Vitamins - Introduction

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Highlights	Phytochemicals	Resources
Introduction	Healthy Foods	References
Carotenoids	Dietary Health Benefits

People Who Have Had Gastric Bypass Surgery. Vitamin deficiency is a recognized complication of gastric bypass surgery. Women, African Americans of both sexes, and adults who have had laparoscopic Roux-en-Y bypass surgery are at highest risk. The deficiency is treated with water-soluble vitamin supplements.

Strict Vegetarians. Strict vegetarians need supplements of vitamin B12, unless they get enough of it from fortified cereals and other grain products.

Dieters and Vegetarians. People on weight-reduction diets of fewer than 1,000 calories a day should probably take a multivitamin, and should also check regularly with a physician.

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Vegetarians may need riboflavin, vitamin B12, and vitamin D supplements. Vegans, who do not eat dairy or eggs as well as meat, may be at further risk for vitamin A deficiencies if they do not also eat plenty of dark-colored fruits and vegetables. Those who eat eggs and dairy products need to only watch their iron levels.

Deficiencies in vegetarian children may be particularly harmful. Pregnant and breast-feeding women who are vegetarians must be sure to have sufficient vitamins. Of special note, maternal deficiencies in vitamin B12 may cause delayed growth and neurologic problems in newborns.

Click the icon to see an image of sources for vitamin D.

Older Adults. Deficiencies of vitamins and important minerals have been observed in almost a third of elderly people. Often their dietary habits slip and they fail to eat balanced meals regularly. In addition, older adults are more likely to be taking medications for a variety of conditions. Multiple drug regimens may prevent absorption of some vitamins. Elderly people, particularly if they are not exposed to sunlight, may be deficient in vitamin D. New recommendations from the International Osteoporosis Foundation advise that older adults get 800 to 1,000 IU of vitamin D a day. People who are obese, or who have osteoporosis, limited sun exposure, or poor nutrient absorption may need to increase their intake to as much as 2,000 IU per day. Seniors also may have low levels of important B vitamins. (Older adults showing signs of dementia should be checked for B12 deficiencies, as well as for other disorders that cause mental disturbances.) It should be noted, however, that metabolism slows down as a person ages, and in elderly people it takes the liver longer to eliminate drugs and vitamins from the body. The effect of some vitamin supplements, therefore, may be intensified. Dosage levels of vitamin A, for instance, which might be harmless in a younger adult, could be toxic in an elderly patient.

People Who Avoid Sunlight. People who avoid sunlight or who are housebound, and whose diet is low in foods that contain vitamin D should take supplements. People with darker skin are at higher risk for deficiencies than those with whiter skin. (Note: Vitamin D is toxic in high doses, and no one should exceed the recommended dietary intake of vitamin D except under the direction of a physician.)

