A Reuters headline asks, “Could multivitamins raise breast cancer risk?” based on a decade-long study published in the American Journal of Clinical Nutrition which followed 35,000 Swedish women and their self-reported supplement use.
“This is a horrible headline, and a typical example of what epidemiologists are forced to resort to in order to get attention for their work, especially when it is an observational study of nutrition,” says Dr. Ross. “Many people like to take multivitamins because they imagine that there’s some magical health benefit, but with a few exceptions, almost every study I’ve seen about these supplements has failed to show that they have any beneficial effect, and some have proven harmful.
“When you consider that this study is based on people reporting their own use of vitamins over a decade, and that the increase in breast cancer risk that they found was only 19%, I have to ask you: does this study warrant this headline? It’s only slightly above the level of junk science because of its size, but to extrapolate a 19% increase in risk based on self-reporting is absurd.”