While supplements can help us fill in some of the gaps in our daily diet, Bob's issue is that they're often sold as one-size-fits-all problem solvers. He uses women's multivitamins with folic acid as an example. "Folic acid at RDA levels is a must for women who are pregnant or planning to have children soon," says Bob, "But it's looking as if half that amount in a multivitamin might be right for women who are past that point in their lives—or for men." Some studies have even suggested a link between an excess of folic acid and cancer.
Do: Take supplements created for your age, health needs and lifestyle, and check the labels. With a few exceptions (such as vitamins C, E and B12), Bob recommends that most daily value levels shouldn't exceed 100 percent (his own line of multis for adults over 50 contains folic acid at 50 percent of the RDA).