the vitamin D status of the mother,9 and this is the reason behind the recommendation for an administered supplement for breastfed infants.10 Furthermore, in northern areas, including the northern United States, Canada and most of Europe, little or no vitamin D is produced in the skin during winter months.11 Even in the summer and at lower latitudes, many infants are so thoroughly protected from sun exposure that they produce little endogenous vitamin D. In addition, there is evidence that over the last few decades the uptake12 as well as the dosage13 of vitamin D supplementation have been declining leading to a resurgence of rickets and hypocalcaemia,14 as well as speculation about the possible role of vitamin D in the increasing incidence of type 1 diabetes and other autoimmune conditions such as rheumatoid arthritis15 and multiple sclerosis.16
Evidence for a causal relationship between vitamin D supplementation and decreased risk of type 1 diabetes comes from experiments in the non-obese diabetic mouse.3 Furthermore, there is evidence of lower plasma 25-hydroxyvitamin D levels at diagnosis of type 1 diabetes compared to controls.17 Moreover, epidemiological evidence suggests that type 1 diabetes is more prevalent in higher latitudes of the tropics and subtropics18 and that there is a seasonal variation in type 1 diabetes with the largest proportion of cases diagnosed during autumn and winter and the lowest during the summer.19 In addition, epidemiological studies20 suggest that supplementation with vitamin D in infants might be important in conferring protection against the development of type 1 diabetes.
In this study, we sought to explore the potential association between vitamin D supplementation in early childhood and reduced risk of type 1 diabetes by conducting a systematic review and meta-analysis of human trials and observational studies.
METHODS
TOP
ABSTRACT
METHODS
RESULTS
DISCUSSION
CONCLUSION
REFERENCES
Types of studies
We searched for randomised controlled trials and observational studies. We included observational studies if they: (1) compared risk of type 1 diabetes in people who were supplemented with vitamin D with risk in those who were not supplemented, (2) had controlled for potential confounders by matching in the study design or had used risk adjustment in the analysis and (3) had provided sufficient data to allow the reconstruction of 2 by 2 tables or to determine relative risks (RR) or odds ratios (OR) with 95% confidence intervals (95% CI). Subjects given cod liver oil were considered to have been supplemented with vitamin D in line with previous publications.13 21 22
Search strategy
We systematically searched Medline (1966–June 2007), Embase (1980–June 2007), Cinahl (1982–June 2007) and the Cochrane Central Register of Controlled Trials (issue 2, 2007) for both English and non-English language articles by entering "vitamin D", "vitamin D2", "vitamin D3", "ergocalciferol", "alfacalcidol", "alphacalcidol", "hydroxycholecalciferol", "calcitriol", "dihydroxycholecalciferol", "colecalciferol", "cholecalciferol" and "diabetes". No limits were used.
We then searched the reference lists of all relevant articles retrieved from the computerised database search to find other potentially relevant articles. The titles and/or abstracts of all identified studies were reviewed and full manuscripts obtained for those that appeared potentially relevant.
Assessment of study eligibility
Each article was independently assessed by two reviewers for eligibility using the inclusion criteria above. Any disagreement among reviewers was discussed and agreement reached by consensus.
Assessment of methodological quality
Two investigators independently rated the methodological quality of selected studies using the Critical Appraisal Skills Programme (PHRU, Oxford, UK) tool for case-control studies.23 We recorded each quality assessment criterion as being "met", "unmet" or "unclear". However, as several criteria were used to assess validity, these were summarised to derive an overall assessment of how valid the results of each study were by grading them as A (low risk of bias), B (moderate risk of bias) or C (high risk of bias) according to published criteria.24
Data extraction
A data abstraction form was developed and used to extract information on the relevant features and results of included studies. Two reviewers independently extracted and recorded data using a predefined checklist. When data were missing or unclear in a paper, attempts were made to contact the authors for more information.
Statistical methods
Statistical analyses were performed using StatsDirect statistical software (v 2.6.1; StatsDirect, Altrincham, UK). Individual OR and their 95% CI from each case-control study were calculated. Where possible, a pooled OR with 95% CI was calculated. The meta-analysis was conducted using the Mantel-Haenszel method.25
Heterogeneity
The statistical validity of combining the results of the various trials was assessed by examining the homogeneity of the outcomes from the various trials. This was carried out by: (1) using the Cochran Q test and (2) inspection of the graphical display.
RESULTS
TOP
ABSTRACT
METHODS
RESULTS
DISCUSSION
CONCLUSION
REFERENCES
We identified 19 potentially relevant articles3 13 17 19–22 26–37 on the association between vitamin D supplementation and the development of type 1 diabetes (fig 1). Five studies were identified that satisfied the inclusion criteria and these were included in the review.13 20–22 26 Four of them were case-control studies20–22 26 and one was a cohort study.13 No randomised control trials were identified. The study by Littorin et al17 was excluded because it did not compare rates in those exposed to or not supplemented with vitamin D, but rather the levels of vitamin D over time in those with type 1 diabetes. The study by Visalli et al36 was excluded because it did not provide enough data for construction of a 2 by 2 table to determine OR and repeated attempts to get more information from the authors proved unsuccessful.
Figure 01
View larger version (21K):
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Figure 1 Flow chart of studies through the review process.
Methodological quality of included studies
Due to the retrospective design, all the case-control studies were prone to recall bias. All of the included case-control studies except that by Tenconi et al26 used healthy children whose non-diabetic status was not specifically confirmed. However, as type 1 diabetes is unlikely to be asymptomatic for a long period of time, the possibility of misclassification for some controls is small. Most case-control studies used cases up to 15 years of age,20–22 but Tenconi et al26 used a higher cut-off value (30 years). None of the case-control studies included used an objective method to ascertain the vitamin D status of cases or controls, and none attempted to quantify the total amount of vitamin D intake from the diet or that from exposure to the sun. In addition, none of the studies looked at the ethnic backgrounds of cases versus controls. A summary of the methodology of the included case-control studies is shown in table 1.
View this table:
in this window | in a new window
Table 1 Summary of methodology of case-control studies
The methodological quality of each study was summarised using the categories described above. All case-control studies included were graded B. The cohort study13 was graded B because it did not use an objective method of assessing the vitamin D status of cases and controls and because no mention of blinding to the outcomes was mentioned. Furthermore, although a fair number of confounding factors were accounted for, some important ones were not, for example duration of breastfeeding and age at weaning.
Association between vitamin D supplementation and type 1 diabetes
Ever supplemented versus never supplemented Three of the included case-control studies20 21 26 provided enough data on the risk of developing type 1 diabetes in infants who were supplemented with vitamin D versus those not being supplemented, to allow a meta-analysis to be performed on this variable. After contacting the authors of the final case-control study,22 enough information was provided to allow inclusion of this study in the meta-analysis. For the EURODIAB study20 we followed the example of the authors and used each centre as a separate entry to account for the heterogeneity between centres and also to aid in the assessment of heterogeneity in the global sample. The total number of participants in included studies was 6455 (1429 cases and 5026 controls). In the main analysis using the fixed effects model (fig 2), the risk of developing type 1 diabetes was significantly reduced in participants who were supplemented with vitamin D (OR 0.71, 95% CI 0.60 to 0.84). The results of these studies appeared to be reasonably homogeneous and the test for heterogeneity was negative (p = 0.13).
Figure 02
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Figure 2 Odds ratios (95% CI) of effect of vitamin D supplementation in infancy on development of type 1 diabetes.
