ANTIOXIDANT SUPPLEMENTS MAY HAVE CARDIOVASCULAR BENEFIT IN AT- RISK WOMEN
This article was originally published in The Tan Sheet
ANTIOXIDANT SUPPLEMENTS MAY HAVE CARDIOVASCULAR BENEFIT IN AT- RISK WOMEN, according to a study presented by JoAnn Manson, MD, Brigham and Women's Hospital, et al. at the American Heart Association's 66th Scientific Sessions in Atlanta, Ga. on Nov. 8- 11. Women in the highest quintile of antioxidant intake may reduce their risk for myocardial infarction by 33% and for stroke by 71% compared with women in the lowest quintile of intake, Manson et al. indicated. The epidemiological study evaluated 1,795 female nurses with "a prior history of myocardial infarction (MI), angina and/or coronary revascularization" who were assessed for "a total antioxidant score (a quantitative score based on pooling the intake of vitamins C, E, carotene and riboflavin)." Manson et al. said that "data suggest that a higher total antioxidant vitamin score is associated with a reduced risk of subsequent MI and stroke among high-risk women." Antioxidant intake was determined through "a semiquantitative food frequency questionnaire" administered to women aged 34 to 59 in 1980, Manson et al. explained. The subjects were monitored for 10 years following the original questionnaire. "During 16,695 person-years of follow-up," 122 MIs and 40 strokes were documented, the researchers said. "Among women in the highest quintile of antioxidant vitamin score, compared with those in the lowest, the age- and smoking- adjusted relative risk of MI was .67 . . . and of stroke was .29" at a 95% confidence interval, Manson et al. reported. "Multivariate control for other [cardiovascular disease] risk factors did not materially alter these results." The women consuming the highest amounts of dietary supplements suffered 17 heart attacks and three strokes, while the women consuming the smallest amounts suffered 26 heart attacks and 12 strokes, the researchers reported. In a separate prepared statement, Manson said that "specific antioxidants seemed to make different contributions to risk reduction. For heart attack, the strongest contributor was vitamin E, while carotene had the greatest role in reducing stroke risk." Previous studies also have cited vitamin E as having a cardioprotective benefit ("The Tan Sheet" May 24, p. 10). Manson et al. pointed out that "antioxidant vitamins have been postulated to prevent atherosclerosis by inhibiting the oxidation of lipoproteins. Although benefits have been reported in the primary prevention of cardiovascular disease in several epidemiologic studies, evidence from secondary prevention has been sparse. High-risk individuals would have the most to benefit from such interventions, if effective." However, Manson emphasized in her statement that the study findings "do not prove that antioxidants help prevent heart attacks and strokes . . . but they strongly support recommendations to eat more fruits and vegetables, the primary source of antioxidants." She added: "We can't yet say that antioxidant vitamins, per se, as opposed to foods that are high in antioxidants, can reduce the risk of stroke or heart attack . . . at this point, I couldn't recommend that people buy dietary supplements." Manson's conclusions mirror comments made by researchers at FDA's recent conference on antioxidants and cancer/cardiovascular disease. Some conference participants concluded that there is a lack of data showing the efficacy of dietary supplements in disease prevention ("The Tan Sheet" Nov. 8, p. 16). Another study presented at the AHA session by Michael Miller, MD, University of Maryland, et al. investigated the connection between elevated iron storage levels and the risk for coronary disease. The study evaluated 130 matched subjects pulled from 48,000 autopsies performed between 1889 and 1993 at Johns Hopkins Hospital, and found no positive relationship between elevated iron levels and increased risk. The study findings suggest that "iron overload patients are not at increased risk for coronary disease and suggest that other factors may account for the coronary disease rate previously reported [at AHA] and primarily attributed to elevated iron storage levels," Miller et al. said.
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