Is multivitamin use really associated with an increased risk of breast cancer?

Image Credit: Image Credit: United States Navy ID 110429-F-NJ219-021 / Wikimedia Commons

I’m bit disappointed with your presentation, and I’m wondering why you exactly choose this multi vitamin study to underpin your conclusion in this video. The Swedish cohort was from 2010 and in April of this year a meta-analysis, which is scientifically stronger in terms of proof, concluded : “Multivitamin use is likely not associated with a significant increased or decreased risk of breast cancer, but these results highlight the need for more case-control studies or randomized controlled clinical trials to further examine this relationship.” […]

Louis / Originally commented on Multivitamin supplements and breast cancer


Thank you so much Louis for taking the time to contribute! It is such a relief to see that meta-analysis come out. This video was queued up from my volume 5 DVD, reviewing the peer-reviewed nutritional science published between Spring 2010 to Spring 2011, and so I just missed it (it wasn’t indexed by the National Library of Medicine until August 19, 2011).

Of course negative findings don’t automatically “cancel” out positive findings. As one of my research preceptors once quipped: “if two people drill for oil in Texas and one finds oil and the other does not, one can’t conclude that the question of whether or not there is oil in Texas remains undetermined.” Similarly, the conclusion from the 2010 study profiled in the video is not necessarily invalidated: “These results suggest that multivitamin use is associated with an increased risk of breast cancer. This observed association is of concern and merits further investigation.” But it’s nice to know that if there is an effect it’s not one that has been replicated!

The critical question remains: should women take multivitamins or not? That depends on the risks versus benefits like any other life decision. Since both the risks and the benefits appear equivocal (see for example the National Institutes of Health State-of-the-Science Conference Statement on multivitamins, PDF here) I agree with the Cleveland Clinic Journal article I featured and would recommend women take the money they would have spent on the pills and instead buy some produce with more proven benefits (see my Breast Cancer and Diet post, for example). A similar recommendation can be made for men (as a similar meta-analysis likewise thankfully casts doubt on the multivitamin link there as well).

Until we know more, I agree with the conclusion from the meta-analysis you cite: “Until further studies assist in clarifying the association between multivitamin use and increased or decreased risk of breast cancer, health-care professionals should open discussions with their patients regarding multivitamin use and risk of breast cancer.”

Addendum: Reported in today’s Archives of Internal Medicine, a study from Iowa Women’s Health Study suggesting that multivitamin use may actually shorten women’s lives. To quote the editor: “Because commonly used vitamin and mineral supplements have no known benefit on mortality rate and have been shown to confer risk….A better investment in health would be eating more fruits and vegetables…”

Image Credit: United States Navy ID 110429-F-NJ219-021 / Wikimedia Commons

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