Phosphorus recommended intakes

The recommended ratio of phosphorus to calcium is 1 1, except in infants it is 2 1. For older infants, the recommended intake of phosphorus is increased to 80% of the calcium requirement, so that the ratio is similar to cow s milk (Harper 1969). Both phosphorus and calcium are distributed similarly in foods, hence a sufficient intake of calcium ensures a sufficient intake of phosphorus. The exception is cows milk, which contains more phosphorus than calcium (Harper 1969). The adult daily requirement for phosphorus is about 700 mg. A balanced diet provides sufficient amounts of phosphorus because it is commonly found in foods (phosphoproteins and phospholipids, inorganic phosphate), especially milk and milk products, wheat, meats and fish (Latner 1975). In the body, normal serum (inorganic) phosphorus levels are 4-7 mg/100 mL in children and 3-4.5 mg/100 mL in adults and the elderly. In body fluids and tissues, normal serum phosphorus levels found are 40, 170-250, 360, and 22,600 mg/100 mL in blood, muscle, nerve, and both bones and teeth, respectively (Harper 1969 Tietz 1970). 

Milk is an excellent source of calcium, phosphorus, riboflavin (vitamin B2), thiamine (vitamin Bl) and vitamin B12, and a valuable source of folate, niacin, magnesium and zinc (Food Standards Agency, 2002). In particular, dairy products are an important source of calcium, which is vital for maintaining optimal bone health in humans (Prentice, 2004). The vitamins and minerals it provides are all bioavailable (i.e. available for absorption and use by the body) and thus milk consumption in humans increases the chances of achieving nutritional recommendations for daily vitamins and mineral intake (Bellew et al., 2000). 

Phosphates are important because they affect the absorption of calcium and other elements. The absorption of inorganic phosphorus depends on the amount of calcium, iron, strontium, and aluminum present in the diet. Chapman and Pugsley (1971) have suggested that a diet containing more phosphorus than calcium is as detrimental as a simple calcium deficiency. The ratio of calcium to phosphorus in bone is 2 to 1. It has been recommended that in early infancy, the ratio should be 1.5 to 1 in older infants, 1.2 to 1 and for adults, 1 to 1. The estimated annual per capita intake in the United States is 1 g Ca and 2.9 g P, thus giving a ratio of 0.35. The danger in raising phosphorus levels is that calcium may become unavailable. 

Calcium carbonate is the salt of choice because it contains the highest amount of elemental calcium and is the least expensive (see Table 88-5). The fraction of calcium absorbed is dose-limited, so maximum single doses of 600 mg or less of elemental calcium are recommended. Calcium carbonate tablets should be taken with meals to enhance absorption. Calcium citrate absorption is acid-independent and need not be administered with meals. Although tricalcium phosphate contains 39% calcium, nonabsorbable calcium-phosphorus complexes may limit overall calcium absorption compared to other products. This product may be required for up to 10% of seniors with hypophosphatemia that cannot be resolved with increased dietary intake. Disintegration and dissolution rates vary significantly between products and lots. Products with good disintegration and dissolution rates and lead contents of less than 1 mcg/day should be recommended. 

The importance of the minerals and the consequences of their deficiency are well known [28], The mineral contents of Chinese, European, and Japanese chestnuts are listed in Table 11.2 [22], European chestnut has the highest potassium content compared to Chinese and Japanese chestnuts. Magnesium, phosphorus, and manganese contents are higher in Chinese chestnut than in European and Japanese chestnuts. On the other hand, Japanese chestnut contains the highest amounts of calcium, iron, sodium, zinc, and copper contents among these three varieties. The minimum and maximum percentages of recommended dietary allowances (RDA) or adequate intake (Al) of these minerals obtained by... 

The intake from the average diet of industrialised countries has been estimated to correspond to a ratio of Ca/P = 1/2, whereas that thought to be really necessary for adults is Ca/P = 1/1. The total phosphorus intake from the average British diet, for example, is well in excess of the recommended level (Table 11.13). 

The recommended daily dietary intake of phosphorus is 300-500 mg for children under 1 year, 800 mg for children under 10 years and 1200 mg for adults. These amounts are easily achieved in a normal diet. It is more important to maintain an appropriate ratio of calcium to phosphorus in the diet than the actual realised amount of phosphorus. Meat, poultry and fish (without bones) contain about 15-20 times more phosphorus than calcium eggs, cereals and legumes contain about 2-4 times more phosphorus than calcium. Only milk, cheese, leafy vegetables and bones contain more calcium than phosphorus. 

---