In spite of a lack of scientific support, many people take supplement as "nutritional insurance," just in case their diet is inadequate. There is no great risk here and possibly even some benefit as long as mega-doses are avoided. This is underlined by a National Cancer Institute study published in 2007 that showed a link between excessive use of multivitamin supplements (more that one multivitamin a day) and an increased risk of advanced prostate cancer. There was no problem with men who took just one daily multivitamin; in fact, there seemed to be a slightly protective effect against the disease.
So where does this leave us?
The scientific consensus is that vitamin C in the 250 to 500 milligram range is safe enough, as is vitamin E in doses up to 400 IU. Vitamin A should not exceed 4,000 IU, and it is preferable if some of this comes from beta-carotene, its precursor. The best case for supplementation can be made for vitamin D and the B vitamins, particularly folic acid. We have seen the tantalizing data linking vitamin D with protection against various cancers and the studies that suggest the risk of dementia is reduced with adequate B vitamin intake. Supplements containing about 2 milligrams of vitamin B6, 6 micrograms of B12 and 400 micrograms of folic acid can compensate for a lack of these in the diet. As far as vitamin D goes, many researchers now believe that we should be getting about 1,000 IU a day, an amount that is hard to achieve without supplements.
Although vitamin purveyors often clamour about their products being of higher quality than others, differences between the major brands have no particular significance. Often, the same manufacturer produces vitamins for various distributors, which are then sold at varying prices. While the actual value of taking vitamin supplements is questionable, there is no doubt that for many people they provide comfort and hope, which may be valuable at any price.
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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.
