About one-third of Americans take multivitamins on a daily basis. The theory behind them is they help people get their daily allowance of nutrients they might not get from their diets. A new study in the British Medical Journal found that adults who take multivitamins self-reported 30 percent better overall health than people who don’t use them. But they showed no objective health improvements. Now, I’d caution you not to assume the benefits of multivitamins are only in your head. We need more research. But you should try to get your vitamins and minerals from a healthy, balanced diet with plenty of vegetables.