Vitamin A and Provitamin A Carotenoids (Beta-Carotene)
Benefits	Essential for growth, bone development, vision, reproduction, and healthy skin.
Recommended dietary allowance (RDA), AI, or dietary reference intake (DRI) (mcg = micrograms, mg = milligrams, IU = international units)	Vitamin A RDA and Upper Limit (when toxicity is a risk) are the following: For children: 1,000 IU ages 1 -3 (upper limit is 2,000 IU); 1,333 IU ages 4 - 8 (upper limit is 3,000 IU); and 2,000 IU for ages 9 - 13 (upper limit is 5,665 IU). For non-pregnant women: 2,333 IU ages 14 through adulthood (upper limit is 9,335 IU for ages 14 - 18 and 10,000 IU for women over 19). For pregnant women: 2,500 IU for pregnant women under 18; 2,565 IU for pregnant women over 19. (Upper limit is 9,335 IU for ages 14 - 18 and 10,000 IU for women over 19. It should be noted that some experts recommend 8,000 IU as the upper limit during pregnancy.) Warning: Use of preformed vitamin A, including the skin acne medication tretinoin (a vitamin A derivative), during pregnancy can cause birth defects. For nursing women: 4,000 IU for nursing mothers under 18; 4,335 IU for nursing mothers over 19 (upper limit is 9,335 IU for ages 14 - 18 and 10,000 IU for women over 19). For men: 3,000 IU ages 14 - 18; 3,000 IU for ages 19 and above (upper limit is 10,000 IU). Note: In determining the daily vitamin A allowance, experts also take note of provitamins, such as beta-carotene, that convert to vitamin A. Some experts recommend 3 - 6 mg of beta-carotene. Vitamin A is now being measured with a new unit called the Retinol Activity Equivalent (RAE). One RAE is equal to 1 mcg retinol, 12 mcg beta-carotene, 24 mcg alpha-carotene, and 24 mcg beta-cryptoxanthin. Retinol is the most active form of vitamin A.
Foods containing the vitamin	Animal products, such as liver, dairy products, eggs, and fish liver oil. Provitamin A carotenoids are also found in dark red, green, and yellow vegetables and fruits. Requires some dietary fat to be absorbed.
Effects of deficiencies	Skin disorders, severe diarrhea, and eye damage. In less developed countries, severe deficiencies cause blindness in 250,000 children each year. Diets low in vitamin A may also increase the risk of developing cancer. Low dietary intake of vitamin A has been associated with impaired lung function in children.
People at risk for deficiencies	Preschool children and any child with inadequate intake of protein, calories, and zinc. Iron deficiency may also impair metabolism of vitamin A. People with asthma. People with serious disorders in the intestine, liver, or pancreas, such as cystic fibrosis, steatorrhea, biliary obstruction, inflammatory bowel disease, cirrhosis, and other conditions. People who have undergone Roux-en-Y gastric bypass surgery. Vegans (vegetarians who do not eat eggs and dairy). Such individuals should be sure to eat plenty of deep-colored fruits and vegetables. People who abuse alcohol. It should be noted, however, that although people with alcoholism may be at risk for vitamin A deficiency, a combination of high-dose vitamin A and alcohol may cause toxic liver damage. Healthy adults usually have a year's store of vitamin A in the liver, so temporary nutritional deficiencies or problems with fat absorption are unlikely to cause serious vitamin A deficiencies.
Toxicities	Even moderately high doses appear to increase the risk of hip fractures. Very toxic when taken in high-dose supplements for long periods of time. Symptoms of overdose include dizziness, nausea, vomiting, headache, skin damage, mental disturbances, and, in women, infrequent periods. Can affect almost every part of the body, including eyes, bones, blood, skin, central nervous system, liver, and genital and urinary tracts. Severe toxicity can cause blindness and may even be life threatening. In children, chronic overdose can cause fluid on the brain, as well as the same complications seen in adults. High consumption of vitamin A may also increase the risk of gastric cancer, osteoporosis, and fractures in both men and women. Pregnant women who take amounts that are not much higher than the RDA levels increase the risk for birth defects in their children. Liver damage can occur in children who take RDA-approved adult levels for long periods of time or in adults who take as little as five times the RDA-approved amount for 7 - 10 years.

B Vitamins, part 1
	B Vitamins: General Information	Vitamin B1 (thiamin)
Benefits	The B vitamins have a wide and varied range of functions in the human body. Most B vitamins are involved in the process of converting blood sugar into energy.	Essential for converting blood sugar into energy and is involved in metabolic activities in nerves, heart, and muscles and in the production of red blood cells.
Recommended dietary allowance (RDA), AI, or dietary reference intake (DRI) (mcg = micrograms, mg = milligrams, IU = international units)		RDA is 0.5 mg/day for children aged 1-3 years, 0.6 mg/day for children aged 4-8, 0.9 mg/day for children aged 9-13, 1.2 for teen boys and men (ages 14 and up), 1 mg/day for girls aged 14-18 years, and 1.1 mg for women aged 18 and older. The RDA for pregnant and nursing women is 1.4 mg/day.
Foods containing the vitamin		Best source is pork and other good sources are dried fortified cereals, oatmeal, corn, nuts, cauliflower, and sunflower seeds. Supplements for people with normal diets and good health are unnecessary.
Effects of deficiencies	Deficiencies are uncommon in the U.S., but when they occur, they usually involve several B vitamins, since many of them come from the same food groups.	Severe vitamin B1 deficiency is known as beriberi. It can cause visual disturbances, paralysis, staggering, loss of sensation in the legs and feet, psychosis, and congestive heart failure.
People at risk for deficiencies	Alcohol interferes with these vitamins, and some of the physical and mental problems that alcoholics experience may be attributed to a deficiency of B vitamins. Elderly people are also at risk for deficiencies because of inadequate diets and potential interference with B-vitamin absorption by medications. Deficiencies can occur in severely malnourished people or in those receiving long-term dialysis or intravenous feeding. Vegetarians may be at risk.	See general vitamin B description.
Toxicities	Because the B vitamins are water-soluble and eliminated in the urine, toxic reactions from taking most of them orally are extremely rare. (Exceptions are niacin and vitamin B6.) It should be noted that substances known as B15 (pangamic acid) and B17 (laetrile) are neither vitamins nor nutrients; both chemicals are highly dangerous and have no proven nutritional or health value.	No toxic effects have been reported from thiamin.

