On Dec. 17, there was widespread coverage in the news media of an editorial that appeared in the Annals of Internal Medicine (Annals), under the title, "Enough is enough: stop wasting money on vitamin and mineral supplements."(1) The authors of the editorial concluded, "We believe that the case is closed -- supplementing the diet of well-nourished adults with (most) mineral or vitamin supplements has no clear benefit and might even be harmful. These vitamins should not be used for chronic disease prevention. Enough is enough." However, the editorial appears to be biased and to lack scholarship, as it is based on selective reporting and a superficial analysis of the vast and complex body research on the health effects of nutritional supplements.
The editorial focused mainly on three studies published in that issue of the Annals. The first study found that supplementing with large doses of vitamins and minerals after a heart attack reduced the recurrence rate of cardiovascular events (such as heart attack, stroke, or heart surgery) by 11 percent, compared with a placebo. (2) However, because this reduction was not statistically significant, the editorial concluded (incorrectly) that the treatment was ineffective. The failure to demonstrate that an effect is statistically significant is not the same as demonstrating the absence of an effect. The correct conclusion is that the nutritional supplement reduced the number of cardiovascular events by 11 percent, but because this reduction was not statistically significant, we are less than 95 percent certain that the effect was real (as opposed to being due to chance).
The second study in the Annals found that daily use of a low-potency multivitamin (Centrum Silver) for an average of 8.5 years had no effect on cognitive function in elderly men participating in the large Physicians' Health Study II. (3) However, two other recent double-blind trials (which were not mentioned in the editorial) found positive effects of vitamins. In one of those studies, daily supplementation with 400 mcg of folic acid and 100 mcg of vitamin B12 significantly improved cognitive function in elderly men. (4) The other study showed that daily supplementation with 800 mcg of folic acid, 500 mcg of vitamin B12, and 20 mg of vitamin B6 slowed the rate of brain atrophy in elderly individuals suffering from mild cognitive impairment. (5) There are two potentially important differences between these positive studies and the negative study cited in the editorial. One difference is that the amount of vitamin B12 in Centrum Silver (25 mcg) is much lower than the amount used in the positive studies (100 and 500 mcg, respectively). Loss of cognitive function is a well-known effect of vitamin B12 deficiency. Although all of the study supplements provided more than the Recommended Dietary Allowance for vitamin B12 (2.4 mcg per day), recent research has shown that many elderly people need unusually large amounts of this vitamin (500 mcg per day or more in some cases) to achieve optimal vitamin B12 nutritional status. (6) The other difference is that several aluminum-containing artificial coloring agents are present in Centrum Silver (FD&C Blue 2 Aluminum Lake, FD&C Red 40 Aluminum Lake, and FD&C Yellow 6 Aluminum Lake), and these chemicals have the potential to adversely affect cognitive function. Artificial coloring agents are known to have negative effects on the behavior of children, (7) although these chemicals have not been well studied in adults. Moreover, there is evidence that long-term aluminum exposure can contribute to the development of Alzheimer's disease.(8) The ineffectiveness of a low-potency supplement that contains extraneous and potentially harmful additives does not negate the beneficial effects of higher-potency supplements reported in other trials.
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