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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.

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.


Can you get calcium naturally from foods?

Good sources of calcium include:

  • Milk
  • Cheese
  • Yogurt
  • Broccoli, kale, and Chinese cabbage
  • Fortified cereals, juices, soy products, and other foods
  • Tofu

Experts say that most adults in the U.S. don't get enough calcium. While improving one's diet will help, many people do need to take calcium supplements as well.

What are the risks of taking calcium?

  • Side effects. At normal doses, calcium supplements may cause bloating, gas, and constipation. Very high doses of calcium can cause kidney stones. Research has found an increased risk of heart attacks and strokes in some people taking calcium supplements in addition to a diet high in calcium, though the true accuracy of these findings is being actively debated by experts.
  • Interactions. If you take any prescription or over-the-counter medicines regularly, ask your doctor if it's safe to use calcium supplements. Calcium can interact with drugs for heart disease, diabetes, epilepsy, and other conditions. Excessive doses of vitamin D can result in dangerously high levels of calcium. High doses of calcium can also interfere with the absorption of other minerals, like iron and zinc. In general, take calcium one to two hours apart from other supplements or medications. When taken at the same time, calcium can bind those products and pass them unabsorbed from the body.
  • Risks. People with kidney disease, heart problems, sarcoidosis, or bone tumors should not take calcium supplements unless their doctors suggest it.
  • Overdose. Excessive levels of calcium in the blood can cause nausea, dry mouth, abdominal pain, irregular heartbeat, confusion, and even death.

There is no need to use products identified as "coral calcium." Claims made that coral calcium is superior to regular calcium are unsubstantiated. Also, coral calcium products may contain dangerous amounts of lead.

WebMD Medical Reference Reviewed by David Kiefer, MD on November 02, 2014



Longe JL ed, The Gale Encyclopedia of Alternative Medicine, second edition, 2004.

Office of Dietary Supplements web site: "Calcium."

Natural Marketing Institute's 2007 Health & Wellness Trends Database.

Natural Standard Patient Monograph, "Calcium."

WebMD Feature: "Boning up on Calcium: Supplements for Bone Health."

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