We all make those "to better health" resolutions at the turn of every year. But if taking vitamins is on your list, you might want to think twice. New studies published in Annals of Internal Medicine show that if you're eating a balanced diet, taking a daily multivitamin does not help prevent chronic health problems. There are some exceptions, of course, like people who have dietary restrictions or women who are pregnant. But if you can help it, your best bet is a good old-fashioned healthy lifestyle—not a wonder pill.