Americans spend billions of dollars every year on dietary supplements that claim to promote almost every aspect of our health. But how much do you know about the supplements you’re taking?

A recent government study found that nearly 60 percent of adults take vitamins, minerals, fish oil, herbal capsules, melatonin, probiotics and other types of dietary supplements. While most people used just one or two supplements — multivitamins and vitamin D were the two most popular products — it was not uncommon for people to report using three, four or more supplements at a time.