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How Do I Know What Kind of Calcium Supplement to Take?

There are many types of calcium supplements on the shelves today. All are equally effective when taken properly.

Avoid supplements sold as "natural sources" of calcium, such as:

These should be avoided especially if your are pregnant. They can be contaminated with hazardous amounts of toxic heavy metals like arsenic and lead. There is no evidence that these products are more effective.

Take a calcium carbonate supplement (whether Tums or something else) with a meal to make sure the acid level of the stomach is all right.

An adequate vitamin D level is required by the body to absorb calcium. The recommended amount of vitamin D for adults is 600 IU/day. For people over 70, the recommended daily amount is 800 IU.

Do not take a vitamin with iron, or an iron supplement, at the same time as your calcium supplement. The two compete for the same binding site in your body, and will reduce absorption. This same logic applies to taking an iron supplement with a glass of milk, since milk is high in calcium.

Another way to determine which supplement to take is to figure out how much calcium you are getting from your regular diet and then choose a supplement that will raise that level to the recommended daily calcium intake.

You should not take your entire amount of calcium all at once. For instance, you should not take 2 calcium tablets at the same time, or take several Tums with a tall glass of milk. Spread out the doses to improve absorption-probably no more than 500 mg at a time.

Caution: If you have a history of kidney stones, you should definitely talk to your doctor before taking a supplement. Taking supplements is not risk-free.

The best advice is to get as much calcium as possible from your diet, supplement as needed, and exercise regularly.

The development of this topic was funded in part by the Ohio Department of Health.

For more information:

Go to the Osteoporosis health topic, where you can:

Last Reviewed: Aug 27, 2013

Formely, Professor, Clinical Obstetrics & Gynecology
College of Medicine
University of Cincinnati

Senior Instructor of Nutrition
School of Medicine
Case Western Reserve University

Formerly Associate Professor of Clinical Obstetrics and Gynecology
Director, Medical Student Education
No longer associated