Phosphorus is a mineral that makes up 1% of the total body weight. It is present in every cell of the body, but 85% of the body's phosphorus is found in the bones and teeth.

The main food sources are the protein food groups of meat and milk (also lentils, seeds, beans, nuts, chocolate, peanut butterand bran). A meal plan that provides adequate amounts of calcium and protein also provides an adequate amount of phosphorus.

Whole-grain breads and cereals contain more phosphorus than refined cereals and breads made from refined flour. However, the phosphorus in whole-grain products is in the form of phytin, a storage form of phosphorus that is not absorbed by humans well.

Fruits and vegetables contain only small amounts of phosphorus.

The main function of phosphorus is in the formation of the bones and teeth. It plays an important role in the body's utilization of carbohydrates and fats, and in the synthesis of protein for the growth, maintenance, and repair of cells and tissues.

Phosphorus works with the B vitamins in their functions in the body. It also assists in the contraction of muscles, in the functioning of kidneys, in maintaining the regularity of the heartbeat, and in nerve conduction.

The recommended allowances of intake of phosphorus are:
Birth-3 years: 300-800mg
4-10 years: 800mg
Adults, men and women: 800-1200mg
Pregnancy/lactating women: 1200mg
Most diets in the U.S. have adequate amounts of phosphorus. There is no known deficiency of phosphorus because it is so available in the food supply.

Excessively high levels of phosphorus in the blood, although rare, can combine with calcium and deposit in soft tissues like muscle. These high levels of phosphorus in blood only occur in people with severe kidney disease or severe dysfunction of their calcium regulation.