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Expert Opinions

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My calcium supplements list two numbers on the label, one for total weight and the other for elemental calcium. Which number should I use?

R.G., via WholeHealthMD.com



According to Bess Dawson-Hughes, M.D., professor of medicine at Tufts University in Boston and an expert on calcium, the amount of elemental calcium tells you how much of your supplement is actually calcium.

"For example, with calcium carbonate, 40% of the total weight is calcium, and 60% is carbonate," she explains. This means that a 1,000 mg tablet of calcium carbonate provides 400 mg of elemental calcium. Calcium citrate, another commonly sold form, is about 20% elemental calcium.

Most supplements don't bother stating the total weight and say calcium when they really mean elemental calcium. But some supplements list amounts for both total weight and elemental calcium.

"The confusion begins when people know they need to get 1,200 mg of calcium but use the wrong number and end up getting less calcium than they need," says Dr. Dawson-Hughes. Women of all ages and men over age 50 should be getting at least 1,200 mg of calcium (elemental calcium, that is) a day. Examine supplement labels carefully and make sure you know what you're getting.

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