The result of the meta-analysis is in agreement with the main outcome from the cohort study.13 In the latter study, the rate risk for regular versus no supplementation was 0.12 (95% CI 0.03 to 0.51) and for irregular versus no supplementation 0.16 (95% CI 0.04 to 0.74).
Type of supplement used There were not enough data in the primary studies to allow comparison of the groups based on type of supplement used.
Dosage of supplementation In the majority of studies no information was given about the dosage of supplements used. Stene et al (2003)22 speculated that the cod liver oil and the different vitamin D supplements used in Norway at the time in question would contain 10 µg of vitamin D. They divided their patients into those who had taken cod liver oil and those who had "other" forms of vitamin D. Concentrating on the group that had the cod liver oil, one can see that as the frequency of supplementation increases from one to four times per week to more than five times per week, the OR of developing type 1 diabetes decreases (OR 0.81, 95% CI 0.55 to 1.19 and OR 0.74, 95% CI 0.56 to 0.99, respectively). There is a negligible change in OR in those that had the "other" types of vitamin D supplement (OR 0.99, 95% CI 0.69 to 1.42 and OR 0.97, 95% CI 0.73 to 1.29, respectively).
There is evidence from the Hypponen study13 that those who used the recommended dose of 2000 IU regularly had an RR of 0.22 (95% CI 0.05 to 0.89) compared with those who regularly used less than the recommended dose. Furthermore, the authors showed that with an increase in regularity of supplementation as well as dose used, the incidence of type 1 diabetes tended to decrease.13 Finally, they reported that those with suspected rickets had an increased risk of developing type 1 diabetes, although the result was not statistically significant (RR 3.0, 95% CI 1.0 to 9.0).
Duration of supplementation Only the EURODIAB study20 considered duration of supplementation as a factor. Although there was some improvement in the OR, they did not find any significant difference between those who were supplemented for less than a year (OR 0.69, 95% CI 0.52 to 0.93) and those who were supplemented for more than a year (OR 0.64, 95% CI 0.47 to 0.89).
Timing of supplementation The report by Stene et al (2003)22 is the only one of the identified studies that looked at the effect of the time of starting supplementation with vitamin D. It appears that those who had cod liver oil between 7 and 12 months of age had lower chances of developing type 1 diabetes in later life compared to those who were supplemented between 0 and 6 months of age (OR 0.55, 95% CI 0.31 to 0.96 and OR 0.80, 95% CI 0.61 to 1.06, respectively). A similar, albeit less impressive, result was obtained for the "other" vitamin D supplements (OR 0.98, 95% CI 0.65 to 1.49 and OR 1.02, 95% CI 0.77 to 1.35, respectively).
DISCUSSION
TOP
ABSTRACT
METHODS
RESULTS
DISCUSSION
CONCLUSION
REFERENCES
The results of this study suggest that vitamin D supplementation in infancy may offer protection against the development of type 1 diabetes. Meta-analysis of data from four studies, which included children from many different European countries, indicated that children being supplemented had a 29% reduction in risk of developing type 1 diabetes compared with their peers who were not being supplemented. The reduction in risk was also demonstrated in a cohort study.13 The study by Stene et al (2003)22 reported no association between vitamin D supplementation and subsequent diabetes development. Although it was not clear in the paper how many of these patients used both vitamin D and cod liver oil and how many used neither of the two, we managed to obtain this information by contacting the authors, something that allowed inclusion of the study in the meta-analysis. Some studies were not able to show an association with a reduction in risk of type 1 diabetes,21 36 but none of them were associated with an increased risk.
Furthermore, there is evidence of a dose-response effect. The cohort study13 showed that those who had rickets diagnosed earlier in life (and were thus more likely to be those with the lowest amounts of vitamin D) were more likely to develop type 1 diabetes. In addition, those that were supplemented more regularly or had higher doses of vitamin D supplements, displayed a reduced risk of developing type 1 diabetes. The positive findings with increasing frequency of use were also confirmed in one of the case-control studies22 that looked at this variable.
One of the included studies22 suggests that supplementation from 7 to 12 months of age is more beneficial than supplementation from birth to 6 months. However, the former could be a marker of longer supplementation. At the same time, infants of mothers who are themselves vitamin D deficient would be at an increased risk of hypocalcaemic complications in the first few months of life,14 something that would necessitate earlier supplementation. Finally, there are many unexplored variables including an overall lack of accurate, reliable feeding information which could explain this observation.
The exact mechanism by which vitamin D supplementation protects against type 1 diabetes is unclear, but it has been suggested that this is likely to be through the prevention of hypovitaminosis D.27 The identification of receptors for the active form of vitamin D in both β cells and immune cells27 has led to a number of studies for the delineation of these pathways. There is evidence for a physiological role for vitamin D in the immune system, and also for a protective effect of the vitamin from cytokine-induced β cell dysfunction.27
Strengths and weaknesses of the study
Our review included studies from many European countries and included four case-control studies and a cohort study. We searched multiple databases and reference lists to minimise the chance of missing relevant studies. We minimised subjectivity by carrying out study selection, data extraction and quality assessment in duplicate. However, the validity of the results of a systematic review depends on the validity of the included studies. Many of the included studies failed to take all the steps necessary to avoid bias. Our conclusions were, therefore, limited by the quality of included studies and the information provided.
What is already known on this subject
* Observational studies have suggested that vitamin D supplementation may reduce the risk of type 1 diabetes, but the results of the studies have been inconsistent.
What this study adds
* Meta-analysis of the results of observational studies suggest that the risk of type 1 diabetes is significantly reduced in those who were supplemented in childhood with vitamin D compared to those who were not supplemented (odds ratio 0.71, 95% CI 0.60 to 0.84).
* Randomised controlled trials with long periods of follow-up are needed to establish causality and the best formulation, dose, duration and period of supplementation.
The included case-control studies are subject to recall bias. If, for instance, parents of children with type 1 diabetes could recall more accurately that their children were not supplemented with vitamin D in infancy, bias could result which would tend to inflate the association in favour of supplementation. Furthermore, none of the case-control studies included used an objective method to ascertain the vitamin D status of cases or controls, and none attempted to quantify the total amount of vitamin D intake from the diet or that from exposure to the sun. In addition, use of healthy controls without prior checking of non-diabetic status could lead to some misclassification. Case-control studies are also susceptible to bias because other risk factors of type 1 diabetes could be unbalanced across children who were supplemented and those who were not, with breastfeeding being an obvious example. Some of the included studies20–22 26 made an attempt to control for breastfeeding (<3 months), but no information is given about volumes of formula milk consumed or amount of vitamin D in the formula milk. While the individual studies tried to control for a number of potential confounding factors, it is possible that a number of other confounding factors could have been unbalanced across children who were supplemented and those who were not. Finally, we considered those who used cod liver oil as a supplement to be similar to those receiving other forms of vitamin D. This could lead to erroneous conclusions as cod liver oil contains other components that could be protective against type 1 diabetes.
CONCLUSION
TOP
ABSTRACT
METHODS
RESULTS
DISCUSSION
CONCLUSION
REFERENCES
In conclusion, there is evidence from observational studies that vitamin D supplementation in infancy might be protective against the development of type 1 diabetes. Despite limitations, the Hill criteria for causality38 seem to be fulfilled. However, for concrete conclusions to be reached, adequately powered, randomised controlled trials with long periods of follow-up would be required to establish causality and the best formulation, dose, duration and period of supplementation.
