Dietary calcium is a major mineral and it's the most abundant mineral in the human body. Most of it is stored in the bones and teeth (about 99 percent), and the rest is in your 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 reabsorb more calcium than it puts back, so you're at a greater risk for osteoporosis.
Ages 1 - 3: 700 milligrams per day
Ages 4-8: 1,000 milligrams per day
Ages 9-18: 1,300 milligrams per day
Men ages 19-70: 1,000 milligrams per day
Women ages 19-50: 1,000 milligrams per day
Women ages 51 and older: 1,200 milligrams per day
Men ages 71 and older: 1,200 milligrams per day
Calcium supplements are often recommended for adult females to help prevent osteoporosis. They are generally safe, however, taking more than 2,500 milligrams 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 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. Ovolactovegetarians can get calcium from dairy products. Your body needs vitamin D in order to absorb and use calcium.
National Institutes of Health. Office of Dietary Supplements. "Dietary Supplement Fact Sheet: Calcium." Accessed March 27, 2009. http://ods.od.nih.gov/factsheets/calcium/.
Otten JJ, Hellwig JP, Meyers LD. "Dietary Reference Intakes: The Essential Guide to Nutrient Requirements." IOM, 2006.