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Vitamin E Supplements - Will They Prevent Diabetes?

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Updated November 19, 2010

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

Vitamin E is an antioxidant vitamin that is thought to play a role in protecting your cells against the effects of free radicals, which can damage cells and may contribute to the development of cardiovascular disease and cancer. Vitamin E has also been shown to play a role in immune function, in DNA repair, and other metabolic processes.

But if you're wondering if you should take Vitamin E supplements to prevent heart disease, cancer or diabetes, current research does not necessarily support this practice. The latest randomized clinical trials on Vitamin E and heart disease have raised questions about the efficacy of vitamin E supplements in the prevention of heart disease. The American Cancer society recently released the results of a long-term study finding that subjects who regularly consumed vitamin E supplements for longer than 10 years had a reduced risk of death from bladder cancer, but at this time researchers cannot confidently recommend vitamin E supplements for the prevention of cancer because the evidence on this issue is generally inconsistent and limited. As for vitamin E and diabetes, according to the American Diabetic Association, "large, long-term human trials of vitamin E supplements have failed to prevent type 2 diabetes."

In addition, a large meta-analysis published in 2005 reported that mortality was significantly increased in people who took more than 400 IU of vitamin E per day. Higher doses of vitamin E was associated with an increased risk of hemorrhagic stroke and heart failure. Given the lack of evidence that high-dose vitamin E does anything useful, most experts are now recommending that people stick to less than 400 IU/day, even though the stated tolerable upper limit of Vitamin E is still 1,000. If you do ever take a supplement, this is good to note. Also note that it would be virtually impossible to exceed recommended intakes of Vitamin E on a daily basis when simply incorporating Vitamin E-rich foods as a part of a well-balanced diet.

Another thought on supplements: though it is unclear why, more and more studies are showing that taking an isolated antioxidant doesn't match the benefits of eating foods that contain the same antioxidant. One theory on this is that antioxidants have a synergistic effect and may need other nutrients to work in tandem with them. So you may not want to run out to buy Vitamin E supplements, but you certainly don't want to stop eating nutritious whole foods that are high in antioxidants, like Vitamin E, either. It may be that some undiscovered compound in antioxidant-rich foods is actually what is responsible for their health benefits, and you wouldn't want to miss out on whatever that is.

Common food sources of Vitamin E are vegetable oils, nuts, green leafy vegetables, and fortified cereals. The recommended daily allowance for Vitamin E is much less than 400IU. It's only 23IU and can be provided in a manageable 2 ounces of almonds or 1 Tbsp of wheat germ, or a heftier 3 oz of sunflower seeds, 3 Tbsp of sunflower oil, 8 Tbsp of fortified peanut butter, or about 15 cups of raw spinach. In addition, always check food labels, especially if foods are labeled as "fortified" or "rich in antioxidants:" while even detailed food labels do not typically list Vitamin E content, if a food is fortified with Vitamin E it may be documented. >

Finally, don't feel that it is necessary to try get your RDA of Vitamin E in one shot. A well balanced diet that includes foods rich in other healthy nutrients is the best way to reap the health benefits of any nutrient, including Vitamin E. Try sprinkling almonds or sunflower seeds on top of your salads, using sunflower oil in cooking, snacking on peanut butter and apples, and adding chopped spinach into cooked foods like rice, spaghetti sauce, lasagna, or meatloaf.

References

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  4. Institute of Medicine, Food and Nutrition board. Dietary Reference Intakes: Vitamin C, Vitamin E, Selenium, and Carotenoids. National Academy Press, Washington, DC, 2000.
  5. National Research Council, Food and Nutrition Board. Recommended Dietary Allowances, 10th ed. Washington, DC: National Academy Press, 1989.
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  11. Leske MC, Chylack LT Jr., He Q, Wu SY, Schoenfeld E, Friend J, Wolfe J. Antioxidant vitamins and nuclear opacities: The longitudinal study of cataract. Ophthalmology 1998;105:831-6.
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  13. Meydani SN, Meydani M, Blumberg JB, Leka LS, Pedrosa M, Diamond R, Schaefer EJ. Assessment of the safety of supplementation with different amounts of vitamin E in healthy older adults. Am J Clin Nutr 1998;68:311-8.

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