Phosphorus (chemical symbol P) is a chemical element discovered by the German alchemist Hennig Brand in 1669. It plays an essential part in multiple biochemical reactions for both plants and animals and is essential to all life. Phosphorus is found in living things and in soil and rock, mostly as chemical compounds known as phosphates. Rock and soil phosphorus are mined extensively throughout the world, but especially in the People’s Republic of China and the United States.
Elemental phosphorus exists in a number of allotropic forms, primarily white, red, and black phosphorus. Allotropes are forms of an element with differing physical and chemical properties. White (also called yellow or common) phosphorus is a wax-like substance formed by heating phosphorus until it vaporizes and the condensate solidifies. One of this form’s characteristics has given the English language the adjective phosphorescent, from white phosphorus’s tendency to glow in the dark when exposed to air.
White phosphorus is highly toxic, causes burns if it comes in contact with skin, and is so combustible that it has to be stored underwater for safety. Red phosphorus is a rust-colored powder created by heating white phosphorus and exposing it to sunlight. It is not as combustible as the white form. Black phosphorus is made by heating white phosphorus under extremely high pressure until it resembles graphite. In plants, phosphorus is necessary for photosynthesis to take place. In the human body, phosphorus works in tandem with another element, calcium, in much the same way that two other electrolyte components, sodium and potassium, do. Though phosphorus is found in every cell of the human body and accounts for 1% of the body’s total weight, its primary function is working in conjunction with calcium to form teeth and bones.
Eighty-five percent of the phosphorus found in the body is located in these structures. In a delicately balanced chemical reaction, parathyroid hormone (PTH), calcitonin, and 25-dihydroxy vitamin D regulate the absorption of both calcium and phosphorus from the intestinal tract, thus making it available for the production of bones and teeth. If an excessive amount of phosphorus is absorbed, the phosphorus combines with all available calcium and prevents the calcium’s efficient use in making and maintaining bones and teeth. PTH balances the proportions of calcium and phosphorus in the body by increasing the release of calcium and phosphate from bone and the loss of phosphorus via the kidneys while limiting the excretion of calcium. PTH also increases the activity of the 25-Dihydroxy v25-Dihydroxy vitamin D, which, in contrast, increases the absorption of both phosphorus and calcium from the intestinal tract.
Compounds of phosphorus are used to make fertilizers, detergents, and water softeners. They are also used in the manufacture of steel, plastics, insecticides, medical drugs, and animal feeds. Phosphorus is used in the manufacture of safety matches and pesticides, including rat poison.
Phosphorus found in the blood stream and in soft tissue has a highly significant role to play in a variety of body functions. Working with vitamin B, phosphorus is involved in the metabolism of fats and carbohydrates, in both the repair of damaged cells and tissues and the routine maintenance of healthy ones. Phosphorus is necessary for the regularity of the heartbeat and aids in the contraction of all other muscles throughout the body. Phosphorus is needed for the functioning of the kidneys and plays a part in the conduction of impulses along the network that makes up the nervous system.
According to the American Dietetic Association, phosphorus intake in the United States is generally above what is needed. Therefore, under normal circumstances with normal food intake, there is seldom if ever a need to supplement intake of phosphorus. Persons suffering from eating disorders such as anorexia and bulimia can be deficient in phosphorus intake as
well as other nutrients. As the best source of phosphorus is in protein foods such as meat, eggs, and milk products. Some vegetarians may also need to evaluate their intake of this element. Excess consumption of processed foods, inadequate intake of whole foods, and fertilizers and pesticides are some of the causes for excess phosphorus.
Beside high-protein foods, phosphorus is also found in decreasing quantities in wholegrain breads and cereals, especially unprocessed ones, and in minute amounts in fruits and vegetables. The phosphorus present in wholegrain breads and cereals, however, exists as a substance called phytin. Phytin combines with calcium to create a salt that the human body is incapable of absorbing, thus making grains that are unprocessed and not enriched a negligible source of phosphorus. But both commercially prepared cereals and breads may provide this element as they are frequently enriched with it. Phosphates can also be taken by mouth as a tablet.
White phosphorus is poisonous. Red phosphorus is not. As noted, white phosphorus is a highly toxic, flammable substance capable of burning the skin on contact, and of igniting at room temperature. It should be handled with extreme care. Accidental phosphorus poisoning can happen from both fertilizers and pesticides.
Humans rarely come into contact with elemental phosphorus, so these precautions apply primarily to workers in the phosphorus industry. Phosphates sometimes are leached into water systems through sewage
and can drastically alter the chemical makeup of lakes and rivers. In sufficient quantities, they can lead to the death of nearly all forms of aquatic life.
A normal blood serum level of phosphorus is 2.4–4.1 mg per deciliter of blood. An abnormal serum phosphorus level should be evaluated by a physician. Phosphorus levels higher than normal can indicate a diet that includes an excessive phosphorus intake, inadequate intake of calcium, or lack of PTH (parathyroid hormone) in the system. It can be related to bone metastasis associated with cancer, liver or kidney disease, or sarcoidosis.
Serum phosphorus levels that are below normal can be related to insufficient phosphorus or vitamin D in one’s diet leading to rickets in children and osteomalacia in adults. Disorders of the parathyroid gland,
causing it to secrete excessive quantities of PTH, or of the pancreas, causing it to secrete too much insulin, also affect blood levels of phosphorus. Diabetic ketoacidosis or too much calcium are other possible causes.
Multiple endocrine neoplasia (MEN) is yet another condition that often is associated with lower than normal levels of phosphorus.
Phosphorus preparations taken to supplement low phosphorus levels in the body can cause diarrhea.
Antacids can decrease the absorption of phosphorus. Laxatives and enemas that contain the chemical compound sodium phosphate and excessive intake of vitamin D can increase phosphorus levels in the body. Administration of intravenous glucose solutions will cause phosphorus to combine with the glucose that is being absorbed by the cells.