Multivitamins and vitamin supplements can benefit certain populations of people who don't get enough nutrients in their diets. Adding a daily vitamin E supplement might be a good idea for those who are on low-fat diets or have malabsorption disorders. Talk to your doctor about whether you should add a vitamin E supplement to meet your daily recommendation without exceeding the recommended upper limit for risk of toxicity.
Functions
Vitamin E comes in a number of chemical forms, each with distinctive antioxidant properties. These compounds are fat-soluble and are absorbed and transferred into the bloodstream by fat globules called chylomicrons before being stored in fat tissues throughout the body. The chemical compounds of vitamin E perform a variety of functions. One of the most notable is its function as an antioxidant, protecting cells from damage by free radicals, either created when the body converts food to energy, or through exposure to environmental hazards such as pollution or cigarette smoke, according to the National Institutes of Health Office of Dietary Supplements. Vitamin E also performs cellular and metabolic functions in the immune system and works with other enzymes in the body to suppress damaging acids.
Vitamin E Supplements
Vitamin E is found naturally in a number of foods, including seeds, nuts, some oils and many fruits and vegetables. This natural vitamin E is called d-alpha-tocopherol. Alpha-tocopherol is the only form recognized as meeting human requirements, even though the majority of vitamin E in the American diet is in the form of gamma-tocopherol, which is found in a number of vegetable oils. For supplements, a synthetic vitamin E, called dl-alpha-tocopherol, is used. One benefit to taking a vitamin E dietary supplement is the isolation of the beneficial alpha-tocopherol form of the vitamin, though mixed tocopherol supplements are also available.
Recommendation and Conversion
Adult men and women are advised to get 15 mg, or 22.4 IU, per day of vitamin to meet their adequate intake, according to guidelines cited by the University of Maryland Medical Center. Breast-feeding women need 19 mg, or 28.4 IU. Synthetic vitamin E does not absorb in the body as readily as natural vitamin E, so it is advised to consume 50 percent more synthetic as natural vitamin E to get the same amount of the nutrient. As of August, 2011, the amount of vitamin E listed on dietary supplement labels is in international units (IUs). This is a measure of how the vitamin performs in your body, rather than a weight. One milligram of alpha-tocopherol is equal to 1.49 IU of the natural form of vitamin E, or 2.22 IU of the synthetic form, while one IU of alpha-tocopherol is equal to 0.67 mg of natural vitamin E, or 0.45 mg of synthetic vitamin E.
Deficiency and Toxicity
While it appears that most Americans may get less than their recommended daily dose of vitamin E in their diet, serious deficiency is rare and mostly limited to premature babies, those on very low-fat diets or those with nutrient absorption disorders. As vitamin E is fat soluble, it is not readily removed from the body as waste. High doses of supplements can lead to hemorrhagic effects; the Food and Nutrition Board recommends an upper limit dosage not to exceed 1,000 mg per day. However, a 2004 study led by Edgar R. Miller III, M.D., Ph.D at John Hopkins University School of Medicine suggested that a daily, long-term dose of 400 IU per day or more increases a person's risk of death. Most multivitamins contain 30 to 60 IU per dose.
References
- National Institutes of Health, Office of Dietary Supplements; Vitamin E; June, 2011
- University of Maryland Medical Center; Vitamin E; December, 2009
- Linus Pauling Institute at Oregon State University; Vitamin E; January, 2011
- Johns Hopkins University Medicine; Study Shows High-Dose Vitamin E Supplements May Increase Risk of Dying; David March; November, 2010
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