If your eating habits are stellar—you consume a wide variety of foods from all food groups, including whole grains, protein sources like lean meat, poultry, or fish, low-fat dairy products and nine servings of fruits and veggies daily—you may not need a vitamin. When it comes to getting nutrients, "food first" is the best course of action. "That's because foods contain important components that you don't always get in a pill, such as disease-fighting phytochemicals," says Rosalyn Franta Kulik, R.D., author of the American Dietetic Association position paper on fortification and nutritional supplements. Real health benefits, such as lower cancer risk and stronger bones, probably come from elements in foods working together—such as calcium interacting with protein in milk, or vitamin C and folate with the fiber in broccoli. In a recent study, postmenopausal women who got most of their calcium from foods had higher bone density than those who relied on supplements.
But the reality is, between busy schedules and bad choices most people don't eat well every day. The latest government food surveys show we're falling short—especially on magnesium and vitamins A and C found in fruits and vegetables, and vitamin E from nuts and seeds. A multivitamin can pick up some of the slack.
"Taking a multivitamin provides some nutritional insurance," says Paul Coates, Ph.D., director of the National Institutes of Health Office of Dietary Supplements in Bethesda, Maryland. "But it's not a license to eat poorly." A reasonable compromise: Aim for a healthy diet, but pop one vitamin on the days that well-rounded nutrition isn't happening. And rest assured that a basic multi is considered safe—whether or not you really need it.