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n.

Any of several fat-soluble vitamins consisting of tocopherols, especially alpha-tocopherol, that are found chiefly in plant leaves, wheat germ oil, and milk and that act as antioxidants in the body.

A group of compounds, α, β, γ, and δ tocopherols, that have a chromanol ring and phytyl side chain and are widely distributed in nature, especially in edible vegetable oils (wheat germ, sunflower, cottonseed, safflower, canola, soybean, and corn oil). Unprocessed grains, nuts, and vegetables are other sources. When used as supplements, there are two vitamin E products available: natural source RRR α-tocopherol and synthetic all-rac-α-tocopherol. The latter is a mixture of eight different stereoisomers, of which only one is RRR α-tocopherol. See also Vitamin.

The terms “vitamin E” and “α-tocopherol” are frequently used interchangeably in human nutrition, but it is imperative to distinguish between supplements of RRR α-tocopherol and of synthetic α-tocopherol because their biological activity is different. Since the major function of vitamin E is to serve as a chain-breaking antioxidant, protecting cell membranes against free-radical damage, the most potent form of the vitamin should be used as a supplement. Although gastrointestinal absorption of all forms of vitamin E is equivalent, the subsequent physiological steps are sharply in favor of the RRR form. This action is mediated by a cellular liver transfer protein that is specific for the RRR form of α-tocopherol. It maintains the plasma level by selectively choosing the RRR form and recycling it into plasma lipoproteins for distribution of the vitamin to every tissue and organ in the body.

When deficiencies of the vitamin occur in humans as a consequence of acquired malabsorption or genetic abnormalities of lipoproteins or of the transfer protein, the major symptoms that develop are in the nervous system. Ataxia (lack of muscular coordination) and other neurologic symptoms result in severe incoordination and subsequent musculoskeletal changes.

The recommended daily allowance for vitamin E is 15 milligrams, which is present in the usual Western diet.

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Generic descriptor for a group of fat-soluble compounds essential for reproduction in animals. Essential for human beings (not for reproduction, so far as is known) but rarely, if ever, deficient in the diet. Two main groups of compounds have vitamin E activity: the tocopherols and the tocotrienols; there are 4 isomers of each: α-, β-, γ, and δ-tocopherols and α-, β-, γ, and δ-tocotrienols, with differing vitamin potencies.

Vitamin E functions primarily as an antioxidant in cell membranes, protecting unsaturated fatty acids from oxidative damage.

The vitamin E content of foods is expressed as mg α-tocopherol equivalent (based on the different potency of the different vitamers). Vegetables, seeds, and most vegetable oils are good sources. In the UK and the EU an adequate intake is 0.4 mg/g dietary polyunsaturated fatty acid intake; the US/Canadian RDA is 15 mg/day. The obsolete international unit of vitamin E activity was equal to 1 mg of synthetic α-tocopherol; on this basis natural-source α-tocopherol is 1.49 iu/mg.

anti-sterility factor; fertility vitamin

A group of related compounds called tocopherols which maintain the integrity of cell membranes. Vitamin E is an antioxidant and mutually protects vitamins A and C. Some coaches claim that it increases muscular development and function; this claim is hotly disputed, but there is considerable support for the suggestion that vitamin E reduces the oxygen requirements of muscles and so enhances performance. It has been suggested that physical endurance at high altitudes may be increased, and oxygen debt reduced, by taking 1200 IU of vitamin E per day. Such high doses can be toxic and should be taken only under medical supervision. Vitamin E is widely available in the diet. The richest sources include wheatgerm oil, sunflower oil, and roasted peanuts. Natural sources of Vitamin E are almost twice as potent as synthetic vitamin E. Natural and synthetic forms can be identified by subtle differences in the names of their main components: natural forms are known as ‘d-alpha tocopherol’ and the synthetic ones as ‘dl-alpha tocopherol’. Vitamin E deficiencies are rare, but when they do occur they may lead to destruction of red blood cells and anaemia. Deficiencies impair the reproductive ability of rats and causes muscle wasting in pigs, but vitamin E has no effect on human fertility or libido. There is a growing body of good evidence that vitamin E supplements may offer some protection against atherosclerosis and heart disease. It has also been suggested that supplements may reduce the risk of miscarriages, but this suggestion is disputed.

