Taking multivitamins is a pointless waste of time and money, with no credible evidence at all to support the hopeful claims made about them, something that the Food & Health Skeptic has reminded us of again and again.
But by the same token, this study linking multivitamins to breast cancer is the same kind of epidemiological rubbish that supplies so many of the so-called "studies" supporting their use.
And it is the same kind of pseudo-scientific junk that produces the endless round of red wine is good for you, red wine is bad for you, no it's good you etc etc stories that appear with monotonous regularity in the media.
About the only use these studies have is a pointer towards what should be investigated using the only method that actually means anything and which produces results that are real evidence, ie the properly randomised double-blind trial.
Anything else is just speculation about possible causal effects and it would be better if these were not reported in the media (and not fed to the media by publicity seeking researchers or institutions).
Dr Ray comments:
Another nasty one for the health freaks. The absolute risk involved is small but such weak effects underpin most dietary advice.The study is utter rubbish anyway. 1). It's based on self-reports; 2). It commits the "correlation is causation" fallacy. WHY were some women taking supplements? Probably because they felt less healthy anyway. The abstract is here. The title of the article is "Multivitamin use and breast cancer incidence in a prospective cohort of Swedish women"
While it may not do any good, the most likely thing that can be said about taking multivitamins is that it is nothing more than harmless self-dosing.