Antioxidants and Stroke Prevention
Clinical Briefs
With Comments from John La Puma, MD, FACP
Antioxidants and Stroke Prevention
December 2000; Volume 3; 144
Source: Yochum LA, et al. Intake of antioxidant vitamins and risk of death from stroke in postmenopausal women. Am J Clin Nutr 2000;72:476-483.
"Antioxidant vitamins may play a role in the prevention of stroke because they scavenge free radicals and prevent LDL oxidation. Epidemiologic studies that have examined this relation produced conflicting results. We examined the association between antioxidant vitamin intakes and death from stroke. This was a prospective cohort study of 34,492 postmenopausal women. During follow-up, 215 deaths from stroke were documented. Total vitamin A, carotenoid, and vitamin E intakes were not associated with death from stroke after multivariate adjustment. Relative risks (RR) and 95% confidence intervals (CI) of the highest compared with the lowest category were 0.79 (0.45, 1.38; P for trend = 0.33) for vitamin A; 0.80 (0.45, 1.40; P for trend = 0.40) for carotenoids; and 0.91 (0.55, 1.52; P for trend = 0.86) for vitamin E. The test for trend for total vitamin C intake was significant, although the association appeared somewhat U-shaped, not monotonic. An inverse association was seen between death from stroke and vitamin E intake from food. RRs (and 95% CIs) of death from stroke from the lowest to highest intake categories were 1.0, 0.80 (0.51, 1.26), 0.93 (0.58, 1.49), 0.67 (0.39, 1.14), 0.40 (0.20, 0.80); P for trend = 0.008. The results suggest inverse associations between death from stroke and intakes of the most concentrated vitamin E food sources consumed by this cohort: mayonnaise, nuts, and margarine. Our results suggest a protective effect of vitamin E from foods on death from stroke but do not support a protective role for supplemental vitamin E or other antioxidant vitamins. However, given the number of deaths from stroke in the present cohort, a small-to-moderate association could not be ruled out."
COMMENT
Vitamin E is one of the hardest vitamins to obtain from food if you’re watching calories. Because it’s fat soluble, and is better absorbed with a little fat, it seems awfully convenient to take in one of those gel capsules, with barely 5 calories a pop, and do your bit for death-from-stroke prevention. And mayonnaise, nuts, and margarine sound appetizing to few eaters thinking about their stroke potential. Could it be true?
Maybe. Three other large epidemiological studies published this year are contradictory. In the other trials, vitamin E had no affect on stroke incidence. Here, supplemental intake of vitamin E was not protective either; however, food intake of vitamin E was protective of death from stroke. The women in the highest quintile of food intake (margarine seven times per week, nuts and seeds four times per month, mayonnaise or creamy salad dressing three times per week) had the lowest relative risk of death from stroke, though these trends were not statistically significant.
The RDI for vitamin E was just raised to 15 mg/d (or 22 IU/d). Natural vitamin E is better absorbed than synthetic, although most supplement studies have been performed with synthetic vitamin E, which is in many multivitamins. Most foods have mixed tocopherols—alpha, beta, gamma, and delta. The best food sources are, in fact, oils and nuts. But if you don’t feel like snacking on an ounce of sunflower seeds (14.25 mg), or 1.5 oz of almonds (6.72 mg) and 1.5 oz of hazelnuts (6.78 mg), or a tablespoon of mayonnaise (1.65 mg) or margarine (1.06 mg) just pour yourself a cup of Total® Raisin Bran (30 IU).
Recommendation
Encourage people who want to prevent stroke to get their vitamin E through food if and only if they substitute vitamin E calories for other calories. Prescribe a time-limited trial for them. More mayonnaise and margarine are not good things for most people, no matter how much vitamin E they contain.
December 2000; Volume 3; 144
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