C S Zipitis1, A K Akobeng2
1 Department of Paediatrics, Stockport NHS Foundation Trust, Stockport, UK
2 Department of Paediatric Gastroenterology, Central Manchester and Manchester Children’s University Hospitals, Booth Hall Children’s Hospital, Manchester, UK
C S Zipitis, Department of Paediatrics, Stockport NHS Foundation Trust, Poplar Grove, Stockport SK2 7JE, UK; czipitis@hotmail.com
Accepted 17 January 2008
Feeding Chickens Chicken Feed Vitamin and Mineral Supplements
Humans often take daily vitamin supplements. Depending on how they are managed, your chicken flock may need vitamin and mineral feed supplements, as well. Common, necessary feed supplements include calcium, grit, phosphorus, and salt, not including some vitamins. The following is a list of a few chicken feed supplements that are readily available to small-scale poultry farmers and chicken hobbyists. We also offer a free article with complete chicken feeding directions.
Each of the following supplements are rating on a scale of 1 to 5, with 1 being "Not necessary" and 5 being "Crucial".
Calcium. 5 (for layers) and 2 (for non-layers). Calcium is needed by laying hens to form strong, sturdy eggshells. Hens without proper amounts of calcium lay thin-shelled eggs, or eggs with no shell at all! The amount of calcium a hen needs varies with her age, diet, health, breed, and size. Older hens need more calcium than their younger counterparts, and hens in hot weather need extra calcium concentrations in their feed since they are eating less due to the heat and might not be getting all the calcium they need. Since eggshells consist mostly of calcium carbonate, oyster shells and ground up limestone are good sources of supplementary calcium. Make sure you are not purchasing dolomite limestone, since this is harmful to egg production!
Salt. 2. Be extremely careful when giving chickens this occasionally fatal supplement! Most feeds have sufficient amounts of salt, so supplements of this should not be needed. Although minute amounts of salt are vital for a chicken's health, too much salt given to a flock when there is not enough water available can be poisonous. In warm weather, be sure that water dishes remain full, and in winter make sure that water does not freeze (or remove salt supplements from feed).
Phosphorous. 2. This supplement is needed so that the chickens can metabolize calcium (and calcium is likewise needed for the proper digestion of phosphorous). Range fed chickens do get phosphorus from beetles, but they probably don't get enough.
Grit. 4. Since chickens don't have any teeth, this important supplement is needed for proper digestion. Grit is usually sold as small pebbles or large grains of sand. These hard objects are eaten by the chickens and lodged in their gizzard. When grains, grass, and other fibrous/hard vegetation are eaten, it passes through the rocks in the gizzard where it is ground up between the stone (much like teeth). Grit should always be available, even if you're not feeding the flock heavily with grains and vegetables. Free-ranged chickens shouldn't need this supplement.
Vitamin D. 5. This vitamin is related to the assimilation of calcium and phosphorus and is needed for proper egg production. Deficiencies cause weak, thin eggshells. Vitamin D is found in cod liver oil and plenty of sunlight. Although this is a crucial vitamin, you shouldn't need to feed extra amounts unless your chickens aren't getting enough via sunlight or their feed.
Vitamin A. 2. Vitamin A is essential for good hatch-ability and chick viability (attention chicken breeders!). It comes from fresh grass and other vegetation, yellow corn, and cod liver oil. Most feeds include proper amounts of this.
Riboflavin. 3. This is one of the B vitamins and is often deficient in normal poultry feeds. If you are a breeder, deficiency of this vitamin causes embryo death during the early stages of incubation. This important vitamin is found in dairy products, yeast, liver, and plenty of leafy green vegetables.
Vitamin E. 3. Needed for proper health and protection from diseases, vitamin E is found in fresh greens, wheat germ oil, and whole grains (such as oats, corn, wheat, barley, etc.)
As you can see, the majority of the vitamins needed by chickens are found in sunlight and fresh greens. This is why free ranged chickens (or chickens in confined-free-range-systems) are so healthy. Plenty of clean air, fresh food, sunlight, and green veggies along with a few choice supplements should keep your chickens living as long as Methuselah!
poultryOne.com
Each of the following supplements are rating on a scale of 1 to 5, with 1 being "Not necessary" and 5 being "Crucial".
Calcium. 5 (for layers) and 2 (for non-layers). Calcium is needed by laying hens to form strong, sturdy eggshells. Hens without proper amounts of calcium lay thin-shelled eggs, or eggs with no shell at all! The amount of calcium a hen needs varies with her age, diet, health, breed, and size. Older hens need more calcium than their younger counterparts, and hens in hot weather need extra calcium concentrations in their feed since they are eating less due to the heat and might not be getting all the calcium they need. Since eggshells consist mostly of calcium carbonate, oyster shells and ground up limestone are good sources of supplementary calcium. Make sure you are not purchasing dolomite limestone, since this is harmful to egg production!
Salt. 2. Be extremely careful when giving chickens this occasionally fatal supplement! Most feeds have sufficient amounts of salt, so supplements of this should not be needed. Although minute amounts of salt are vital for a chicken's health, too much salt given to a flock when there is not enough water available can be poisonous. In warm weather, be sure that water dishes remain full, and in winter make sure that water does not freeze (or remove salt supplements from feed).
Phosphorous. 2. This supplement is needed so that the chickens can metabolize calcium (and calcium is likewise needed for the proper digestion of phosphorous). Range fed chickens do get phosphorus from beetles, but they probably don't get enough.
Grit. 4. Since chickens don't have any teeth, this important supplement is needed for proper digestion. Grit is usually sold as small pebbles or large grains of sand. These hard objects are eaten by the chickens and lodged in their gizzard. When grains, grass, and other fibrous/hard vegetation are eaten, it passes through the rocks in the gizzard where it is ground up between the stone (much like teeth). Grit should always be available, even if you're not feeding the flock heavily with grains and vegetables. Free-ranged chickens shouldn't need this supplement.
Vitamin D. 5. This vitamin is related to the assimilation of calcium and phosphorus and is needed for proper egg production. Deficiencies cause weak, thin eggshells. Vitamin D is found in cod liver oil and plenty of sunlight. Although this is a crucial vitamin, you shouldn't need to feed extra amounts unless your chickens aren't getting enough via sunlight or their feed.
Vitamin A. 2. Vitamin A is essential for good hatch-ability and chick viability (attention chicken breeders!). It comes from fresh grass and other vegetation, yellow corn, and cod liver oil. Most feeds include proper amounts of this.
Riboflavin. 3. This is one of the B vitamins and is often deficient in normal poultry feeds. If you are a breeder, deficiency of this vitamin causes embryo death during the early stages of incubation. This important vitamin is found in dairy products, yeast, liver, and plenty of leafy green vegetables.
Vitamin E. 3. Needed for proper health and protection from diseases, vitamin E is found in fresh greens, wheat germ oil, and whole grains (such as oats, corn, wheat, barley, etc.)
