Vitamin E

Paula Ford-Martin

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. Vitamin E is a known antioxidant, and has been associated with a reduced risk of gastrointestinal, cervical, prostate, lung, and possibly breast cancer .
• 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 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.
• Liver disease treatment. Vitamin E may protect the liver against disease.
• Diabetes treatment. Vitamin E may help diabetic patients process insulin more effectively.
• 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.

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 those 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 which 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.

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), soy beans (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.

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.

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.

Key Terms

Antioxidants

Enzymes which bind with free radicals to neutralize their harmful effects.

Contact dermatitis

Inflammation, redness, and irritation of the skin caused by an irritating substance.

Epidemiological study

A study which analyzes health events and trends in particular patient populations.

Free radicals

Reactive molecules created during cell metabolism that can cause tissue and cell damage like that which occurs in aging and with disease processes such as cancer.

Macular degeneration

Degeneration, or breakdown, of the retina that can lead to partial or total blindness.

Non-heme iron

Dietary or supplemental iron that is less efficiently absorbed by the body than heme iron (ferrous iron).

Reperfusion

The reintroduction of blood flow to organs or tissues after blood flow has been stopped for surgical procedures.

Vitamin A

An essential vitamin found in liver, orange and yellow vegetables, milk, and eggs that is critical for proper growth and development.

Vitamin K

A fat-soluble vitamin responsible for blood clotting, bone metabolism, and proper kidney function.

Further Reading

For Your Information

Books

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

Periodicals

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

Organizations

• 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. http://www.usda.gov/cnpp/.

Gale Encyclopedia of Alternative Medicine. Gale Group, 2001.