Vitamin supplements and risk homeostasis


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Just when I thought I’d extricated myself from the great “bike helmets and risk homeostasis” debate, along comes a study suggesting that taking multivitamin pills causes people to behave in less healthy ways for the rest of the day. Even worse, the title of the paper in Psychological Science (“Ironic Effects of Dietary Supplementation: Illusory Invulnerability Created by Taking Dietary Supplements Licenses Health-risk Behaviors”) is likely to start an even fiercer debate about the correct use of the word “irony.” (Maybe it’s just a pun, since some multivitamins contain iron.)

But seriously, folks… The researchers gave a bunch of volunteers a harmless placebo pill; half of them were told it was a placebo, while the other half were told it was a multivitamin. Then they did some experiments and found that those who thought they’d taken a multivitamin “expressed less desire to engage in exercise and more desire to engage in hedonic activities, preferred a buffet over an organic meal, and walked less to benefit their health than the control group.”

It would be silly to take this study as evidence that multivitamins are “bad.” Still, I can’t help feeling that it does point toward a trade-off that people may unconsciously make when they look for “exercise pills” and other shortcuts. Most of the athletes I know take multivitamins as a way of “covering their bases” in case their diet falls short — as, in the real world, it occasionally will. But are there times when it only falls short because they feel that it’s okay to cut corners because they’ve got the pills as back-up? That’s what this study suggests. Maybe it’s better to take away the safety net, so you have more motivation to stay on top of your diet.

8 Replies to “Vitamin supplements and risk homeostasis”

  1. Guilty of the second paragraph. I read an article 5 years ago that studied male athletes and stated they were more prone to rely on vitamins and power bars. I did.
    My wife got me to plant a garden, cook and eat properly and lets me use my recovery bars for recovery. But I would live on clif bars, recovery bars and vitamins if I could. But now, I would not give up my home made pizza, pasta, and pesto.

  2. Wow.

    A few months ago you mentioned a study that found that openly administered placebos still work.

    Apparently they don´t induce people riskier behaviour, so taking placebo’s is actually healthier than taking vitamin supplements 🙂

  3. @RH YOu just need to know you are taking placebo. Otherwise you it works contra-effective: you eat on healthier (cause you think you will have a real pill) and you have no safety-backupp.. Should be a good marketing stund: Buy know 3 for the price of 2 non working placebo’s, that actually keep your behaviour the same as it is. Just 50 dollar/ piece.

    I have been reading this before in some psychology magazines, and remember I had some talks about it with fellow students, who lit said ‘Oh, but I can back upp with the multi vit’.

  4. As someone said on Twitter, the real test will be to find out what happens if you wear a bike helmet AND take a multivitamin (and whether it makes any difference if you know it’s a bike helmet). 🙂

  5. Athletes engage in poor eating and drinking habits after events, too, why b/c they think the excercise they just did risk homeostasis. Just think you were at the Scotiabank Toronto Waterfront Marathon this past weekend. How many engaged in poor eating (ie Burgers, buffets) or drinking ie alcohol after the events.

  6. That’s true. But there’s a difference: training for and running an endurance race has quantifiable health benefits. Sure, these benefits may sometimes be cancelled out by post-run celebrations. At worst, you end up back where you started. With vitamin supplements, on the other hand, most evidence suggests that they offer NO benefits — so if you then allow yourself to “compensate” with some poor health decisions, you end up worse off than you started.

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