They claim to help you sleep, make your hair grow, speed weight loss, improve your sex life and ward off the nasty cold going around the office. Though it's often impossible to tell if dietary supplements work, consumers generally feel certain they can't hurt.

But they can.

The Food and Drug Administration has identified hundreds of supplements tainted with pharmaceuticals – from antidepressants and erectile dysfunction to weight-loss drugs – since 2007, a study published Friday shows. Even after FDA tests proved the supplements contained unapproved or recalled medications, many of the products continued to be marketed and sold, the analysis finds.

The report in JAMA Network Open calls into question the FDA's ability to effectively police the $35-billion-a-year supplements industry.

Photo: Courtesy of FDA Flickr

Source: NPR

The vinegar test Today I learned that since vitamins and supplements aren't regulated by the FDA, they can have a bioavailability of anywhere from 0-100%. For anyone who isn't a huge medical nerd, bioavailability is how much of a substance that you ingest actually makes it into your bloodstream. Since some vitamins have a bioavailability of zero, that means that the pill does absolutely nothing for you and you're basically paying to poop out a pill. But if the FDA isn't going to require a specific bioavailability, how do we know which vitamins will actually work?? According to one of the doctors who teaches us, he has his patients who want/need to take vitamins or supplements do a very simple test that he calls the vinegar test. Just pour some vinegar in a cup, put your pill in it, wait 30 minutes, and see if it dissolves. Vinegar is acidic like your stomach acid, so if the pill dissolves, it's very likely that the contents of that pill will reach your blood. Here you can see that I did it with my multivitamin and my calcium/vitamin D supplement. This worked because the calcium broke down almost immediately and the multivitamin took about 5 minutes, but I would recommend doing this in separate cups if you have multiple pills to make sure you can see which ones break down.