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.