Negative Results in Antioxidant-Heart Study Challenged
Supplementation with vitamins E and C and beta-carotene for five years was of no benefit to individuals at high risk of dying from heart disease, according to an article in the July 6 issue of Lancet (2002;360:20–33). This report adds to the growing list of conflicting and often confusing studies on whether antioxidant supplementation can prevent heart disease.
In the new study, more than 20,000 British adults aged 40 to 80 years, who were considered to be at high risk because of a history of heart disease, hardening of the arteries (atherosclerosis), diabetes, or high blood pressure, were randomly assigned to receive antioxidant supplements (600 IU of vitamin E, 250 mg of vitamin C, and 20 mg of beta-carotene per day) or a placebo for five years. Although blood levels of these vitamins increased in the group that received the supplement, there was no difference between the antioxidant group and the placebo group in the five-year incidence heart attacks, strokes, or death due to heart disease or other causes. In addition, the incidence of cancer did not differ between the two groups.
Although these negative results are consistent with the findings from a few other studies, some research has demonstrated a clear benefit from antioxidant supplementation. For example, in a 1996 study published in Lancet, supplementation of heart patients with vitamin E (400 or 800 IU per day) for approximately 18 months reduced the incidence of heart attacks by 77%. Several other studies have shown that vitamin E increases pain-free walking distance in people with atherosclerosis of the lower extremities.
The conflicting results seen in various antioxidant studies may be due to differences in nutritional status among the different study populations. There is good evidence that a wide range of nutrients other than vitamins E and C and beta-carotene are important for maintaining a healthy heart and blood vessels. Magnesium, vitamin B6, folic acid, selenium, copper, zinc, and chromium have each been shown in either human or animal studies, or both, to be beneficial for the prevention or treatment of cardiovascular disease. Nutrients work in the body as a team, and all of them must be present in adequate amounts in order to promote good health. If magnesium, for example, were the weakest link in the nutritional chain, one would not expect antioxidants to do much good until the magnesium deficiency was corrected. In fact, magnesium deficiency has been shown to be quite common among people with heart disease, atherosclerosis, diabetes, and high blood pressure—the same conditions that the participants in the new study suffered from.
Rather than testing only one or a few nutrients at a time, researchers should use a supplement that contains all of the nutrients known to promote heart health. Based on clinical experience and review of hundreds of scientific papers, I believe that such a comprehensive nutritional supplement (ideally, tailored to each person's individual needs) would be shown to be of significant benefit for heart patients.
Alan R. Gaby, MD, an expert in nutritional therapies, served as a member of the Ad-Hoc Advisory Panel of the National Institutes of Health Office of Alternative Medicine. He is the Medical Editor for Clinical Essentials Alert, is the author of Preventing and Reversing Osteoporosis (Prima, 1994), and co-author of The Natural Pharmacy, 2nd Edition (Healthnotes, Prima, 1999), the A–Z Guide to Drug-Herb-Vitamin Interactions (Healthnotes, Prima, 1999), Clinical Essentials Volume 1 and 2 (Healthnotes, 2000), and The Patient’s Book of Natural Healing (Prima, 1999). Currently he is the Endowed Professor of Nutrition at Bastyr University of Natural Health Sciences, Kenmore, WA.
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