Approximately 700 g of phosphorus exists in adult tissues, and about 85% is present in the skeleton and teeth as calcium phosphate crystals. The remaining 15% exists in the metabolically active pool in every cell in the body and in extracellular fluid compartment.
In older adults serum phosphate concentrations are typically lower, hypophosphatemia (<2.5 mg/dl) may be more common among older adults. Normal blood concentrations in infants are higher. Health conditions such as diabetes, starvation, and alcoholism can cause levels of phosphorus in the body to fall. The same is true of conditions that make it hard for people to absorb nutrients, such as Crohn's disease and celiac disease.
Phosphorus helps filter out waste in the kidneys and plays an essential role in how the body stores and uses energy. It also helps reduce muscle pain after a hard workout. Phosphorus is needed for the growth, maintenance, and repair of all tissues and cells, and for the production of the genetic building blocks, DNA and RNA. Phosphorus is also needed to help balance and use other vitamins and minerals, including vitamin D, iodine, magnesium, and zinc.
Nutritionists recommend a balance of calcium and phosphorus in the diet. The typical Western diet, however, contains roughly 2 - 4 times more phosphorus than calcium. Meat and poultry contain 10 - 20 times as much phosphorus as calcium, and carbonated beverages such as colas have as much as 500 mg of phosphorus in one serving. When there is more phosphorus than calcium in the body, the body will use calcium stored in bones. This can cause osteoporosis (brittle bones) and lead to gum and teeth problems. A balance of dietary calcium and phosphorus can lower the risk of osteoporosis.
Dietary reference intake
Infants 100-300 mg/day
Children 500 mg/day
Adolescents 1250 mg/day
Adults 700 mg/day
Pregnant 700-1250 mg/day
Lactating 700-1250 mg/day
Phosphorus content of selected foods
Pancakes, 2 (476 mg)
Cottage cheese, 1 cup (341 mg)
Pasta with cheese, 1 cup (322 mg)
Baked beans, 1 cup (293 mg)
Sole, 1/2 fillet (246 mg)
Milk, 2% fat, 1 cup (232 mg)
Ham, 3 oz (210 mg)
Beef, ground, cooked, 3 oz (165 mg)
Cheddar cheese, 1 oz (146 mg)
Shrimp, boiled, 2 large (137 mg)
Mixed nuts, 1 oz (123 mg)
Tofu, regular, ½ cup (120 mg)
Potato, baked, with skin, 1 (115 mg)
Egg, 1 (96 mg)
Bread, whole wheat, 1 slice (65 mg)
Loss of appetite
In children – decreased growth