Vitamin E Supplementation in Healthy Elderly Subjects
Abstract & Commentary
Synopsis: The results of this randomized clinical trial conducted in women and men older than 65 years indicated that a level of vitamin E greater than currently recommended enhanced clinically relevant in vivo indices of T-cell-mediated function.
Source: Meydani SN, et al. JAMA 1997;277:1380-1386;1398-1399.
Aging is accompanied by altered immune function, which confers vulnerability to infectious and neoplastic diseases, prolonged periods of recovery after illness, and greater morbidity. Altered T-cell-mediated immunity is reflected in the inability of many elderly to mount a delayed-type hypersensitivity skin response (DTH). DTH is the best predictor of sepsis-related death. Another important aspect of aging is a decreased antibody response to foreign antigens and an increase in self antigens. Studies in old mice suggest that vitamin E may improve these aspects of immune function. Thus, the present study was undertaken to determine if vitamin E supplementation would enhance immune responsivity in older men and women. Eighty-nine healthy older adults participated in a randomized, double-blind, placebo-controlled protocol with placebo or 60, 200, or 800 mg/d of vitamin E. The lowest dose is twice the U.S. recommended daily allowance of vitamin E. The highest dose was chosen based on a previous short-term study. The intermediate dose is found in many over-the-counter vitamin E supplements. The investigators found that supplementation with vitamin E improved DTH and antibody response to challenge without associated adverse side effects.
COMMENT BY SARAH L. BERGA, MD
Does vitamin E, otherwise known as a-tocopherol, belong on the list of agents that will retard aging? The present study suggests that it does. Vitamin E is an antioxidant that inhibits prostaglandin E2. Prostaglandin E2 release increases with age and contributes to age-related dysregulation of the immune response. Other evidence suggests that vitamin E confers cardioprotection by reducing LDL cholesterol oxidation and platelet aggregation.
Unfortunately, vitamin E is relatively difficult to obtain from food. It is found in vegetable and seed oils, nuts, seeds, and wheat germ. Thus, some nutrition experts have concluded that vitamin E supplementation is the logical method to provide adequate levels of this nutrient.
Nonetheless, even if vitamin E supplements are taken, it is important to eat the recommended five servings of fruits and vegetables each day, because studies suggest that vitamin E alone is insufficient. Another important nutrient is vitamin A, which is found in fruits and vegetables. Apparently, vitamin A is a marker for other related compounds found in fruits and vegetables, and when vitamin A is given as a supplement, these other important agents are not obtained. Thus, it is only vitamin E that is recommended to be taken as a supplement. The general guideline is to still eat a balanced diet if for no other reason than to obtain the important nutrients that we have yet to identify.
As more studies of this type are done, patients will expect us to have knowledge of them. Older women want advice about which supplements are likely to ameliorate age-related vulnerabilities. Stay tuned.
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