B Vitamins, part 2
	Vitamin B2 (riboflavin)	Vitamin B3 (niacin) also known as nicotinic acid	Vitamin B5 (pantothenic acid)
Benefits	Important in the production of energy.	Helps break down blood sugar for energy. Acts as a vasodilator, widening blood vessels and increasing blood flow. May be prescribed in very high doses for improving cholesterol levels, but medical supervision is recommended.	Important for metabolism of fats, carbohydrates, and proteins, as well as production of steroid hormones and other important chemicals.
Recommended dietary allowance (RDA), AI, or dietary reference intake (DRI) (mcg = micrograms, mg = milligrams, IU = international units)	RDA is O.5 mg/day for children aged 1-3 years, 0.6 mg/day for children aged 4-8, 0.9 mg/day for children aged 9-13, 1.3 for teen boys and men (ages 14 and up), 1 mg/day for girls aged 14-18 years, and 1.1 mg for women aged 18 and older. The RDA for pregnant women is 1.4 mg/day and for nursing women 1.6 mg/day.	RDA is 6 mg/day for children aged 1-3 years, 8 mg/day for children aged 4-8, 12 mg/day for children aged 9-13, 16 mg/day for teen boys and men (ages 14 and up), 14 mg/day for girls and women aged 14 and older. The RDA for pregnant women is 18 mg/day and for nursing women 17 mg/day.	AI is 2 mg/day for children aged 1-3 years, 2 mg/day for children aged 4-8, 4 mg/day for children aged 9-13, and 5 mg/day for teens and adults (ages 14 and up). The AI for pregnant women is 6 mg/day and for nursing women 7 mg/day.
Foods containing the vitamin	Liver, dried fortified cereals, dairy products, fish. Some dark green vegetables. Supplements for people with normal diets and health are unnecessary.	Mackerel, swordfish, chicken, veal, dried fortified cereals, pork, salmon, and beef liver. Supplements are unnecessary in people with normal health and diets.	Whole grains, beans, milk, eggs, and liver. Supplements are unnecessary in people with normal health and diets.
Effects of deficiencies	Deficiencies affect the skin and mucus membranes and can cause cracks on the lips or corners of the mouth, eczema of the face and genitals, a burning sensation on the tongue, and eye irritation. May contribute to anemia when iron levels are low and contribute to elevated levels of homocysteine, a heart risk factor.	Deficiency causes pellagra; symptoms can include eczema, intestinal and stomach distress, depression, headache, thinning of the hair, and excess saliva production.	Deficiency is unlikely except together with other B vitamin deficiencies. Symptoms include abdominal distress, burning sensation in the heels, and sleep problems.
People at risk for deficiencies	See general vitamin B description.	Alcoholics and any malnourished persons.	Alcoholics and any malnourished persons.
Toxicities	No toxic effects have been reported, even from large doses of riboflavin.	Even mildly high doses of niacin can cause hot flushes of the face and shoulders, headaches, itchiness, and stomach problems. Large doses may trigger erectile dysfunction, ulcers, gout, diabetes, and liver damage, which are usually reversed when high doses are discontinued.	Although no toxicity has been reported in humans, high dosages have caused liver damage in rats.