As you can see, the majority of the vitamins needed by chickens are found in sunlight and fresh greens. This is why free ranged chickens (or chickens in confined-free-range-systems) are so healthy. Plenty of clean air, fresh food, sunlight, and green veggies along with a few choice supplements should keep your chickens living as long as Methuselah!
poultryOne.com
11/6/09
Porcine Microsomal Vitamin D3 25-Hydroxylase (CYP2D25)
Abstract
The metabolic activation of the prohormone vitamin D3 requires a 25-hydroxylation that has been reported to be catalyzed by both mitochondrial CYP27A and a microsomal vitamin D3 25-hydroxylase in the liver. CYP27A has been extensively studied, but its role as a physiologically important vitamin D3 25-hydroxylase has been questioned. The present paper reports that the microsomal vitamin D325-hydroxylase, purified from pig liver, converted vitamin D3 into 25-hydroxyvitamin D3 in substrate concentrations which are within the physiological range (apparentK m = 0.1 μm). The enzyme 25-hydroxylated vitamin D3, 1α-hydroxyvitamin D3 and vitamin D2 and also converted tolterodine, a substrate for human CYP2D6, into its 5-hydroxymethyl metabolite. Tolterodine inhibited the microsomal 25-hydroxylation, whereas quinidine, an inhibitor of CYP2D6, did not markedly inhibit the reaction. The primary structure of the microsomal vitamin D3 25-hydroxylase, designated CYP2D25, shows 77% identity with that of human CYP2D6. Northern blot and reverse transcription-polymerase chain reaction experiments revealed that CYP2D25 mRNA is expressed in higher levels in liver than in kidney and in small amounts in adrenals, brain, heart, intestine, lung, muscle, spleen, and thymus. Experiments with human liver microsomes and recombinantly expressed CYP2D6 strongly indicate that the microsomal 25-hydroxylation of vitamin D3 in human liver is catalyzed by an enzyme different from CYP2D6.
Fardin Hosseinpour‡ and Kjell Wikvall
The metabolic activation of the prohormone vitamin D3 requires a 25-hydroxylation that has been reported to be catalyzed by both mitochondrial CYP27A and a microsomal vitamin D3 25-hydroxylase in the liver. CYP27A has been extensively studied, but its role as a physiologically important vitamin D3 25-hydroxylase has been questioned. The present paper reports that the microsomal vitamin D325-hydroxylase, purified from pig liver, converted vitamin D3 into 25-hydroxyvitamin D3 in substrate concentrations which are within the physiological range (apparentK m = 0.1 μm). The enzyme 25-hydroxylated vitamin D3, 1α-hydroxyvitamin D3 and vitamin D2 and also converted tolterodine, a substrate for human CYP2D6, into its 5-hydroxymethyl metabolite. Tolterodine inhibited the microsomal 25-hydroxylation, whereas quinidine, an inhibitor of CYP2D6, did not markedly inhibit the reaction. The primary structure of the microsomal vitamin D3 25-hydroxylase, designated CYP2D25, shows 77% identity with that of human CYP2D6. Northern blot and reverse transcription-polymerase chain reaction experiments revealed that CYP2D25 mRNA is expressed in higher levels in liver than in kidney and in small amounts in adrenals, brain, heart, intestine, lung, muscle, spleen, and thymus. Experiments with human liver microsomes and recombinantly expressed CYP2D6 strongly indicate that the microsomal 25-hydroxylation of vitamin D3 in human liver is catalyzed by an enzyme different from CYP2D6.
Fardin Hosseinpour‡ and Kjell Wikvall
11/5/09
Supplements and vitamins: the benefits and dangers of vitamin e
Whether you take it for your skin, your heart, or other health reasons, learn how and when to take Vitamin E... and when not to.
Vitamin E is a useful antioxidant taken internally, usually as a capsule, or used topically as an oil or skin cream. But, while some consider it a "wonder drug," there are clear risks related to this important and versatile vitamin.
First, it's important to understand how Vitamin E earned its title of "Chief Executive Antioxidant" as the famous Dr. Atkins called it.
Antioxidants are like your body's truant officers. They find free radicals--delinquent oxygen molecules in your body that can kill cells, harm your body's DNA, and impair your immune system--and prevent those free radicals from causing further damage.
Free radicals are sometimes created internally, as part of your immune system. But, we also acquire free radicals from outside sources such as tobacco smoke, pollution, food additives, and radiation. Once free radicals are turned loose in your body, they can work with fat and create more free radicals, in a domino effect.
Antioxidants--including Vitamins E, C, and beta-carotene, as well as the mineral selenium--can halt this effect, and the damage caused by excess free radicals.
Free radicals are strongly suspected of causing cancer
and degenerative aging, among other problems. So, it's important to limit free radical damage as much as you can. Vitamin E is one of the dietary leaders in this fight.
Vitamin E is vital for the health of your body's cells, and was once readily available from foods in everyday diets. These include fresh vegetable oils, dark green leafy vegetables, legumes, nuts and seeds, and whole grains.
Today, Vitamin E is often missing from processed foods, where air and heat can damage any Vitamin E content. For example, processing removes 40 - 90% of the Vitamin E in wheat, when producing breakfast cereals and even commercial whole wheat bread.
How much should you take? In 2000, the National Academy of Sciences set Recommended Dietary Allowances (RDAs) of 15 milligrams of Vitamin E daily for healthy men and women over age 18. This is far lower than the dosage in most vitamin capsules, so you may want to consider adding Vitamin E to your diet, by changing what you eat.
FOOD SOURCES OF VITAMIN E
Food sources are always the best, first choice for vitamins. However, to get 15 milligrams of Vitamin E in your diet, you would need to eat five cups of boiled mustard greens, boiled chard, or cooked turnip greens, and they would have to be prepared fresh--not from cans or your grocer's freezer section. At the very least, you'd need 1/4 cup of freshly harvested, dried sunflower seeds.
The incentive for finding your Vitamin E in food sources is two-fold: There are no documented cases of Vitamin E toxicity when the source was fresh food. And, medical science is steadily learning more about micronutrients in vitamins from food sources, so you may get more benefits from them than the pill or capsule versions.
In reality, few people have the time, resources, or palate for large amounts of freshly cooked greens. So, vitamin supplements become important.
VITAMIN SUPPLEMENTS
Vitamin E is readily available in most multivitamins, and as single vitamins--usually capsules--from the grocery store. However, you should still read the labels carefully, to be sure that you're getting the right amount and quality of Vitamin E.
Vitamin E usually comes in a capsule as oil, and should be taken with a meal that includes a small amount of fat. However, since rancid oils are a leading source of dietary free radicals, be sure that your Vitamin E capsules are as fresh as possible. If the package doesn't have a date indicating its shelf life, don't buy it.
Vitamin E is also available as a tablet that is water-soluble. This may be easier for your body to absorb, and is generally preferred for the treatment of joint inflammation and infections.
Finally, there are skin creams and body oils made with Vitamin E, often recommended for burns and stretch marks. Because this vitamin is not generally absorbed through the skin, topical Vitamin E--except by prescription--is usually considered a cosmetic product, not part of your daily vitamin intake.
HOW MUCH TO TAKE
Your first concern is the dosage. You should consult your physician before making any significant dietary or food supplement changes, especially if you are coping with health issues. This is especially true of Vitamin E, since it can be toxic at higher doses.
Most books and articles about Vitamin E recommend starting at a low dose, no greater than 100 IUs, and very slowly increasing to a daily dose of about 400 IUs.
Some health concerns may suggest eventual higher doses. For example, a 1996 article in the medical journal, "Lancet," found that dosages of 400 - 800 IU reduced heart attacks by 77 percent, in over 2000 patients with heart disease. (Stephens, N., et al., Lancet, 1996; 347:781-86.)
However, it is vital not to self-medicate with Vitamin E. There are some significant health risks with this vitamin.
