Are Nutrional Supplements Bad For You?

October 14, 2011

Medicine, DrugsEvery so often an opinion piece circulates citing a research paper that posits that nutritional supplements, and multivitamins in particular, are more detrimental than helpful. Looking directly at the research being cited in this current round of nutritional supplement defamation, it seems to be no more than a sensational headline.

The first study claimed to find that among about 40,000 older woman surveyed, there was an increased risk of mortality for those taking supplements.

However: multivitamin use was self-reported. Their results were based on “multivariable adjusted proportional hazards regression models” which I hope means they attempted to control for the fact that people who take multivitamins are more likely to already have health concerns.

There was a study a few years ago that this reminds me of: it claimed to find that athletes who stretched were more likely to injure themselves, but it didn’t control for quantity of exercise. A professional athlete who stretches, but works everyday to push their body to the limit, is of course far more likely to injure themselves compared to a casual exerciser who doesn’t stretch. That doesn’t mean there’s a causality between stretching and injury, just like I wonder how well they controlled for existing/anticipated illness and multivitamin use (i.e. “my mother had bad health issues, I better be proactive and take a nutritional supplement”).

A second study found that, when looking at 68 different randomized trials (as opposed to self-reported use), “there was no significant effect on mortality”. The more you add controls (blind, randomized studies with follow-ups), the less correlation there seems to be.

So avoid the attention grabbing headlines, and make nutritional supplement decisions based on your personal needs, history, and family health. Take to a nutritionist, a naturopath, and/or your family doctor.

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