Dr. Bjelakovic decided to look into this possibility by mounting a second meta-analysis. His team tracked hundreds of published trials on the health effects of beta-carotene, vitamin A, vitamin C, vitamin E and selenium supplements, and whittled these down to 68 that met the criteria for proper blinded, randomized, placebo-controlled trials. Some studies used low doses of supplements, some high; some lasted months, other many years. Some used single antioxidants, others used various combinations. But the strength of a anti-meta-analysis lies in pooling results from many studies, evening out variables and allowing an overall conclusion to emerge. As in his previous study, Bjelakovic found no benefit from the supplements, and as before, he noted an increase in mortality among supplement takers. The data appear to be robust. More than 230,000 participants were involved in the 68 trials, 21 of which focused on healthy subjects who were taking antioxidants to prevent disease.
No surprise, the salvo of criticism has been furious. Many relevant trials were excluded, critics claim. Causes of death were not determined and may have had nothing to do with supplements. Subjects took numerous other supplements and prescription drugs that could have clouded the issue. There is no biological mechanism that can explain potential harm by antioxidants. Well, that one is not exactly true. Certain white blood cells, for example, attack toxins by generating free radicals, and it is possible that antioxidants can interfere with this activity. No doubt, some of the criticism aimed at the Bjelakovic analysis is valid, but given that so many subjects and so many studies were involved, any significant benefit from the antioxidants examined would have become apparent. Incidentally, Dr. Bjelakovic and his group received no funding from any commercial enterprise and appear to have no reason to either knock or support dietary supplements.
Better to get our vitamins from food than from pills
While I do not think that vitamin supplements are killing us, there is mounting evidence that it is better to get our vitamins from food than from pills. It seems that there is an almost magical blend of antioxidants, minerals and probably unrecognized other ingredients in fruits, vegetables and whole grains that cannot be replicated in supplements. A 13-member expert panel of the National Institutes of Health in the United States concluded that there is insufficient evidence for or against recommending vitamin supplements except in three cases. Supplementation with B vitamins in women of child-bearing age is beneficial, as is supplementation with calcium and vitamin D in postmenopausal women to prevent bone fractures. And the progression of macular degeneration can be reduced with a mix of beta-carotene, zinc, vitamin C and vitamin E. Note that taking supplements to prevent heart disease is not one of the recommendations. That may surprise many people because it has become almost dogma that certain vitamin and mineral supplements can prevent hardening of the arteries (atherosclerosis), which can lead to heart disease.
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Excerpted from An Apple a Day: The Myths, Misconceptions and Outright Exaggerations about Diet, Nutrition and the Foods We Eat. Published by HarperCollins Publishers Ltd. Copyright 2007 by Dr. Joe Schwarcz. All rights reserved. Reprinted by permission of HarperCollins Publishers Ltd.
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