HEALTH RISKS AND VITAMIN E
There are many reasons not to take Vitamin E, and especially not to take it in supplement form at doses higher than the recommended allowance. If you have (or may have) diabetes, rheumatic heart disease, high blood pressure, or a hypothyroid condition (overactive thyroid), check with your doctor before adding any Vitamin E to your diet.
If you take any anticoagulant (anti-clotting) medication or if you take digitalis, don't take Vitamin E without asking your doctor first. If you have vision problems, especially blurry vision, ask your physician before increasing your Vitamin E intake. And, if you are a woman going through menopause and your menses resume after taking Vitamin E, stop taking this vitamin and check with your doctor immediately.
Vitamin E can prevent clotting, so you should discontinue your daily dose of this vitamin before any surgery.
And, there are medications that can interfere with the absorption of Vitamin E. These include anticonvulsive drugs such as Dilantin, and several cholesterol-lowering drugs.
While most people no longer use mineral oil, an old-time laxative and skin lubricant, it also causes problems with vitamin absorption, especially Vitamin E.
THE EXTENDED VITAMIN E FAMILY
In recent years, studies of Vitamin E have revealed several related nutrients, and the importance of using natural forms of the vitamin.
In the past, and for short-term therapeutic use, many relied upon synthetic forms of Vitamin E, usually called "l-alpha tocopherol" on the label.
However, we now know that the natural form of Vitamin E, d-alpha tocopherol (or d-alpha tocopheryl acetate), may be the tip of the iceberg. For full benefits from this important vitamin, check the food supplement label for the full family of Vitamin E, including tocopherol and tocotrienol. Some manufacturers have simplified their labels, and simply refer to these forms as "mixed tocopherols" or "mixed tocotrienols."
Studies are still unclear about the precise benefits of the full range of Vitamin E nutrients, but if your doctor recommends Vitamin E, it's wise to include all forms of the vitamin.
Because there are health risks connected with Vitamin E, it's smart to consult your doctor before taking this vitamin in food supplement form. Your doctor can also recommend the correct dosage for your body, as well as additional reading to learn more about the risks and benefits of Vitamin E supplements.
Articles � Free Online Articles on Health, Science, Education
Vitamin E is a useful antioxidant taken internally, usually as a capsule, or used topically as an oil or skin cream. But, while some consider it a "wonder drug," there are clear risks related to this important and versatile vitamin.
First, it's important to understand how Vitamin E earned its title of "Chief Executive Antioxidant" as the famous Dr. Atkins called it.
Antioxidants are like your body's truant officers. They find free radicals--delinquent oxygen molecules in your body that can kill cells, harm your body's DNA, and impair your immune system--and prevent those free radicals from causing further damage.
Free radicals are sometimes created internally, as part of your immune system. But, we also acquire free radicals from outside sources such as tobacco smoke, pollution, food additives, and radiation. Once free radicals are turned loose in your body, they can work with fat and create more free radicals, in a domino effect.
Antioxidants--including Vitamins E, C, and beta-carotene, as well as the mineral selenium--can halt this effect, and the damage caused by excess free radicals.
Free radicals are strongly suspected of causing cancer
and degenerative aging, among other problems. So, it's important to limit free radical damage as much as you can. Vitamin E is one of the dietary leaders in this fight.
Vitamin E is vital for the health of your body's cells, and was once readily available from foods in everyday diets. These include fresh vegetable oils, dark green leafy vegetables, legumes, nuts and seeds, and whole grains.
Today, Vitamin E is often missing from processed foods, where air and heat can damage any Vitamin E content. For example, processing removes 40 - 90% of the Vitamin E in wheat, when producing breakfast cereals and even commercial whole wheat bread.
How much should you take? In 2000, the National Academy of Sciences set Recommended Dietary Allowances (RDAs) of 15 milligrams of Vitamin E daily for healthy men and women over age 18. This is far lower than the dosage in most vitamin capsules, so you may want to consider adding Vitamin E to your diet, by changing what you eat.
FOOD SOURCES OF VITAMIN E
Food sources are always the best, first choice for vitamins. However, to get 15 milligrams of Vitamin E in your diet, you would need to eat five cups of boiled mustard greens, boiled chard, or cooked turnip greens, and they would have to be prepared fresh--not from cans or your grocer's freezer section. At the very least, you'd need 1/4 cup of freshly harvested, dried sunflower seeds.
The incentive for finding your Vitamin E in food sources is two-fold: There are no documented cases of Vitamin E toxicity when the source was fresh food. And, medical science is steadily learning more about micronutrients in vitamins from food sources, so you may get more benefits from them than the pill or capsule versions.
In reality, few people have the time, resources, or palate for large amounts of freshly cooked greens. So, vitamin supplements become important.
VITAMIN SUPPLEMENTS
Vitamin E is readily available in most multivitamins, and as single vitamins--usually capsules--from the grocery store. However, you should still read the labels carefully, to be sure that you're getting the right amount and quality of Vitamin E.
Vitamin E usually comes in a capsule as oil, and should be taken with a meal that includes a small amount of fat. However, since rancid oils are a leading source of dietary free radicals, be sure that your Vitamin E capsules are as fresh as possible. If the package doesn't have a date indicating its shelf life, don't buy it.
Vitamin E is also available as a tablet that is water-soluble. This may be easier for your body to absorb, and is generally preferred for the treatment of joint inflammation and infections.
Finally, there are skin creams and body oils made with Vitamin E, often recommended for burns and stretch marks. Because this vitamin is not generally absorbed through the skin, topical Vitamin E--except by prescription--is usually considered a cosmetic product, not part of your daily vitamin intake.
HOW MUCH TO TAKE
Your first concern is the dosage. You should consult your physician before making any significant dietary or food supplement changes, especially if you are coping with health issues. This is especially true of Vitamin E, since it can be toxic at higher doses.
Most books and articles about Vitamin E recommend starting at a low dose, no greater than 100 IUs, and very slowly increasing to a daily dose of about 400 IUs.
Some health concerns may suggest eventual higher doses. For example, a 1996 article in the medical journal, "Lancet," found that dosages of 400 - 800 IU reduced heart attacks by 77 percent, in over 2000 patients with heart disease. (Stephens, N., et al., Lancet, 1996; 347:781-86.)
However, it is vital not to self-medicate with Vitamin E. There are some significant health risks with this vitamin.
HEALTH RISKS AND VITAMIN E
There are many reasons not to take Vitamin E, and especially not to take it in supplement form at doses higher than the recommended allowance. If you have (or may have) diabetes, rheumatic heart disease, high blood pressure, or a hypothyroid condition (overactive thyroid), check with your doctor before adding any Vitamin E to your diet.
If you take any anticoagulant (anti-clotting) medication or if you take digitalis, don't take Vitamin E without asking your doctor first. If you have vision problems, especially blurry vision, ask your physician before increasing your Vitamin E intake. And, if you are a woman going through menopause and your menses resume after taking Vitamin E, stop taking this vitamin and check with your doctor immediately.
Vitamin E can prevent clotting, so you should discontinue your daily dose of this vitamin before any surgery.
And, there are medications that can interfere with the absorption of Vitamin E. These include anticonvulsive drugs such as Dilantin, and several cholesterol-lowering drugs.
While most people no longer use mineral oil, an old-time laxative and skin lubricant, it also causes problems with vitamin absorption, especially Vitamin E.
THE EXTENDED VITAMIN E FAMILY
In recent years, studies of Vitamin E have revealed several related nutrients, and the importance of using natural forms of the vitamin.
