Phosphates are an essential aspect of the function of the human body, particularly in the systems relied on in the production of energy, as well as in bone formation. A phosphate is a molecule created by the combination of one phosphorus atom, and four atoms of oxygen, stated in the chemical form PO4. Phosphorus is one of the elements listed in the Periodic Table, and it is a substance well known beyond the processes of human biology as a powerful component in applications as diverse as munitions manufacturing and fertilizers. If consumed in its pure form, phosphorus is highly toxic. Phosphorus is also flammable in the air.

In its phosphate form, phosphorus is a significant presence in the body, comprising approximately 1 lb (0.5 kg) of the total mass of the average adult. Phosphates are present in a wide variety of food groups; it would be highly unlikely that a person consuming a typical balanced diet of carbohydrates, proteins, and fats could ever experience a phosphate deficiency. A healthy adult will have phosphates present in the blood. The phosphates that are most important to human function are adenosine triphosphate (ATP) and calcium phosphate.

ATP is the crucial energy storage and transportation mechanism present in the muscles of the body. ATP is the ultimate fuel produced and consumed in the production of the cellular energy necessary for the contraction of muscles. Adenosine is a product of nucleic acid, an essential building block in cell formation. Nucleic acid is the portion of the cell that contains hereditary and other related information; deoxyribonucleic acid (DNA) is the best known of these nucleic acids. To create ATP, adenosine combines with three phosphate molecules. ATP also has an important role in the synthesis of proteins within the body. The portion of each cell that acts as the powerhouse for the utilization of ATP by way of chemical reaction is the mitochondria.

ATP is used by the cell to produce energy both anaerobically (without the presence of oxygen) and aerobically (with oxygen). The ATP molecules contain very high amounts of energy potential, and the breakdown of the ATP molecule in the mitochondria releases very large amounts of energy relative to the size of the molecule, a characteristic due to the presence of phosphorus in the ATP molecule.

The primary means by which ATP is created within the body is through the processing of glucose, itself a product of the carbohydrates consumed through food. When processed by the body for the production of energy, one glucose molecule will ultimately render two molecules of ATP. Once formed, ATP is replenished and recycled within each cell indefinitely; ATP is a partner to a reversible reaction that involves a series of conversions involving phosphocreatine (creatine phosphate) that are at the hub of the energy production process. The creation and the reduction of ATP is continuous, as ATP is not stored within the cell in the fashion that glucose or fats can be retained for periods of time in the body. ATP and phosphocreatine are a part of an ongoing recycling process that creates and produces approximately one kilogram of ATP per hour within the entire population of cells in the body. For athletes who have higher energy demands than the general population, the consumption of appropriate carbohydrates is one method of ensuring that the ultimate ATP capacity of the body remains intact. Without glucose, the manufacture of ATP will be limited.

Calcium phosphate is the compound that is essential to the formation of the bone cells. An imbalance in the optimal levels of calcium and phosphates will result in an inability of the body to maintain a strong bone structure. Persons with kidney disease are particularly vulnerable to the effects of such an imbalance. When the kidney fails to maintain the healthy ratio of calcium to phosphorus, usually though a shortfall in its release of vitamin D, the compound that permits the absorption of calcium into the bloodstream, phosphate levels with in the blood rise. This increase in phosphates itself initiates a release of a hormone from the parapituitary gland (PTP), which chemically signals the bones to release stored calcium into the bloodstream to restore the balance between calcium and phosphorus. Over time, the release of calcium from the bones to the bloodstream in the disturbed vitamin D/calcium/phosphate balance can lead to osteoporosis, a loss of bone mass and density that causes a irreversible weakening of the bone.

When phosphate levels rise, the condition is commonly treated by extra supplements of vitamin D to ensure proper calcium absorption. High phosphate levels in the bloodstream are also a powerful indicator of the presence of ketones, the byproduct of excessive fat products in the blood, caused by ketoacidosis. This condition is a symptom of type 2 diabetes, the adult-onset version of this disease.

In recent years, there has been significant sports specific research into the effectiveness of phosphates as a training supplement. Research with the compound sodium phosphate, which involved athletes in controlled conditions engaging in a form of phosphate loading, where predetermined amounts were consumed for a number of consecutive days in training for endurance events, suggested, without concluding, that there could be a reduction in the buildup of lactic acid, accompanied by a slight increase in VO2max, the maximum of oxygen the athlete was capable of processing. Given that there are no adverse impacts known in the ingestion of sodium phosphate, the loading practice is, at worst, neutral.

SEE ALSO Dietary supplements; Minerals; Phosphocreatine.