Ideally, we'd all eat super healthful diets. But that's not the world we live in, and multivitamins may help bridge the nutritional gaps. Jasper White/Getty Images hide caption

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Though some people might need more of specific vitamins, multivitamins don't help most people, studies say. iStockphoto hide caption

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If only it was as simple as popping a supplement and being set for life. But alas, no. iStockphoto.com hide caption

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Ads often tout dietary supplements and vitamins as "natural" remedies. But studies show megadoses of some vitamins can actually boost the risk of heart disease and cancer, warns Dr. Paul Offit. iStockphoto.com hide caption

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