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Phosphorus
Description:
Next to calcium, phosphorus is the second most abundant mineral in the body, making up about 1% of your body weight.
Method of Action:
Phosphorus is most abundantly seen in the body as a constituent of the molecule phosphate, one of the bone salts which add structural rigidity to the softer protein matrix of bone and teeth.
Perhaps phosphorus’ most important metabolic role is as a constituent of the molecule phosphate. When this molecule links to an adenosine pyrophosphoric acid (ADP) molecule adenosine triphosphate (ATP) is formed, processing a high energy phosphate bond. When broken, this bond releases energy and the phosphate, reforming and ADP molecule. The ATP "energy" molecule is formed during glycolysis and other processes involving the release of chemical energy from food. ATP is used as the primary source of energy for many metabolic and enzymatic activities, especially muscle contraction, active transport, and the formation of DNA. Phosphate is an important constituent of RNA and DNA. It serves to link the individual bases with one another.
The energy released from the high energy phosphate bond of ATP is essential for the operation of the sodium/potassium pump, which exchanges three sodium ions for two potassium ions across a biological membrane. This pump is used to regulate relative amounts of sodium and potassium excreted and retained in the body.
Phosphate, from ATP, reacts with choline to initiate synthesis of phospholipids which are essential constituents of cell membranes. Phospholipids are instrumental in regulating cellular permeability and are found in the exterior membrane of nerve cells. They are also helpful in solubilizing relatively nonsoluble triglycerides and cholesterols.
ADP, which contains two phosphate molecules, is a constituent of blood platelets and is secreted from platelet granules to stimulate platelet aggregation for blood clotting.
Phosphate also plays an important role, due to its effective buffering action, in maintaining acid/base balance in blood plasma.
Phosphorus absorption is about 50-70% efficient, as calcium, iron, and zinc tend to complex with phosphorus in the stomach, thus reducing absorption. Vitamin D tends to promote the absorption of both phosphorus and calcium from the intestine. Excretion through the urine regulated the body’s level of phosphorus.
Properties & Uses:
Phosphorus supplementation is important in patients with low phosphate to calcium ratios for promotion of proper bone and tooth mineralization, especially in younger persons.
Phosphorus may also be beneficial in reversing, to some extent, osteomalacia, rickets, bone pain, and muscle weakness experienced by persons with hypophosphatemia.
Toxicity Levels:
Phosphorus is not toxic in large amounts, although a disproportionately large amount of phosphorus relative to calcium can induce an increased fecal excretion of calcium, possibly resulting in a calcium deficiency.
In patients with renal insufficiencies, there may be a decreased urinary excretion of phosphorus, resulting in high blood phosphate levels. This condition may result in skeletal demineralization and mineral resorption. This condition can be controlled by ingestion of aluminum hydroxide or calcium carbonate, both of which reduce phosphate absorption.
Recommended Dietary Allowances:
RDA for adults 800 - 1,200 mg
RDA for child/adolescent 800 mg
RDA for infants 240 - 400 mg
RDA for pregnancy 1,200 mg
RDA for lactation 1,200 mg
Food Sources:
Almonds, beans, calf liver, cheese, eggs, fish, legumes, milk products, peanuts, peas, poultry, pumpkin seeds, red meat, scallops, soybeans, sunflower seeds, tuna, whole grain products.
Deficiency Symptoms:
Phosphorus is found so abundantly in plant and animal foods that deficiency is unlikely. Excess vomiting or consumption of aluminum hydroxide, found in some antacids and anticonvulsant medications, may lead to phosphorus deficiency. Symptoms include bone pain, loss of appetite, weakness and brittle bones.