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Calcium

By Shereen Jegtvig, About.com

Updated July 21, 2009

About.com Health's Disease and Condition content is reviewed by our Medical Review Board

Milk

Milk is the best source of calcium.

Photo © Dawn Allyn
Definition: Calcium is a major mineral and is the most abundant mineral in the human body. Most of it is stored in the bones and teeth (about 99%), and the rest is blood, muscles and extracellular fluid.

Calcium is necessary for strong bones and teeth, plus it plays an important role in blood clotting, muscle contraction, hormonal secretion and normal nervous system function.

Your body constantly breaks down and rebuilds your bones to keep them strong. When you're young, your body builds up calcium as fast as it removed it from the bones. But when you get older, your body tends to resorb more calcium than it puts back so you're at a greater risk for osteoporosis.

Daily Requirements

1 to 3 years 500 mg per day
4 to 8 years 800 mg per day
9 to 18 years 1300 mg per day
19 to 50 years 1000 mg per day
51+ years 1200 mg per day

Calcium supplements are often recommended for adult females to help prevent osteoporosis. Calcium supplements are generally safe. However, taking more than 2500 mg per day on a regular basis may lead to hypercalcemia, kidney problems and may impair the absorption of other minerals. Calcium supplements may interact with several medications, so consult your doctor before taking calcium supplements if you are also taking medications.

Calcium is found in dairy products such as milk, cheese, and yogurt, as well as dark green vegetables, whole sardines and calcium-fortified foods. Your body needs vitamin D in order to absorb and use calcium.

Also Known As: calcium carbonate, calcium citrate, calcium malate

Sources:

Dietary Supplement Fact Sheet: Calcium. Office of Dietary Supplements. NIH. Accessed March 27, 2009. http://ods.od.nih.gov/factsheets/calcium.asp.

Dietary Reference Intakes. Food and Nutrition Board. Institute of Medicine. Accessed March 27, 2009. http://www.iom.edu/Object.File/Master/21/372/0.pdf.

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