Phosphorus as Mineral – Rich Food Sources, Functions, Deficiency & Daily Requirements for Children, Men & Women

PHOSPHORUS (P)

Total body phosphate weighs about 1 kg, 80% of which is present in bone and teeth while 10% is in muscles.

Sources:

• Cheese, milk, nuts, eggs, etc.

Daily requirement:

• Adults : 500 mg
• Pregnant women : 1 gm
• Children: 400 –600 mg. Serum level 0.8-5.1mmol/L.

Absorption:

• Absorption of phosphate is stimulated by parathormone (PTH) and vitamin D3. The absorption is mainly from jejunum.

Functions:

• Phosphate is an important constituent of bones and teeth.
• It is needed for the production of high-energy phosphates such as ATP, CTP, GTP and creatinine phosphate.
• DNA and RNA have phosphate diester linkages that form the backbone of the structure.
• Certain enzymes are activated by phosphorylation
• Phospholipids, phosphoproteins, lipoproteins, nucleotides contain phosphate as one of their components.

Regulation of calcium and phosphorus:

Regulation depends on:

• Vitamin D. Intestinal absorption of calcium and phosphorus is increased by vitamin D. It promotes mineral deposition in bones and phosphate reabsorption in kidneys.
• Calcitonin. It lowers serum calcium and phosphorus. It reduces mobilization from bones.
• PTH increases serum calcium and lowers phosphorus.
• Calcium: Phosphorus ratio is important. There is reciprocal relationship between serum calcium and phosphorus. Rise in calcium or phosphorus is accompanied by fall in the other ion.
• Estrogens and testosterone promote retention and deposition of calcium in bones.
• In women, osteoporosis in which, delayed recovery from fractures are observed after menopause.
• Serum level of phosphate required by adults is 3-4 mg/day, while normal children require 5-6 mg/day.

Clinical manifestations:

• Deficiency of phosphorus results in osteomalacia, renal rickets and cardiac arrhythmia.

Hyperphosphataemia:

It is observed in:

• Diabetes mellitus, starvation
• Renal insufficiency
• Hypothyroidism
• Hypervitaminosis D

Hypophosphataemia:

It is seen in:

• Rickets
• Fanconi’s syndrome 
• Intake of drugs such as antacids

Applied aspects:

• The whole blood phosphate is about 40 mg / dl.
• RBCs and WBCs contain a lot of phosphate.
• Hemolysis should be prevented when blood is taken for phosphate estimation.       

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