What is it?
Vitamin E is an antioxidant that protects cell membranes and other fat-soluble parts of the body, such as low-density lipoprotein (LDL; “bad” cholesterol) cholesterol, from damage.
Where is it found?
Wheat germ oil, nuts and seeds, whole grains, egg yolks, and leafy green vegetables all contain vitamin E. Certain vegetable oils should contain significant amounts of vitamin E. However, many of the vegetable oils sold in supermarkets have had the vitamin E removed in processing. The high amounts found in supplements, often 100 to 800 IU per day, are not obtainable from eating food.
Why do athletes use it?*
Some athletes say that vitamin E
- helps boost immunity.
- helps ease muscle cramps.
What do the advocates say?*
Vitamin E is important to athletes because it is an antioxidant and may help to prevent some of the oxidative damage that may occur from exercise. This oxidative damage, caused by free radicals, may interfere with the cells’ ability to function normally and is believed to play a role in many different health conditions, including the aging process, cancer, and heart disease.
Vitamin E promotes a healthy immune system and may help to prevent the dip in immune function that may occur right after exercise. Vitamin E may also help to ease muscle cramps.
How much is usually taken by athletes?
Most controlled studies show that vitamin E does not benefit exercise performance,1 except possibly at high altitudes. A controlled study of mountain climbers at high altitude found that 400 IU per day of vitamin E improved anaerobic threshold, a physiological measure of aerobic endurance.2 More research is needed to determine whether this improvement might affect actual performance of athletic activities at high altitudes.
Strenuous exercise increases production of harmful substances called free radicals, which can damage muscle tissue and result in inflammation and muscle soreness. Antioxidants such as vitamin E might reduce this damage by neutralizing free radicals before they can damage the body.3 4 While some research has reported that vitamin E supplementation in the amount of 800 to 1200 IU per day reduces biochemical measures of free radical activity and muscle damage caused by strenuous exercise,5 6 7 several studies have not found such benefit,8 9 10 11 and no research has investigated the effect of vitamin E on performance-related measures of strenuous exercise recovery.
Are there any side effects or interactions?
Vitamin E toxicity is very rare and supplements are widely considered to be safe. The National Academy of Sciences has established the daily tolerable upper intake level for adults to be 1,000 mg of vitamin E, which is equivalent to 1,500 IU of natural vitamin E or 1,100 IU of synthetic vitamin E.12
In a double-blind study of healthy elderly people, supplementation with 200 IU of vitamin E per day for 15 months had no effect in the incidence of respiratory infections, but increased the severity of those infections that did occur.13 For elderly individuals, the risks and benefits of taking this vitamin should be assessed with the help of a doctor or nutritionist.
In contrast to trials suggesting vitamin E improves glucose tolerance in people with diabetes, one trial reported that 600 IU per day of vitamin E led to impairment in glucose tolerance in obese people with diabetes.14 The reason for the discrepancy between reports is not known.
In a double-blind study of people with established heart disease or diabetes, participants who took 400 IU of vitamin E per day for an average of 4.5 years developed heart failure significantly more often than did those taking a placebo.15 Hospitalizations for heart failure occurred in 5.8% of those in the vitamin E group, compared with 4.2% of those in the placebo group, a 38.1% increase. Considering that some other studies have shown a beneficial effect of vitamin E against heart disease, the results of this study are difficult to interpret. Nevertheless, individuals with heart disease or diabetes should consult their doctor before taking vitamin E.
A review of 19 clinical trials of vitamin E supplementation concluded that long-term use of large amounts of vitamin E (400 IU per day or more) was associated with a small (4%) but statistically significant increase in risk of death.16 Long-term use of less than 400 IU per day was associated with a small and statistically nonsignificant reduction in death rates. This research has been criticized because many of the studies on which it was based used a combination of nutritional supplements, not just vitamin E. For example, the adverse effects reported in some of the studies may have been due to the use of large amounts of zinc or synthetic beta-carotene, and may have had nothing to do with vitamin E. It is also possible that long-term use of large amounts of pure alpha-tocopherol may lead to a deficiency of gamma-tocopherol, with potential negative consequences. For that reason, some doctors recommend that people who need to take large amounts of vitamin E take at least part of it in the form of mixed tocopherols.
