Tuesday, March 30, 2010

Do multivitamins increase breast cancer risk? by Jerry Brainum

I've always found it curious that the popular media loves to publicize negative studies related to nutrition, while choosing to ignore the plethora of regularly published studies that does support nutritional supplements. A case in point is a soon-to-be-published study that found an extremely obscure connection between women who ingest multivitamins and an increased risk of breast cancer. The study was a 10-year look at 35,000 Swedish women, ages 49 to 83, who started out with no signs of cancer. At the end of 10 years, 974 of the women had diagnosed breast cancer. The authors of the study calculated that women who reported using multivitamin supplements were 19% more likely that non-users to develop breast cancer.
     The above portion of the study was reported in the popular media, such as television and newspapers. What wasn't reported was that the majority of women who reported using multivitamins didn't show any increased rates of breast cancer.Another study of 100,000 women over eight years found no connection between multivitamin usage and any type of cancer or heart disease when compared to non-users.The authors of the new study think that because multivitamin use is linked to increased breast density in women, this may be a cause. But there is no actual cause and effect proof of this increased density promoted by vitamins and minerals. Another factor, they say, could be folic acid, a B-complex vitamin that some studies associate with breast cancer onset. But other studies show a protective effect offered by folic acid in this regard.
Another thing to consider is that this was a cohort study, or a study of a large population. Such studies are notoriously inaccurate. The authors of the study says that,"If you eat  healthy and varied diet, there is no need to use multivitamins." I wouldn't argue against that statement, although some vitamins, such as vitamin E, cannot be obtained in sufficient quantity in any kind of diet. On the other hand, I would also suggest that since many women don't eat such varied diets, they would experience more long-term health risks by not taking a good multivitamin supplement.
Larsson, S. et al Multivitamin use and breast cancer incidence in a prospective cohort of Swedish women.Am J Clin Nutr 2010: in press.

©,2012 Jerry Brainum. Any reprinting in any type of media, including electronic and foreign is expressly prohibited

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