It can be tough to keep up with dietary trends. Like eating eggs: good for you or bad? But one thing is certain. Taking a multivitamin is a healthy choice. Isn’t it? Not necessarily. Because researchers have found that people who take dietary supplements may make less healthful choices. The work appears in the journal Psychological Science. [Wen-Bin Chiou and Chao-Chin Yang, Ironic Effects of Dietary Supplementation: Illusory Invulnerability Created by Taking Dietary Supplements Licenses Health-risk Behaviors, link to come]

Half the population uses some sort of dietary supplement, and that figure is on the rise. Yet we don’t seem to be getting any healthier. So researchers took a closer look at how people who pop health pills actually behave. One group of volunteers was asked to take a dietary supplement, the other group was told they were getting a placebo. In fact, both groups received dummy pills. But it turns out that subjects who thought they’d taken a supplement made less healthy choices, opting for the buffet instead of an organic meal and walking less than their supplement-deprived pals.

It could be that folks who supplement feel like they’ve already done their duty when it comes to their health. So they’re more likely to indulge. Which suggests that these pills might not make us healthy, and certainly don’t make us smart.