Calcium and phosphorus are essential nutrients that must be obtained from the diet. Both elements are important for the formation of teeth and bone structure. A calcium-phosphate compound, hydroxyapetite, also known as bone mineral, makes teeth and bones strong and resistant to breaking. Too little calcium or phosphorus impairs the formation of this compound, causing frail, brittle bones, and leads to osteoporosis. Before taking any dietary supplement, you should always consult with a physician to be certain over-the-counter supplements are compatible with your medications or health conditions.
Biological Functions
In addition to bone formation, calcium is important for many biological activities in your body like muscle contraction and cardiac function. The amount of calcium available in the blood, and its metabolism, is very strictly regulated. Even a relatively small imbalance in your calcium concentration could result in serious problems, like cardiac arrest. In addition to bone formation, phosphorus is important for soft tissue structure, the formation of genetic material and the storage of energy. Phosphate is far less tightly controlled than calcium.
Vitamin D
The major regulatory factor of calcium metabolism and its availability -- homeostasis -- is vitamin D. Calcium homeostasis is tightly maintained by the action of vitamin D on your bones, the small intestine and kidneys. It acts to alter the amount of calcium that is being stored, absorbed and excreted. Although phosphorus is an important factor in the formation of hydroxyapetite, it does not regulate calcium absorption or homeostasis like vitamin D does.
Calcium Homeostasis
Low calcium is called hypocalcemia. When blood calcium is low a hormonelike form of vitamin D alters the breakdown and release of calcium from your bone minerals, increases dietary calcium absorption in your small intestine and decreases calcium excretion in your kidneys. These actions cause the calcium level in your bloodstream to rise back to normal, preventing severe hypocalcemia. High blood calcium, hypercalcemia, signals the body to store calcium as bone mineral, absorb less calcium in the small intestine and increase the kidney's excretion of calcium. These actions decrease calcium availability in the attempt to maintain calcium homeostasis.
Recommended Amounts
Phosphorus is highly available in the diet. With the exception of rare circumstances, phosphorus intake is typically sufficient when your protein and calorie needs are being met. Due to a decline in consumption of calcium-rich foods and drinks and an increase in other types of sweetened beverages, calcium deficiency is more likely to occur. The Institute of Medicine suggests children ages 1 to 3 should get an average of 500 milligrams of calcium per day, with an increase to 800 milligrams daily for children ages 4 to 8. Adolescents need slightly more calcium: 1,300 milligrams per day. Women 19 through 50 years old and men up to 71 require on average 800 milligrams daily. Women over 50 and men 71 and older should take 1,000 milligrams per day to ensure strong, healthy bones and teeth.
References
- Institute of Medicine -- Report Brief: Dietary Reference Intakes for Calcium and Vitamin D
- "Blood Purification"; Calcium and Phosphorus Homeostasis; Jeremy G. Taylor, et al.; March 2009
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