Several large-scale studies have made it clear that our well-intentioned attempts to eat the best of everything have begun to backfire. For example, women who take a multivitamin and eat fortified foods are often getting too much vitamin A. Many of us look for 100 percent of the DV for A in our multi because it's frequently praised for having immune-boosting antioxidant powers. But if you take that multi at breakfast with a bowl of fortified cereal and milk, you're likely to ingest more than your daily vitamin A requirement before you step out the door. Even small excesses of A have been linked to an increased risk of birth defects, liver problems, and nervous system disorders, as well as long-term bone damage that can eventually lead to hip fractures.