Nearly 99 percent of your body's calcium supply is present in your bones and teeth. Most of it is integrated into the osseous tissue, which keeps your bones strong and protects against fractures from everyday activities. However, a small, but important portion of it is reserved for exchange with the blood stream, which transfers this essential nutrient to other organs. Calcium enables your muscles, nerves and hormones to function properly; regulates blood clotting and blood pressure; keeps the heart beating; and enables you to absorb and metabolize other vitamins and minerals, such as iron and B12. The majority of the calcium that enables these function comes from your bones.
Calcium is incomplete without phosphorus. Together, the minerals form hydroxyapatite ([Ca10(OH)2(PO4)6), which is the major component of bones and teeth. People who lack or cannot absorb adequate amounts of phosphorus will experience decreased bone mass, even if they consume the recommended daily allotment of calcium. On the other hand, if a person has too much phosphorus in his blood, his body will draw calcium from his bones to bond with it, thereby also decreasing bone strength. Because of this delicate balance, calcium and phosphorus are called co-dependent minerals.
The recommended daily intake for calcium is 1,000 mg for men 19 to 70 and 1,200 mg for men 71 and older. Because of the increased risk of osteoporosis in older women, they should begin consuming 1,200 mg at age 51. This mineral is found in milk products, green leafy vegetables, legumes, seeds, lentils and fish that are eaten with their bones, such as canned sardines. The recommended daily intake of phosphorus for all adults is 700 mg, which can be obtained from milk, grains, sweet potatoes, spinach, nuts and meats.
A deficiency or imbalance of calcium and phosphorus can result in bone diseases, such as osteopenia and osteoporosis. Osteopenia is a loss of bone mass, which can lead to osteoporosis, where the skeleton begins to degenerate. Both of these diseases are more common in women over 50, but can occur anytime there is a prolonged mineral deficiency.