B Vitamins, part 3
	Vitamin B6 (pyridoxine)	Vitamin B12 (cobalamin)
Benefits	Has an effect on over 60 proteins in the body, including proteins that play a role in the nervous system, red and white blood cell production, and heart disease.	Essential for the production of blood cells, manufacturing genetic material, and healthy functioning of the nervous system.
Recommended dietary allowance (RDA), AI, or dietary reference intake (DRI) (mcg = micrograms, mg = milligrams, IU = international units)	RDA is O.5 mg/day for children aged 1-3 years, 0.6 mg/day for children aged 4-8, 1 mg/day for children aged 9-13, 1.3 for teen boys and men ages 14-50, and 1.7 mg/day for men aged 50 and up; 1.2 mg/day for girls aged 14-18 years, 1.3 mg for women aged 18-50, and 1.5 mg/day for women aged 50 and up. The RDA for pregnant women is 1.9 mg/day and for nursing women 2 mg/day.	RDA is 0.9 mcg/day for children aged 1-3 years, 1.2 mcg/day for children aged 4-8, 1.8 mcg/day for children aged 9-13, and 2.4 mcd/day for teens and adults aged 14 and up. The RDA for pregnant women is 2.6 mcg/day and for nursing women 2.8 mcg/day.
Foods containing the vitamin	Meats, oily fish, poultry, whole grains, dried fortified cereals, soybeans, avocados, baked potatoes with skins, watermelon, plantains, bananas, peanuts, and brewer's yeast.	The only natural dietary sources are animal products, including meats, dairy products, eggs, and fish (clams and oily fish are very high in B12). Like other B vitamins, however, B12 is added to commercial dry cereals and fortified grain products.
Effects of deficiencies	Increased levels of homocysteine, associated with heart disease and possibly Alzheimer's disease. Skin problems and nervous system disorders, including impaired memory and concentration. Increased risk for kidney stones. In unborn children, some evidence shows that lack of vitamin B6, in addition to vitamin B12 and folic acid, may be responsible for defects such as cleft lip and palate and spina bifida. Supplementation with these vitamins is advised during pregnancy. Note: People who have been taking more than 50 mg for some time and stop suddenly are at risk for a so-called "rebound deficiency." When people stop taking vitamin B6, they should taper off slowly.	Increased risk of bone fractures. Abnormal gait in the elderly. May cause severe depression, memory loss, instability, disorientation, decreased reflexes, and possibly hearing loss. Children who are deficient may experience growth failure. Deficiencies in pregnant and breast-feeding women may cause neurologic harm in their babies. A genetic defect that causes vitamin B12 deficiencies is responsible for pernicious anemia, a serious disorder that causes rapid heart rate, shortness of breath, dizziness, weakness, and fatigue. It must be treated with injections of vitamin B12 or very high oral doses to prevent neurologic damage.
People at risk for deficiencies	Alcoholics and malnourished people. In rare cases, infants are born unable to metabolize pyridoxine. In such cases, seizures or convulsions can occur and vitamin B6 must be administered.	Alcoholics and any malnourished persons. Evidence suggests deficiencies may be caused by Helicobacter pylori (H. pylori) bacteria (a cause of ulcers). Nearly 30% of patients with inflammatory bowel disease have vitamin B6 deficiency, as well as low levels of iron and vitamin D. People who take the antibiotic isoniazid, the high blood pressure medication hydralazine, and the drug penicillamine are at risk for vitamin B6 deficiency. The elderly, people with Crohn's disease, and those who have undergone ileal and ileocolonic resection may have trouble absorbing natural vitamin B12 and need to take supplements. Studies have found that patients with diabetes who are treated with metformin are at risk for low levels of vitamin B12. Vegetarians are at higher risk for deficiencies.
Toxicities	Very high doses can cause nerve damage, with symptoms of instability and numbness in the feet and hands, which may be permanent in some cases. Of specific concern are possible adverse effects on nerve development in the babies of pregnant women who take large doses, such as for morning sickness.	There is no evidence of toxicity with this vitamin.