In the past, and for short-term therapeutic use, many relied upon synthetic forms of Vitamin E, usually called "l-alpha tocopherol" on the label.
However, we now know that the natural form of Vitamin E, d-alpha tocopherol (or d-alpha tocopheryl acetate), may be the tip of the iceberg. For full benefits from this important vitamin, check the food supplement label for the full family of Vitamin E, including tocopherol and tocotrienol. Some manufacturers have simplified their labels, and simply refer to these forms as "mixed tocopherols" or "mixed tocotrienols."
Studies are still unclear about the precise benefits of the full range of Vitamin E nutrients, but if your doctor recommends Vitamin E, it's wise to include all forms of the vitamin.
Because there are health risks connected with Vitamin E, it's smart to consult your doctor before taking this vitamin in food supplement form. Your doctor can also recommend the correct dosage for your body, as well as additional reading to learn more about the risks and benefits of Vitamin E supplements.
Articles � Free Online Articles on Health, Science, Education
High Prevalence of Vitamin D Inadequacy and Implications for Health
During the past decade, major advances have been made in vitamin D research that transcend the simple concept that vitamin D is important for the prevention of rickets in children and has little physiologic relevance for adults. Inadequate vitamin D, in addition to causing rickets, prevents children from attaining their genetically programmed peak bone mass, contributes to and exacerbates osteoporosis in adults, and causes the often painful bone disease osteomalacia. Adequate vitamin D is also important for proper muscle functioning, and controversial evidence suggests it may help prevent type 1 diabetes mellitus, hypertension, and many common cancers. Vitamin D inadequacy has been reported in approximately 36% of otherwise healthy young adults and up to 57% of general medicine inpatients in the United States and in even higher percentages in Europe. Recent epidemiological data document the high prevalence of vitamin D inadequacy among elderly patients and especially among patients with osteoporosis. Factors such as low sunlight exposure, age-related decreases in cutaneous synthesis, and diets low in vitamin D contribute to the high prevalence of vitamin D inadequacy. Vitamin D production from cutaneous synthesis or intake from the few vitamin D-rich or enriched foods typically occurs only intermittently. Supplemental doses of vitamin D and sensible sun exposure could prevent deficiency in most of the general population. The purposes of this article are to examine the prevalence of vitamin D inadequacy and to review the potential implications for skeletal and extraskeletal health.
Michael F. Holick, PhD, MD
Michael F. Holick, PhD, MD
11/4/09
Vitamin B12: The Ultimate Nutrition Supplement
Some of the vitamins found are anti-acne vitamins, detoxifying vitamins, vitamins to improve digestion, anti aging vitamins, vitamins for improving blood pressure and much more like all this. But the Ultimate nutrition supplement which probably everyone mainly overlooks is Vitamin B12.
But why is Vitamin B12 considered so much important? It is just because it is considered to be an essential supplement for overall health of an individual. It has various types of uses. It helps the body in conversion of sugar, proteins and carbohydrates into energy which further prevents the body in avoiding the feeling of getting tired which a normal person feels in its daily routine. Next the red blood cells formation is also promoted by this supplement. Also it helps the white blood cells in keeping the working of the body’s immune system in perfect shape. It acts as a preservative of fatty layer for nerve cells and along with this regeneration of cells is promoted.
This vitamin is so much important in the body because if this vitamin lacks in the body it would lead to quite serious outcomes like numbness in feet and hands, fatigue and shortness of breath. The more deficiency of this only vitamin can lead to evolvement of pernicious anemia. The reduced level of this vitamin inside the body would be a cause of usage to certain medications for fighting gastric conditions or any surgery for digestive purposes.
This vitamin is normally discovered in dairy products, poultry, red meats and seafood. The foods like mussels
, beef liver and clams contains highest amount of vitamin B12. Overcooking of these foods would lead to loss of these important nutrients from itself. An active formulation of vitamin B12 is known as Methylcobalamin.
The steadiest formulation of the vitamin B12 is cyanocobalamin. As it is very much easy in combining and crystallizing it is found usually in multi-vitamins. Be it the most common one but still it is not able to fulfill the requirements and provide with right amount of it to the body. In the digestive process the effectiveness of itself is lost. It means one might not be able to get the proper dosage as it was claimed on the box.
Ricky Hussey
October 27, 2009
But why is Vitamin B12 considered so much important? It is just because it is considered to be an essential supplement for overall health of an individual. It has various types of uses. It helps the body in conversion of sugar, proteins and carbohydrates into energy which further prevents the body in avoiding the feeling of getting tired which a normal person feels in its daily routine. Next the red blood cells formation is also promoted by this supplement. Also it helps the white blood cells in keeping the working of the body’s immune system in perfect shape. It acts as a preservative of fatty layer for nerve cells and along with this regeneration of cells is promoted.
This vitamin is so much important in the body because if this vitamin lacks in the body it would lead to quite serious outcomes like numbness in feet and hands, fatigue and shortness of breath. The more deficiency of this only vitamin can lead to evolvement of pernicious anemia. The reduced level of this vitamin inside the body would be a cause of usage to certain medications for fighting gastric conditions or any surgery for digestive purposes.
This vitamin is normally discovered in dairy products, poultry, red meats and seafood. The foods like mussels
, beef liver and clams contains highest amount of vitamin B12. Overcooking of these foods would lead to loss of these important nutrients from itself. An active formulation of vitamin B12 is known as Methylcobalamin.The steadiest formulation of the vitamin B12 is cyanocobalamin. As it is very much easy in combining and crystallizing it is found usually in multi-vitamins. Be it the most common one but still it is not able to fulfill the requirements and provide with right amount of it to the body. In the digestive process the effectiveness of itself is lost. It means one might not be able to get the proper dosage as it was claimed on the box.
Ricky Hussey
October 27, 2009
VITAMIN
group of organic substances that are required in the diet of humans and animals for normal growth, maintenance of life, and normal reproduction. Vitamins act as catalysts; very often either the vitamins themselves are coenzymes, or they form integral parts of coenzymes. A substance that functions as a vitamin for one species does not necessarily function as a vitamin for another species. The vitamins differ in structure, and there is no chemical grouping common to them all.
They were first called accessory factors because in 1906 it was found by English biochemist Sir F. G. Hopkins that most foods contain—besides carbohydrates, proteins, fats, minerals, and water—other substances necessary for health. The word vitamin was derived from the term vitamine, used by Polish-American biochemist Casimir Funk to describe an amine (organic base) that was essential to life (it was later found to be thiamine). In 1912 Hopkins and Funk formulated the vitamin hypothesis of deficiency disease; that is, that certain diseases are caused by a dietary lack of specific vitamins.
The chemical structures of the vitamins are all known, and all of them have been synthesized; the vitamins in foods are identical to the synthetic ones. A well-balanced diet usually satisfies the minimum vitamin requirements of human beings. The Recommended Dietary Allowance (RDA) of each vitamin is the standard guideline put forward by the Food and Nutrition Board, National Academy of Sciences–National Research Council. It is based on the nutritional needs of an average, healthy person. Different amounts may be recommended for children, older people, lactating mothers, or people dealing with an ongoing disease process. The U.S. RDA was the federal government's interpretation of the National Research Council's RDA. Since mid-1994, the U.S. RDA has been replaced on food labels by a Percent Daily Value (the percentage of the U.S. RDA that the labeled food offers). Listings for vitamins A and C are required; others are optional.