n

(tocopherol, tocotrienol antisterility factor), the tocopherol and tocotrienols have varying degrees of vitamin E activity but α-tocopherol is the most active. These fat-soluble compounds are found in eggs, muscle meats, liver, fish, chicken, oatmeal, and the oils of corn, soya, and cottonseed. In rats, the lack of vitamin E leads to fetus resorption in the female and atrophy of spermatogenic tissue with permanent sterility in the male. Vitamin E deficiency in humans is correlated with increased hemolysis of erythrocytes. The tocopherols prevent peroxidation of unsaturated fatty acids, and vitamin E requirements appear to be directly related to the dietary intake of unsaturated fatty acids. Although animals develop symptoms of muscular dystrophy on deficient diets, the vitamin has no effect on the human disease.

Brand names: Aquasol E®

Drug Forms:
• Vitamin E tablets or capsules (below)
• Vitamin E oral solution
• Vitamin E skin cream, ointment, or gel

Español:
• Tabletas o cápsulas de vitamina E
• Solución oral de vitamina E
• Crema, pomada o gel de vitamina E para la piel

Vitamin E tablets or capsules

What are vitamin E tablets or capsules?

ALPHA TOCOPHEROL (Vitamin E) helps protect the cells of your body from damaging chemical reactions, and it is important for the proper functioning of nerves and muscles. Vitamin E is a naturally occurring vitamin that is found in many foods such as cereal grains, fruits, green leafy vegetables, vegetable oils, and wheat germ oil. Vitamin E deficiency is rare because it is stored in body fat. Generic vitamin E tablets and capsules are available.

What should I tell my health care provider before I take this medicine?

They need to know if you have any of the following conditions:
• anemia
• blood clotting problems
• an unusual or allergic reaction to vitamin E, other medicines, foods, dyes, or preservatives

How should I take this medicine?

Take vitamin E tablets or capsules by mouth. Follow the directions on the prescription label. Swallow the tablets or capsules with a drink of water. Swallow capsules whole; do not crush or chew. Some tablets are chewable, read the directions carefully. Take exactly as directed. Do not take more than the recommended daily allowance.

Contact your pediatrician or health care professional regarding the use of this medicine in children. Special care may be needed.

What if I miss a dose?

If you miss a dose, forget it and take the next dose as usual. Do not take double or extra doses. There is no cause for concern if you miss a dose.

What drug(s) may interact with vitamin E?

• mineral oil
• orlistat
• porfimer PDT
• warfarin

Tell your prescriber or health care professional about all other medicines you are taking, including non-prescription medicines, nutritional supplements, or herbal products. Also tell your prescriber or health care professional if you are a frequent user of drinks with caffeine or alcohol, if you smoke, or if you use illegal drugs. These may affect the way your medicine works. Check with your health care professional before stopping or starting any of your medicines.

What should I watch for while taking vitamin E?

Visit your prescriber or health care professional for regular checks on your progress. Taking vitamin E supplements should not be a substitute for a balanced and varied diet. A good diet usually has enough vitamin E for your daily needs. Some foods that contain vitamin E include: cereal grains, fruits, green leafy vegetables, vegetable oils, and wheat germ oil.

What side effects may I notice from taking vitamin E?

The recommended daily allowance of vitamin E does not usually cause any side effects.
Side effects related to overdose include:
• blurred vision
• diarrhea
• dizziness
• headache
• nausea, vomiting
• stomach cramps
• unusual bleeding
• unusual tiredness or weakness

Where can I keep my medicine?

Keep out of the reach of children in a container that small children cannot open.

Store at room temperature between 15 and 30 degrees C (59 and 86 degrees F). Protect from light. Keep container tightly closed. Throw away any unused medicine after the expiration date.

