Normal adults adapt to decreased calcium intake by increasing the fraction of dietary calcium absorbed, but absorption is impaired by aging . Several hormones are involved in calcium metabolism. Two protein hormones , parathyroid hormone and calcitonin, and a derivative of Vitamin D act to make sure the body optimally assimilates dietary calcium. A deficincy of calcium results in rickets in children and osteomalacia, both of which display a lack of bone mineralization. Calcium deficiency may also contribute to osteoporosis .
Toxicity is rare except in certain diseases involving vitamin D or the parathyroid gland.
Dietary sources of calcium are mostly from the dairy foods. However, meat, some beans, seafood, tofu, and green leafy vegetables contain substantial amounts of calcium. Phosphorus Phosphorus is present in the body as inorganic phosphate or phosphate esters, and has many biological roles. Like calcium, the active form of vitamin D regulates phosphorus absorption. It is important for carbohydrate metabolism, cell membrane structure, transport processes, muscle function , and energy storage.