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The mineral calcium is well-known for its key role in bone health. Calcium also helps maintain heart rhythm, muscle function, and more. Because of its health benefits, calcium is one of the best-selling supplements in the U.S.

Why do people take calcium?

Calcium is crucial in growing new bone and maintaining bone strength. Calcium supplements are standard for treating and preventing osteoporosis -- weak and easily broken bones -- and its precursor, osteopenia.

Calcium is used for many other conditions. It's an ingredient in many antacids. Doctors also use calcium to control high levels of magnesium, phosphorus, and potassium in the blood. There's good evidence that calcium can help prevent or control high blood pressure. It also may reduce PMS symptoms as well as play a role in preventing certain cancers. Calcium with vitamin D, for instance, may help protect against breast cancer in premenopausal women. The data, though, are still inconclusive as to whether it might do the same for postmenopausal women. Calcium also has been looked at for other uses, for example, aiding weight loss. But so far, these studies have been inconclusive.

The people at highest risk of a calcium deficiency are postmenopausal women. Since dairy products are one of the most common sources of calcium, people who are lactose intolerant or vegan are also at increased risk of calcium deficiency.

How much calcium should you take?

The Institute of Medicine has set an adequate intake (AI) for calcium. Getting this amount from diet, with or without supplements, may be enough to keep your bones healthy. Doctors may recommend higher doses.

Category
Calcium: Adequate Intake (AI)
0-6 months 210 mg/day
7-12 months 270 mg/day
1-3 years 700 mg/day
4-8 years 1,000 mg/day
9-18 years 1,300 mg/day
19-50 years 1,000 mg/day
51 years and up 1,200 mg/day (women) 1,000 mg/day (men)

Women who are pregnant or breastfeeding do not need extra calcium beyond the recommendations above.

The tolerable upper intake levels (UL) of a supplement are the highest amount that most people can take safely. For calcium, it's 2,500 mg/day for adults and children over 1 year.

In general, it's best to take calcium supplements with food. For better absorption, don't take more than 500 milligrams at one time. Split up larger doses over the course of the day. For the body to make use of calcium properly, you also need to get enough vitamin D and magnesium.

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