Last updated: 7/1/2002

Important Disclaimer: The drug information provided here is for educational purposes only. It is intended to supplement, not substitute for, the diagnosis, treatment and advice of a medical professional. This drug information does not cover all possible uses, precautions, side effects and interactions. It should not be construed to indicate that this or any drug is safe for you. Consult your medical professional for guidance before using any prescription or over the counter drugs.

Description

Vitamin E is an antioxidant responsible for proper functioning of the immune system and for maintaining healthy eyes and skin. It is actually a group of fat soluble compounds known as tocopherols (i.e., alpha tocopherol and gamma tocopherol). Gamma tocopherol accounts for approximately 75% of dietary vitamin E. Vitamin E rich foods include nuts, cereals, beans, eggs, cold-pressed oils, and assorted fruits and vegetables. Because vitamin E is a fat soluble vitamin, it requires the presence of fat for proper absorption. Daily dietary intake of the recommended daily allowance (RDA) of vitamin E is recommended for optimum health.

Vitamin E is absorbed by the gastrointestinal system and stored in tissues and organs throughout the body. Certain health conditions may cause vitamin E depletion, including liver disease, celiac disease, and cystic fibrosis. Patients with end-stage renal disease (kidney failure) who are undergoing chronic dialysis treatment may be at risk for vitamin E deficiency. These patients frequently receive intravenous infusions of iron supplements, which can act against vitamin E.

Vitamin E deficiency can cause fatigue, concentration problems, weakened immune system, anemia, and low thyroid levels. It may also cause vision problems and irritability. Low serum (or blood) levels of vitamin E have also been linked to major depression.

General Use

Vitamin E is necessary for optimal immune system functioning, healthy eyes, and cell protection throughout the body. It has also been linked to the prevention of a number of diseases. The therapeutic benefits of vitamin E include:

• Cancer prevention and treatment. Vitamin E is a known antioxidant, and has been associated with a reduced risk of gastrointestinal, cervical, prostate, lung, and possibly breast cancer. In addition to its role as a cancer preventive, vitamin E is being studied as a cancer treatment. It has been shown to inhibit the growth of prostate tumors and to induce apoptosis (cell self-destruction) in cancer cells. Vitamin E is also being investigated as an adjunctive treatment for cancer patients undergoing radiation therapy; it is thought that high doses of dietary antioxidants may increase the efficacy of the radiation treatment while protecting healthy cells against damage.
• Immune system protection. Various studies have shown that vitamin E supplementation, particularly in elderly patients, boosts immune system function. Older patients have demonstrated improved immune response, increased resistance to infections, and higher antibody production. Vitamin E has also been used with some success to slow disease progression in HIV-positive patients.
• Eye disease prevention. Clinical studies on vitamin E have shown that supplementation significantly reduces the risk for cataracts and for macular degeneration, particularly among women.

• Memory loss prevention. Vitamin E deficiency has been linked to poor performance on memory tests in some elderly individuals.
• Alzheimer's disease (AD) treatment. In a study performed at Columbia University, researchers found that Alzheimer's patients who took daily supplements of vitamin E maintained normal functioning longer than patients who took a placebo. In 2002, a group of Dutch epidemiologists reported on a much larger populationbased study conducted in the Netherlands between 1990 and 1993, with follow-up examinations in 1994 and 1999. The study confirmed the findings of the Columbia researchers, that high dietary intake of vitamin E lowers the risk of developing AD.
• Liver disease treatment. Vitamin E may protect the liver against disease.
• Diabetes treatment. Vitamin E may help diabetic patients process insulin more effectively. It has also been found to be effective in the treatment of diabetic neuropathy, a family of nerve disorders caused by diabetes. Vitamin E appears to reduce the symptoms of diabetic neuropathy and to improve the speed of transmission of nerve impulses.
• Pain relief. Vitamin E acts as both an anti-inflammatory and analgesic (or pain reliever). Studies have indicated it may be useful for treatment of arthritis pain in some individuals.
• Parkinson's disease prevention. High doses of vitamin E intake was associated with a lowered risk of developing Parkinson's disease in one 1997 Dutch study.
• Tardive dyskinesia treatment. Individuals who take neuroleptic drugs for schizophrenia or other disorders may suffer from a side effect known as tardive dyskinesia, in which they experience involuntary muscle contractions or twitches. Vitamin E supplementation may lessen or eliminate this side effect in some individuals.
• Porphyria treatment. Vitamin E has been found to be beneficial in treating patients with porphyria, a group of disorders characterized by abnormalities in the metabolism of blood pigments, by lowering the level of excretion of these blood pigments in the urine.