Patients on kidney dialysis who are given injections of iron frequently experience “oxidative stress.” This is because iron is a pro-oxidant, meaning that it interacts with oxygen molecules in ways that may damage tissues. These adverse effects of iron therapy may be counteracted by supplementation with vitamin E.17
A diet high in unsaturated fat increases vitamin E requirements. Vitamin E and selenium work together to protect fat-soluble parts of the body.
Are there any drug
interactions?
Certain medicines may interact with vitamin E. Refer to drug interactions for a list of those medicines.
*Athletes and fitness advocates may claim benefits for vitamin E based on their personal or professional experience. These are individual opinions and testimonials that may or may not be supported by controlled clinical studies or published scientific articles on vitamin E. For more complete and detailed information, including references and safety information, see Vitamin E as a nutritional supplement.
1. Tiidus PM, Houston ME. Vitamin E status and response to exercise training. Sports Med 1995;20:12–23 [review].
2. Simon-Schnass I, Pabst H. Influence of vitamin E on physical performance. Int J Vitam Nutr Res 1988;58:49–54.
3. Kanter M. Free radicals, exercise and antioxidant supplementation. Proc Nutr Soc 1998;57:9–13 [review].
4. Dekkers JC, van Doornen LJ, Kemper HC. The role of antioxidant vitamins and enzymes in the prevention of exercise-induced muscle damage. Sports Med 1996;21:213–38 [review].
5. Itoh H, Ohkuwa T, Yamazaki Y, et al. Vitamin E supplementation attenuates leakage of enzymes following 6 successive days of running training. Int J Sports Med 2000;21:369–74.
6. McBride JM, Kraemer WJ, Triplett-McBride T, Sebastianelli W. Effect of resistance exercise on free radical production. Med Sci Sports Exerc 1998;30:67–72.
7. Evans WJ. Vitamin E, vitamin C, and exercise. Am J Clin Nutr 2000;72:647S–52S [review].
8. Dawson B, Henry GJ, Goodman C, et al. Effect of Vitamin C and E supplementation on biochemical and ultrastructural indices of muscle damage after a 21 km run. Int J Sports Med 2002;23:10–5.
9. Beaton LJ, Allan DA, Tarnopolsky MA, et al. Contraction-induced muscle damage is unaffected by vitamin E supplementation. Med Sci Sports Exerc 2002;34:798–805.
10. Petersen EW, Ostrowski K, Ibfelt T, et al. Effect of vitamin supplementation on cytokine response and on muscle damage after strenuous exercise. Am J Physiol Cell Physiol 2001;280:C1570–5.
11. Kanter MM, Nolte LA, Holloszy JO. Effects of an antioxidant vitamin mixture on lipid peroxidation at rest and postexercise. J Appl Physiol 1993;74:965–9.
12. Panel on Dietary Antioxidants and Related Compounds, Food and Nutrition Board, Institute of Medicine, National Academy of Sciences. Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids. Washington, D.C.: National Academy Press, 2000, 249–59.
13. Graat JM, Schouten EG, Kok FJ. Effect of daily vitamin E and multivitamin-mineral supplementation on acute respiratory tract infections in elderly persons: a randomized controlled trial. JAMA 2002;288:715–21.
14. Skrha J, Sindelka G, Kvasnicka J, Hilgertova J. Insulin action and fibrinolysis influenced by vitamin E in obese type 2 diabetes mellitus. Diabetes Res Clin Pract 1999;44:27–33.
15. Zoler ML. Supplemental vitamin E linked to heart failure. Fam Pract News 2003 (October 1):28 [News report].
16. Miller ER III, Pastor-Barriuso R, Dalal D, et al. Meta-analysis: high-dosage vitamin E supplementation may increase all-cause mortality. Ann Intern Med 2005;142:37–46.
17. Roob JM, Khoschsorur G, Tiran A, et al. Vitamin E attenuates oxidative stress induced by intravenous iron in patients on hemodialysis. J Am Soc Nephrol 2000;11:539–49.