B Vitamins, part 4
	Biotin (a B vitamin)	Choline (a B vitamin)	Folate, or Folic Acid, its synthetic form (a B vitamin)
Benefits	Involved in the production of amino acids, proteins and fatty acids.	Essential for fetal brain development and for learning and memory.	Important for many metabolic processes in the body. It is used to manufacture neurotransmitters (chemical messengers in the brain), protect the heart, and synthesize genetic materials (DNA) in the cells. It may also improve blood flow.
Recommended dietary allowance (RDA), AI, or dietary reference intake (DRI) (mcg = micrograms, mg = milligrams, IU = international units)	AI (daily) is 8 mcg in children aged 1-3, 12 mcg in children aged 4-8, 20 mcg for children aged 9-13, 25 mcg for children aged 14-18, and 30 mcg for anyone over 18, including pregnant women. The AI for nursing women is 35 mcg/day.	AI (daily) is 200 mg in children aged 1-3, 250 mg in children aged 4-8, 375 mg for children aged 9-13, 550 mg for boys and men aged 14 years and up, 400 mg for girls aged 14-18, and 425 for women older than 18. The AI for pregnant women is 450 mg/day, and 550 mg/day for nursing women.	Supplements may be folate (natural) or folic acid (synthetic). Folic acid is nearly twice as potent as folate. RDA is 400 mcg folate for ages 14 and up, 600 mcg during pregnancy and 500 mcg while nursing. The DRI for children aged 1-3 is 150 mcg/day, 200 mcg for children aged 4-8, and 300 mcg for children aged 9-13. Women who are planning to become pregnant should take 400 mcg of folic acid before conception, during pregnancy, and while nursing.
Foods containing the vitamin	Dietary sources are eggs, milk, liver, mushrooms, bananas, tomatoes, whole grains, nuts, and brewer's yeast. Also produced by bacteria in the intestines.	Peanuts, eggs, cauliflower, and meats, especially liver.	Avocado, bananas, orange juice, cold cereal, asparagus, green leafy vegetables, dried beans and peas, and yeast. Folic acid supplements are now added to commercial breads and cereals.
Effects of deficiencies	Deficiencies are almost unheard of.	Low levels during pregnancy increase risk of birth defects in newborns.	As with vitamins B6 and B12, deficiencies of folate elevate levels of homocysteine, an amino acid in the body that may increase the risk for heart disease, and possibly Alzheimer's disease. Folic acid supplements lower homocysteine levels, but with little or no impact on the risk of atherosclerotic disease in the heart or in the peripheral arteries and veins. This suggests that homocysteine may be a marker of cardiovascular disease, rather than a cause. However, some evidence suggests that folic acid supplementation in patients with low folic acid levels substantially reduces the risk of a first stroke. Low folic acid levels during pregnancy increase the risk of birth defects in newborns, and folic acid supplementation plays a key role in preventing birth defects. Folic acid deficiencies can also cause depression, megaloblastic anemia, and impairments in concentration, memory, and hearing.
People at risk for deficiencies			Alcoholics, malnourished persons, people with conditions that disrupt the normal functioning of the small intestine, and people taking certain drugs, particularly methotrexate. Other risk factors for deficiency: high-dose aspirin, smoking, treatment for seizures, taking oral contraceptives.
Toxicities		Excessive doses can cause intestinal problems, and there is also some concern that high doses can cause cancer.	Possible connection between folic acid supplements and colorectal, prostate, and breast cancers now under exploration. Some link between high doses and central nervous system disorders, zinc deficiency, and seizures in epileptics. This risk appears to be low, but results indicate that megadoses should be avoided. High amounts may mask symptoms of vitamin B12 deficiencies.

Vitamin C (Ascorbic Acid)
Benefits	Vitamin C is a water-soluble vitamin. It acts as an antioxidant (reduces harm from damaging chemical processes in the body). Essential for the production of collagen, the basic protein in bones, cartilage, tendons, and ligaments. Other possible benefits include protection against bronchoconstriction during exercise in people with asthma. May help boost the immune system, and reduce the long-term risk of dementia.
Recommended dietary allowance (RDA), AI, or dietary reference intake (DRI) (mcg = micrograms, mg = milligrams, IU = international units)	RDA (daily) is 75 mg (women and boys aged 14-18 years) and 90 mg (men 19 and up). (Smokers need an additional 35 mg.) Pregnant women require 85 mg (80 mg if they are 18 or younger). Nursing mothers need 120 mg (115 mg if they are 18 or younger). Children aged 1-3 need 15 mg, and those aged 4-8 require 25 mg.
Foods containing the vitamin	Citrus fruits and juices, papayas, hot chili peppers, bell peppers, broccoli, potatoes, dark leafy greens, kale, red cabbage, cauliflower, cantaloupe, sweet potatoes, and Brussels sprouts. Orange juice is the most important source of vitamin C in the U.S., with frozen juice being the best source of the vitamin.
Effects of deficiencies	Scurvy is the primary deficiency disease. It affects most body tissues, particularly bones, teeth, and blood vessels. Early symptoms include tiredness, weakness, irritability, weight loss, and vague muscle aches. Later symptoms are bleeding gums, wounds that won't heal, rough skin, and wasting away of the muscles. Deficiencies may contribute to periodontal disease and gallstones. Low dietary intake of vitamin C has been associated with impaired lung function in children. Low intake may also increase lead levels in the blood.
People at risk for deficiencies	Clinical deficiency is rare in the U.S., only occasionally occurring in the elderly, alcoholics, cancer patients, and some people on severely limited diets that are low in fresh fruits and vegetables. Surprisingly, however, studies now suggest that as many as 16% of middle-aged Americans are low in vitamin C, with the highest risk in smokers and middle-aged men. High doses of aspirin taken over a long period of time can interfere with vitamin C absorption.
Toxicities	Tolerable upper limit is 2,000 mg/day in adults (the limit is lower in children). High doses may cause headaches and diarrhea. Long-term high doses may increase risk for kidney stones. Ascorbic acid increases iron absorption, so people with blood disorders, such as hemochromatosis, thalassemia, or sideroblastic anemia should avoid high doses. Large doses may also thin blood and interfere with anticoagulant medications, blood tests used in diabetes, and stool tests. Rebound scurvy can occur after abrupt withdrawal from long-term large doses. This rebound effect may be more significant in infants or pregnant women.