Other benefits of vitamin E are less clear cut, and have been called into question with conflicting study results or because of a lack of controlled studies to support them. These include:

• Heart disease prevention. A number of epidemiological studies have indicated that vitamin E may prevent heart disease by lowering total blood cholesterol levels and preventing oxidation of LDL cholesterol. However, a large, controlled study known as the Heart Outcomes Prevention Evaluation (HOPE) published in early 2000 indicates that vitamin E does not have any preventative effects against heart disease. The study followed 9,500 individuals who were considered to be at a high risk for heart disease. Half the individuals were randomly chosen to receive vitamin E supplementation, and the other half of the study population received a placebo. After five years, there was no measurable difference in heart attacks and heart disease between the two patient populations. Still, vitamin E may still hold some hope for heart disease prevention. It is possible that a longer-term study beyond the five years of the HOPE study may demonstrate some heart protective benefits of vitamin E consumption. It is also possible that while the high-risk patient population that was used for the HOPE study did not benefit from vitamin E, an average-risk patient population might still benefit from supplementation. It is also possible that vitamin E needs the presence of another vitamin or nutrient substance to protect against heart disease. Further large, controlled, and long-term clinical studies are necessary to answer these questions.
• Skin care. Vitamin E is thought to increase an individual's tolerance to UV rays when taken as a supplement in conjunction with vitamin C. Vitamin E has also been touted as a treatment to promote faster healing of flesh wounds. While its anti-inflammatory and analgesic properties may have some benefits in reducing swelling and relieving discomfort in a wound, some dermatologists dispute the claims of faster healing, and there are no large controlled studies to support this claim.
• Hot flashes. In a small study conducted at the Mayo Clinic, researchers found that breast cancer survivors who suffered from hot flashes experienced a decrease in hot flashes after taking vitamin E supplementation.
• Muscle maintenance and repair. Recent research has demonstrated that the antioxidative properties of vitamin E may prevent damage to tissues caused by heavy endurance exercises. In addition, vitamin E supplementation given prior to surgical procedures on muscle and joint tissues has been shown to limit reperfusion injury (muscle damage that occurs when blood flow is stopped, and then started again to tissues or organs).
• Fertility. Vitamin E has been shown to improve sperm function in animal studies, and may have a similar effect in human males. Further studies are needed to establish the efficacy of vitamin E as a treatment for male infertility; as of 2002, its role in such treatment is still controversial.

Preparations

The U.S. recommended dietary allowance (RDA) of the alpha-tocopherol formulation of vitamin E is as follows:

• men: 10 mg or 15 IU
• women: 8 mg or 12 IU
• pregnant women: 10 mg or 15 IU
• lactating women: 12 mg or 18 IU

In April 2000, the National Academy of Sciences recommended changing the RDA for vitamin E to 22 international units (IUs), with an upper limit (UL), or maximum daily dose, of 1500 IUs. Daily values for the vitamin as recommended by the U.S. Food and Drug Administration, the values listed on food and beverage labeling, remain at 30 IUs for both men and women age four and older.

Many nuts, vegetable-based oils, fruits, and vegetables contain vitamin E. Foods rich in vitamin E include wheat germ oil (26.2 mg/tbsp), wheat germ cereal (19.5 mg/cup), peanuts (6.32 mg/half cup), soybeans (3.19 mg/cup), corn oil (2.87/tbsp), avocado (2.69 mg), and olive oil (1.68 mg/tbsp.). Grapes, peaches, broccoli, Brussels sprouts, eggs, tomatoes, and blackberries are also good sources of vitamin E. Fresh, raw foods contain the highest levels of the vitamin. Both heat and light can reduce vitamin and mineral potency in fresh foods, so overcooking and improper storage should be avoided. Sliced and chopped foods have more of their surface exposed to light, therefore keeping vegetables and fruits whole may also help to maintain full vitamin potency.