The amount of each vitamin that should be consumed for optimal health and the wisdom of taking vitamin supplements, especially in "megadoses," is a controversial question. The Dietary Supplement Health and Education Act of 1994 defined vitamins as dietary supplements (rather than drugs) and shifted the burden of proof of safety from the manufacturers to the Food and Drug Administration. Although vitamins were previously seen only as preventives against the various deficiency diseases, more and more studies have examined additional health benefits of vitamins. Health claims that are unsubstantiated by scientific study, however, are regarded by many health and nutrition experts as fraudulent or dangerous, and many physicians now question the need for healthy persons to take multivitamin supplements, because many foods, such as milk and bread, are fortified with vitamins.
Vitamins were originally classified according to their solubility in water or fats, and as more and more were discovered they were also classified alphabetically. The fat-soluble vitamins are A, D, E, and K; the B complex and C vitamins are water soluble. A group of substances that decrease blood capillary fragility, called the vitamin P group, are no longer considered to be vitamins.
Vitamin A
Vitamin A (retinol), a fat-soluble lipid, is either derived directly from animal foods such as liver, egg yolks, cream, or butter or is derived from beta-carotene, a pigment that occurs in leafy green vegetables and in yellow fruits and vegetables. Vitamin A is essential to skeletal growth, normal reproductive function, and the health of the skin and mucous membranes. One form, retinal, is a component of visual purple, a photoreceptor pigment in the retina of the eye (see vision). In addition, beta-carotene, like other carotenoids, is now recognized as an important antioxidant.
A deficiency of vitamin A can cause retarded skeletal growth, night blindness, various abnormalities of the skin and linings of the genitourinary system and gastrointestinal tract, and, in children, susceptibility to serious infection. The eye disorders that result from a deficiency of vitamin A can lead to permanent blindness. Severe deficiency can cause death. As with the other fat-soluble vitamins, conditions that lead to an inability to absorb fats, such as obstruction of bile flow or excessive use of mineral oil, can produce a deficiency state. Overconsumption of vitamin A can cause irritability, painful joints, growth retardation, liver and spleen enlargement, hair loss, and birth defects. The National Research Council recommended daily dietary allowance for adults is 1,000 micrograms (retinol equivalents) for men and 800 micrograms for women.
Vitamin B Complex
Commonly grouped as the vitamin B complex are eight water-soluble vitamins.
Thiamine
Thiamine (vitamin B1 or antiberiberi factor) is a necessary ingredient for the biosynthesis of the coenzyme thiamine pyrophosphate; in this latter form it plays an important role in carbohydrate metabolism. Good sources are yeast, whole grains, lean pork, nuts, legumes, and thiamine-enriched cereal products. This vitamin is a factor in the maintenance of appetite, normal intestinal function, and in the health of the cardiovascular and nervous systems. A deficiency of the vitamin may lead to beriberi; the disease was first shown to result from a dietary deficiency by Dutch physician Christiaan Eijkman. The recommended dietary allowance for adults is 1.2 to 1.4 mg for men and 1.0 to 1.1 mg for women.
Riboflavin
Riboflavin (vitamin B2 or lactoflavin) is used to synthesize two coenzymes that are associated with several of the respiratory enzymes of plants and animals (including humans) and is therefore important in biochemical oxidations and reductions. Deficiency leads to fissures in the corners of the mouth, inflammation of the tongue showing a reddish purple coloration, skin disease, and often severe irritation of the eyes. The recommended dietary allowance for adults is 1.4 to 1.7 mg for men and 1.2 to 1.3 mg for women. Riboflavin is widely distributed in plant and animal tissues; milk, organ meats, and enriched cereal products are good sources.
Niacin
The B vitamins niacin (nicotinic acid) and niacinamide (nicotinamide) are commonly known as preventives of pellagra, which in 1912 was shown by American medical researcher Joseph Goldberger to result from a dietary deficiency. Niacin was first synthesized in 1867. The amino acid tryptophan is the precursor of niacin. Niacin and niacinamide function in the biochemistry of humans and other organisms as components of the two coenzymes nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP); these operate in many enzyme-catalyzed oxidation and reduction reactions. The deficiency state in humans causes skin disease, diarrhea, dementia, and ultimately death. The deficiency state in dogs analogous to pellagra in humans is called blacktongue disease. Lean meats, peanuts and other legumes, and whole-grain or enriched bread and cereal products are among the best sources of niacin. The recommended daily dietary allowance for adults is 16 to 19 mg niacin equivalents (60 mg of dietary tryptophan to 1 mg of niacin) for men and 13 to 14 mg for women.
Vitamin B6 Group
Pyridoxine, pyridoxal, and pyridoxamine make up the vitamin B6 group. They all combine with phosphorus in the body to form the coenzyme pyridoxal phosphate, which is necessary in the metabolism of amino acids, glucose, and fatty acids. The best sources of B6 vitamins are liver and other organ meats, corn, whole-grain cereal, and seeds. Deficiency can result in central nervous system disturbances (e.g., convulsions in infants) due to the role of B6 in serotonin and gamma-aminobutyric acid synthesis. More generally the effects of deficiency include inadequate growth or weight loss and anemia due to the role of B6 in the manufacture of hemoglobin. The recommended dietary allowance for adults is 2.0 to 2.2 mg for men and 2 mg for women. Additional doses are required in pregnancy and by those taking oral contraceptives or the tuberculosis drug izoniazid. Severe nerve damage has been reported from megadoses.
Pantothenic Acid
Pantothenic acid, another B vitamin, is present in perhaps all animal and plant tissues, as well as in many microorganisms. Good sources of it include liver, kidney, eggs, and dairy products. It is a component of the important substance coenzyme A, which is involved in the metabolism of many biochemical substances including fatty acids, steroids, phospholipids, heme, amino acids, and carbohydrates. The adrenal gland is an important site of pantothenic acid activity. There is no known naturally occurring deficiency state and no known toxicity to pantothenic acid. The estimated safe and adequate daily intake for adults is 4 to 7 mg.
Biotin
Biotin is a B vitamin that functions as a coenzyme in the metabolism of carbohydrates, fats, and amino acids. Although it is vitally necessary to the body, only exceedingly small quantities are needed, and since biotin is synthesized by intestinal bacteria, naturally occurring biotin deficiency disease is virtually unknown. The disease state can be produced artificially by including large quantities of raw egg white in the diet; the whites contain avidin, a biotin antagonist. Especially good sources of this widely distributed vitamin include egg yolk, kidney, liver, tomatoes, and yeast. There is no known toxicity to biotin. The estimated safe and adequate daily intake for adults is 100 to 200 micrograms.
Folic Acid
Folic acid (pteroylglutamic acid, folacin, or vitamin B9) occurs abundantly in green leafy vegetables, fruits (e.g., apples and oranges), dried beans, avocados, sunflower seeds, and wheat germ. Derivatives of this vitamin are directly involved in the synthesis of nucleic acids; for this reason cells in the body that are subject to rapid synthesis and destruction are especially sensitive to folic acid deprivation. For example, the retarded synthesis of blood cells in folic acid deficiency results in several forms of anemia, while failure to replace rapidly destroyed cells in the intestinal wall results in a disease called sprue. Inadequate amounts of folic acid in the diet of pregnant women have been strongly associated with neural tube defects (i.e., spina bifida and anencephaly) in newborns; fortification of flours, cornmeal, rice, and pasta (in a manner similar to the fortification of milk with vitamin D) has been required in the United States since 1998. Adequate folic acid also reduces the risk of premature birth. A U.S. study published in 1998 involving 80,000 women showed significant reduction of heart disease among those whose diets included adequate amounts of folate and vitamin B6. Several chemical antagonists to the action of folic acid have been developed in the hope that they might inhibit the growth of rapidly dividing cancer cells; one such compound, methotrexate, is used to treat leukemia in children. The recommended daily dietary allowance for adults is 400 micrograms. Para-aminobenzoic acid (PABA), which is incorporated into the folic acid molecule, is sometimes listed separately as a B vitamin, although there is no evidence that it is essential to the diet of humans.