Vitamin D
Benefits	Vitamin D is actually a single term for several hormones that are stored mainly in the liver and also in fat and muscle tissue. It is essential for the absorption of calcium into the bone and for normal bone growth.
Recommended dietary allowance (RDA), AI, or dietary reference intake (DRI) (mcg = micrograms, mg = milligrams, IU = international units)	AI (daily) is 200 IU (5 mcg) for children and most adults to age 50, 400 IU (10 mcg) for people between ages 50 and 70, and 600 IU (15 mcg) for people over age 70. New recommendations from the International Osteoporosis Foundation (IOF) recommend that older adults get 800 to 1,000 IU/day. Many experts currently recommend a dose of 2,000 or more IU daily for adults. Breast-fed infants, as well as people who are obese, have osteoporosis, limited sun exposure, poor nutrient absorption, or dark skin should take vitamin D supplements. The maximum tolerated dose after the age of 12 months is 2,000 IU/day (50 mcg/day). In November 2008, the American Academy of Pediatrics recommended that the minimum intake for children and adolescents be changed to 400 IU/day.
How the body gets the vitamin	There are two forms of vitamin D. Vitamin D3 is made in the body from a chemical reaction to the ultraviolet radiation in sunlight. Vitamin D2 is found in a few food sources, including vitamin D-fortified milk, fatty fish, egg yolks, and liver.
Effects of deficiencies	Softening of the bones caused by low levels of calcium and phosphorous (called rickets in children and osteomalacia in adults). Also increases the risk for bone-related knee problems, and hip fractures in postmenopausal women. Associated with a higher risk for prostate cancer and breast cancer. Evidence suggests that vitamin D deficiency may be responsible for poor muscle strength after bone fracture. The deficiency is associated with high blood pressure and diabetes, but it is unknown whether supplementation with vitamin D impacts these diseases. Lower vitamin D levels have been associated with early age-related macular degeneration (AMD). Research has also linked low vitamin D levels wtih a higher risk for cognitive deficits in the elderly.
People at risk for deficiencies	Older people, particularly if they live in the North, who are underexposed to sunlight. Obesity may also increase risk. There is some concern that vitamin D deficiency may be a growing problem in the U.S. among younger adults as sunscreen use becomes widespread. Individuals at highest risk for vitamin D deficiency are those who avoid the midday sun, wear protective clothing, regularly use sunscreen, and have dark skin. Children ages 1 - 11, especially black and Hispanic children, have also been found to have lower-than-optimal blood levels of vitamin D. Exposure to sunlight for about 15 - 20 minutes at mid-morning or mid-afternoon three times a week is recommended for most people who live in temperate climates.
Toxicities	Vitamin D is very toxic in high doses. In infants, daily amounts higher than 1,000 IU can cause mental and growth retardation, kidney failure, and death. In children and adults, daily amounts over 50,000 IU can cause weakness, anorexia, vomiting, diarrhea, and mental changes. Prolonged use of megadoses can cause calcification of soft tissue and life-threatening kidney failure. Low-calcium diets and withdrawal from the vitamin can usually reverse the side effects, except for kidney failure.