For individuals considered at risk for vitamin E deficiency, or those with an inadequate dietary intake, vitamin E supplements are available in a variety of different forms, including pills, capsules, powders, and liquids for oral ingestion. For topical use, vitamin E is available in ointments, creams, lotions, and oils. Vitamin E is also available commercially as one ingredient of a multivitamin formula.

The recommended daily dosage of vitamin E varies by individual need and by the amount of polyunsaturated fats an individual consumes. The more polyunsaturated fats in the diet, the higher the recommended dose of vitamin E, because vitamin E helps to prevent the oxidizing effects of these fats. Because vitamin E is fat soluble, supplements should always be taken with food.

Supplements are also available in either natural or synthetic formulations. Natural forms are extracted from wheat germ oil and other vitamin E food sources, and synthetic forms are extracted from petroleum oils. Natural formulas can be identified by a d prefix on the name of the vitamin (i.e., d-alpha-tocopherol).

Precautions

Overdoses of vitamin E (over 536 mg) can cause nausea, diarrhea, headache, abdominal pain, bleeding, high blood pressure, fatigue, and weakened immune system function.

Patients with rheumatic heart disease, iron deficiency anemia, hypertension, or thyroid dysfunction should consult their healthcare provider before starting vitamin E supplementation, as vitamin E may have a negative impact on these conditions.

Side Effects

Vitamin E is well-tolerated, and side effects are rare. However, in some individuals who are vitamin K deficient, vitamin E may increase the risk for hemorrhage or bleeding. In some cases, side effects may be decreased or eliminated by adjusting the dosage of vitamin E and vitamin K.

Although the reasons are not yet clear, high intake of vitamin E has been associated with a statistically significant increased risk of breast cancer in men.

Vitamin E ointments, oils, or creams may trigger an allergic reaction known as contact dermatitis. Individuals who are considering using topical vitamin E preparations for the first time, or who are switching the type of vitamin E product they use, should perform a skin patch test to check for skin sensitivity to the substance. A small, dime sized drop of the product should be applied to a small patch of skin inside the elbow or wrist. The skin patch should be monitored for 24 hours to ensure no excessive redness, irritation, or rash occurs. If a reaction does occur, it may be in response to other ingredients in the topical preparation, and the test can be repeated with a different vitamin E formulation. Individuals who experience a severe reaction to a skin patch test of vitamin E are advised not to use the product topically. A dermatologist or other healthcare professional may be able to recommend a suitable alternative.

Interactions

Individuals who take anticoagulant (blood thinning) or anticonvulsant medications should consult their healthcare provider before starting vitamin E supplementation. Vitamin E can alter the efficacy of these drugs.

It is important for persons taking supplemental vitamin E to tell their surgeon if they are scheduled for an operation. Vitamin E may interact with some of the medications given prior to or during surgery; it has also been shown to increase bleeding time if the patient is taking such other herbal preparations as feverfew or gingko biloba.

Non-heme, inorganic iron supplements destroy vitamin E, so individuals taking iron supplements should space out their doses (e.g., iron in the morning and vitamin E in the evening).

Large doses of vitamin A can decrease the absorption of vitamin E, so dosage adjustments may be necessary in individuals supplementing with both vitamins.

Alcohol and mineral oil can also reduce vitamin E absorption, and these substances should be avoided if possible in vitamin E deficient individuals.

Resources

Books

Reavley, Nocola. The New Encyclopedia of Vitamins, Minerals, Supplements, and Herbs. New York: M. Evans & Company, 1998.

Periodicals

Bolle, P., M. G. Evandri, and L. Saso. "The Controversial Efficacy of Vitamin E for Human Male Infertility." Contraception 65 (April 2002): 313-315.

