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You lack supplement savvy

More is not better when it comes to vitamins and supplements, and too much of a good thing can actually be harmful.

In 2011, an analysis of data on nearly 40,000 women found that those who took dietary supplements—especially iron—were actually at slightly higher risk of dying, although the investigators weren't sure why. "There's no really long-term studies that show unequivocal benefits of taking vitamin and mineral supplements," says Dr. Rogg. "If you're going to take supplements, take them in moderation, and stick to the recommended daily doses."

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