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

The main function of phosphorus is in the formation of 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. It is also crucial for the production of ATP, a molecule the body uses to store energy.

Phosphorus works with the B vitamins. 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 main food sources are the protein food groups of meat and milk. A meal plan that provides adequate amounts of calcium and protein also provides an adequate amount of phosphorus.

Although whole-grain breads and cereals contain more phosphorus than cereals and breads made from refined flour, this is a storage form of phosphorus called phytin, which is not absorbed by humans.

Fruits and vegetables contain only small amounts of phosphorus.

There is generally no deficiency of phosphorus because it is so readily available in the food supply.

Excessively high levels of phosphorus in the blood, although rare, can combine with calcium to form deposits in soft tissues such as muscle. High levels of phosphorus in blood only occur in people with severe kidney disease or severe dysfunction of their calcium regulation.

According to Institute of Medicine recommendations, the recommended dietary intakes of phosphorus are as follows:

• 0 to 6 months: 100 milligrams per day (mg/day)
• 7 to 12 months: 275 mg/day
• 1 to 3 years: 460 mg/day
• 4 to 8 years: 500 mg/day
• 9 to 18 years: 1,250 mg
• Adults: 700 mg/day
• Pregnant or lactating women:
  • Younger than 18: 1,250 mg/day
  • Older than 18: 700 mg/day

Yu ASL. Disorders of magnesium and phosphorus. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 120.

Rakel D, ed. Integrative Medicine. 2nd ed. Philadelphia, Pa: Saunders Elsevier; 2007.

Institute of Medicine. Food and Nutrition Board. Dietary Reference Intakes for Calcium, Phosphorous, Magnesium, Vitamin D, and Fluoride. National Academy Press, Washington, DC, 1997.