An estimated 85,000 supplement products are sold in stores and online. Most of these are vitamins and minerals which, though unlikely to offer real health benefits, are fairly harmless. The supplement industry — which rakes in some $32 billion a year from American consumers — claims that the vast majority of supplements are safe. But that’s really an impossible claim, because most supplements don’t go through any kind of rigorous scientific scrutiny.

Unlike prescription drugs, dietary supplements do not have to be approved by the Food and Drug Administration (FDA) before they’re sold. That means that the public typically finds out about a product’s risks thanks to anecdotal reports from patients and doctors like Cohen.

Cohen’s experience with his patients