Other Vitamins
	Vitamin E (Tocopherol or Tocotrienol)	Vitamin K
Benefits	A fat-soluble antioxidant vitamin that helps prevent cell membrane damage and may inhibit oxidation of LDL cholesterol (a process that increases its harmful effects on arteries). Researchers once thought that vitamin E might protect against cardiovascular disease. This theory has been debunked. However, vitamin E supplementation may reduce the risk of deep vein thrombosis (DVT) in women at risk for, or with a history of, DVT. It also might lower the risk of dementia and Alzheimer's disease over the long term.	The most important function of vitamin K is its role in blood clotting and prevention of bleeding. The vitamin also contributes to maintaining healthy bones and healing fractures. Vitamin K is widely used in Japan to treat osteoporosis, and studies suggest it may be effective in treating rheumatoid arthritis.
Recommended dietary allowance (RDA), AI, or dietary reference intake (DRI) (mcg = micrograms, mg = milligrams, IU = international units)	RDA is 15 mg (22 IU) for all adults, including pregnant women. Nursing mothers need 19 mg (28 IU). (Supplements should be taken along with some oil or fat to be absorbed most efficiently.) Vitamin E is composed of eight compounds (four tocopherols and four tocotrienols). Vitamin E is most often available as supplements of dl alpha tocopherol (a synthetic form). Other vitamin E compounds may prove to be more active than the standard synthetic supplement. They include natural vitamin E, called d-alpha- or RRR-alpha-tocopherol succinate (VES). Other vitamin E compounds of interest are tocotrienol and beta and gamma tocopherol. Supplements that contain a combination of some of these forms may be most beneficial.	AI is 120 mcg/day in men over age 19 and 90 mcg/day in women over age 19, including pregnant and nursing women. The AI for pregnant and nursing girls age 18 and younger is 75 mcg/day. The AI for children aged 1-3 years is 30 mcg/day, for children 4-8 55 mcg/day, for children 9-13 60 mcg/day, and for teens 14-18 75 mcg/day.
Foods containing the vitamin	Vegetable oils (particularly wheat germ oil), sweet potatoes, turnip greens, mangoes, avocados, nuts, sunflower seeds, and soybeans. Tocotrienol (a possibly beneficial form) is found in natural tropical oils. Palm oil sold in the US is refined and does not contain tocotrienol.	Best dietary sources are canola oil, cruciferous vegetables, and soybean oil. Other good sources are beef liver, bran, and olive oil. Also produced by bacteria in the intestines.
Effects of deficiencies	Deficiencies have not been established.	Easy bruising, bleeding. May increase the risk of hip fractures in women.
People at risk for deficiencies	Low-birth-weight infants. People who eat a low-fat diet. People with medical problems such as Crohn's disease, cystic fibrosis, steatorrhea, and liver diseases (such as cirrhosis), which impair fat absorption. People with abetalipoproteinemia, a rare genetic disorder that impairs fat metabolism.	Deficiency may occur in patients who have problems absorbing fats, such as those with cirrhosis, people who are on long-term antibiotic therapy, or those who are taking other medications, including cholestyramine, Dilantin, and phenobarbital. Some evidence suggests that more young people may be deficient than was previously believed.
Toxicities	Upper level recommended is 1,000 IU of alpha tocopherol. Large doses may cause bleeding problems, particularly in people taking anti-clotting medications. Some research now indicates that vitamin E, like other antioxidants, may have pro-oxidant and damaging effects. Although vitamin E is one of the best studied vitamins, research has yielded conflicting results, and definitive conclusions about the benefits and toxicity of vitamin E have not yet been determined. In one major study, there was no significant difference in cancer rates between people who took 400 IU of vitamin E daily and those who did not, although those who took the supplement had a higher risk of heart failure. Additional studies also link high levels of vitamin E with a slightly increased risk of heart failure and death.	Allergic-type responses, including rash and itching, to high doses have been reported. People who are taking Coumadin, an anticoagulant, should not take vitamin K without consulting a physician. Vitamin K deficiency can cause anorexia, lethargy, growth retardation, bone loss, soft tissue calcification, and death.

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Review Date: 10/08/2010
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org).