For years, women have been told to take extra calcium to guard against osteoporosis.

But doctors just reversed that advice. After looking at scores of studies, the U.S. Preventive Services Task Force (USPSTF) says that common doses of calcium and vitamin D don't prevent fractures in women past menopause who have healthy bones, and they may raise the risk of kidney stones.

That recommendation comes on the heels of two new studies showing that men and women with high calcium levels from supplements were more likely to die of heart disease than those who got less calcium or who got their calcium from diet alone.

Calcium is just the latest supplement to falter under scientific scrutiny. Other studies have questioned the value of fish oil, and antioxidants like vitamins C, E, and beta-carotene.

Does that mean you should ditch your daily calcium pill? What about other kinds of supplements?

Experts on both sides of the debate say that despite discouraging headlines, it's still smart for some people to take supplements, depending on their individual nutritional needs.

"I think scientists are still trying to make sense of it all, particularly the latest calcium studies. In many cases the risks don't appear to apply to all people," says Carol Haggans, a registered dietitian who keeps up with the latest research for the Office of Dietary Supplements at the National Institutes of Health.

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