Bonner, L. T., and E. R. Peskind. "Pharmacologic Treatments of Dementia." Medical Clinics of North America 86 (May 2002): 657-674.

Collins, S. C., and R. G. Dufresne Jr. "Dietary Supplements in the Setting of Mohs Surgery." Dermatologic Surgery 28 (June 2002): 447-452.

Engelhart, M. J., M. I. Geerlings, A. Ruitenberg, et al. "Dietary Intake of Antioxidants and Risk of Alzheimer's Disease." Journal of the American Medical Association 287 (June 26, 2002): 3261-3263.

Johnson, K. C., S. Pan, and Y. Mao. "Risk Factors for Male Breast Cancer in Canada, 1994-1998." European Journal of Cancer Prevention 11 (June 2002): 253-263.

Pinelli, A., S. Trivulzio, L. Tomasoni, et al. "High-Dose Vitamin E Lowers Urine Porphyrin Levels in Patients Affected by Porphyria Cutanea Tarda." Pharmacological Research 45 (April 2002): 355-359.

Prasad, K. N., W. C. Cole, B. Kumar, and K. Che Prasad. "Pros and Cons of Antioxidant Use During Radiation Therapy." Cancer Treatment Review 28 (April 2002): 79-91.

Sytze Van Dam, P. "Oxidative Stress and Diabetic Neuropathy: Pathophysiological Mechanisms and Treatment Perspectives." Diabetes/Metabolism Research and Reviews 18 (May-June 2002): 176-184.

"Vitamin E: E for Exaggerated?" Harvard Health Letter 25, no. 5 (March 2000):6(3p).

Yu, A., P. Somasundar, A. Balsubramaniam, et al. "Vitamin E and the Y4 Agonist BA-129 Decrease Prostate Cancer Growth and Production of Vascular Endothelial Growth Factor." Journal of Surgical Research 105 (June 1, 2002): 65-68.

Organizations

American Dietetic Association. 216 West Jackson Blvd., Chicago, IL 60606. (312) 899-0040. .

United States Department of Agriculture. Center for Nutrition Policy and Promotion. 1120 20th Street NW, Suite 200, North Lobby, Washington, D.C. 20036. (202) 418-2312. .

United States Food and Drug Administration (FDA). 5600 Fishers Lane, Rockville, MD 20857. (888) 463-6332. .

[Article by: Paula Ford-Martin; Rebecca J. Frey, PhD]

For more information on vitamin E, visit Britannica.com.

anti-sterility factor; fertility vitamin

A group of related compounds called tocopherols, believed to maintain the integrity of cell membranes. Vitamin E is an antioxidant and mutually protects vitamins A and C. It also acts as an anti-blood-clotting agent and has been used in the USA to treat some heart diseases. Some coaches claim that it increases muscular development and function; this claim is hotly disputed, but there is considerable support for the suggestion that vitamin E reduces the oxygen requirements of muscles and so enhances performance. Vitamin E is widely available in the diet. The richest sources include wheatgerm oil, sunflower oil, and roasted peanuts. Natural sources of vitamin E are almost twice as effective as synthetic vitamin F. Natural and synthetic forms can be identified by subtle differences in the names of their main components: natural forms are known as ‘d-alpha tocopherol’ and the synthetic ones as ‘dl-alpha tocopherol’. Deficiencies are rare, but when they do occur they may lead to destruction of red blood cells and anaemia. Deficiencies impair the reproductive ability of rats and cause muscle wasting in pigs. There is no strong evidence that vitamin E supplementation can help infertile human females, but large doses have been used to prevent miscarriages.

Α-tocopherol, one of the three tocopherols found in wheat germ. Acts as an antioxidant in the prevention of enzootic muscle dystrophy, mulberry heart disease, hepatosis dietetica and exudative diathesis and yellow fat disease, and deficiency of the vitamin is a major cause of these diseases.

• v. E-responsive dermatosis — goats on selenium-deficient diets develop alopecia and seborrhea which responds to vitamin E supplementation; similar skin changes occurred in calves fed a milk substitute deficient in vitamin E.