Vitamin B12
The molecular structure of vitamin B12 (cobalamin), the most complex of all known vitamins, was announced in 1955 by several scientists, including British biochemists A. R. Todd and Dorothy Hodgkin. In 1973 the vitamin was reported to have been synthesized by organic chemists. Vitamin B12 and closely related cobalamins are necessary for folic acid to fulfill its role; both are involved in the synthesis of proteins. American physicians G. R. Minot and W. P. Murphy in 1926 fed large amounts of liver to patients with pernicious anemia and cured them; the curative substance in this case was probably vitamin B12. However, pernicious anemia in humans is caused not by a vitamin B12 deficiency in the diet but rather the absence of a substance called the intrinsic factor, ordinarily secreted by the stomach and responsible for facilitating the absorption of B12 from the intestine. When a person's body cannot produce the intrinsic factor, the standard treatment today is to inject vitamin B12 directly into the bloodstream. Minot and Murphy's therapy worked because the liver they fed their patients contained such large quantities of B12 that sufficient amounts of the vitamin were absorbed without the assistance of the intrinsic factor. Inadequate absorption of B12 causes pernicious anemia, nervous system degeneration, and amenorrhea. The only site of cobalamin synthesis in nature appears to be in microorganisms; neither animals nor higher plants are capable of making these vitamin B12 derivatives. Nevertheless, such animal tissues as the liver, kidney, and heart of ruminants contain relatively large quantities of vitamin B12; the vitamin stored in these organs was originally produced by the bacteria in the ruminant gut. Bivalves (clams or oysters), which siphon microorganisms from the sea, are also good sources. Plants, on the other hand, are poor sources of vitamin B12. The recommended daily dietary allowance for adults is 3 micrograms.
Vitamin C
Vitamin C, or ascorbic acid, a water-soluble vitamin, was first isolated (from adrenal cortex, oranges, cabbage, and lemon juice) in the laboratories of American biochemists Albert Szent-Gyorgyi and Charles King in the years 1928–33. Szent-Gyorgyi found the Hungarian red pepper to be an exceptionally rich source; citrus fruits and tomatoes are also excellent sources. Other good sources include berries, fresh green and yellow vegetables, and white potatoes and sweet potatoes. The vitamin is readily oxidized and therefore is easily destroyed in cooking and during storage. All animals except humans, other primates, guinea pigs, and one bat and bird species are able to synthesize ascorbic acid. Ascorbic acid is necessary for the synthesis of the body's cementing substances: bone matrix, collagen, dentin, and cartilage. It is an antioxidant and is necessary to several metabolic processes. Deficiency of vitamin C results in scurvy, the symptoms of which are largely related to inadequate collagen synthesis and defective formation of intercellular materials. Ascorbic acid is metabolized slowly in humans, and symptoms of scurvy are usually not seen for three or four months in the absence of any dietary vitamin C. The use of megadoses of ascorbic acid to prevent common colds, stress, mental illness, cancer, and heart disease is a continuing subject of research. A study conducted in Great Britain in 1998 found that 500 mg of vitamin C daily had pro-oxidant as well as antioxidant effects and could damage DNA, the genetic material. The recommended daily allowance for adults is 60 mg.
Vitamin D
Vitamin D is a name given to two fat-soluble compounds; calciferol (vitamin D2) and cholecalciferol (vitamin D3). They are now known to be hormones, but continue to be grouped with vitamins because of historical misclassification. Vitamin D3 plays an essential role in the metabolism of calcium and phosphorus in the body and prevents rickets in children. A plentiful supply of 7-dehydrocholesterol, the precursor of vitamin D3, exists in human skin and needs only to be activated by a moderate amount of ultraviolet light (less than a half hour of sunlight) to become fully potent. Rickets is usually caused by a lack of exposure to sunlight rather than a dietary deficiency, although dietary deficiencies can result from malabsorption in the small intestine caused by conditions such as sprue or colitis. Rickets can be prevented and its course halted by the intake of vitamin D2 (found in irradiated yeast and used in some commercial preparations of the vitamin) or vitamin D3 (found in fish liver oils and in fortified milk). Symptoms of vitamin D deficiency in children include bowlegs, knock knees, and more severe (often crippling) deformations of the bones. In adults deficiency results in osteomalacia, characterized by a softening of the bones. Excessive vitamin D consumption can result in toxicity. Symptoms include nausea, loss of appetite, kidney damage, and deposits of insoluble calcium salts in certain tissues. The recommended daily dietary allowance for cholecalciferol is 5 to 10 micrograms (200 to 400 IU) depending upon age and the availability of sunlight. Fortified cow's milk supplies 400 IU per quart (422 IU per liter).
Vitamin E
Vitamin E occurs in at least eight molecular forms (tocopherols or tocotrienols); in humans the most biologically active form has generally been considered to be alpha-tocopherol, which is also the most common. All forms exist as light yellow, viscous oils. The best sources are vegetable oils. Other sources include green leafy vegetables, wheat germ, some nuts, and eggs. Vitamin E is necessary for the maintenance of cell membranes. It is essential to normal reproduction in some animals, but there is no evidence that it plays a role in human reproduction. It is a potent antioxidant; numerous studies have pointed to a protective effect against arterial plaque buildup and cancer. It is helpful in the relief of intermittent claudication (calf pain) and in preventing problems peculiar to premature infants. In large doses, it has an anticoagulant effect. The recommended daily dietary allowance for adults is 10 mg (tocopherol equivalents) for men and 8 mg for women, but nutritionists and physicians sometimes recommend higher doses for disease prevention.
Vitamin K
Vitamin K consists of substances that are essential for the clotting of blood. It was identified in 1934 by Danish biochemist Henrik Dam. Two types of K vitamins have been isolated: K1, an oil purified from alfalfa concentrates, and K2, synthesized by the normal intestinal bacteria. Both can be derived from the synthetic compound menadione (sometimes called vitamin K3), a yellow crystalline solid that is as potent in its ability to promote blood clotting as the natural vitamins. The best sources are leafy green vegetables, such as cabbage and spinach, and intestinal bacteria (which produce most of the body's supply of vitamin K). Vitamin K is required for the synthesis in the liver of several blood clotting factors, including prothrombin. Coumarin derivatives, used in medicine to prevent blood coagulation in certain cases, act by antagonizing the action of vitamin K. In the deficiency state an abnormal length of time is needed for the blood to clot, and there may be hemorrhaging in various tissues. Deficiency occurs in hemorrhagic disease of the newborn infant, in liver damage, and in cases where the vitamin is not absorbed properly by the intestine. It can also occur in coumarin therapy or when normal intestinal bacteria are destroyed by extended antibiotic therapy. Vitamin K does not treat hemophilia. Deficiency is rarely of dietary origin. The estimated safe and adequate intake for adults is 70 to 140 micrograms.
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