Food sources of calcium and phosphorus
Milk and milk products are the most important sources of calcium in readily available form. A few of the green, leafy vegetables are good sources of calcium, but others, such as spinach, chard, beet greens, and rhubarb, contain oxalic acid which forms insoluble calcium oxalate and thus may render the calcium unavailable. In most sections of the country greens are not used regularly enough or in sufficient quantity to be relied upon to replace milk, but they are important when milk is scarce or unobtainable. Meats and poultry are poor sources of calcium. Cereal products contribute little, except where breads are enriched with calcium or are made with a high percentage of milk solids. The pattern dietary of 1400 calories provides almost the recommended allowance of800 mg (0.8 g), which is supplemented by the calcium of the fooels added to make up the needed calories.
Phosphorus is more widely distributed than calcium and is more likely to be high than deficient in the average diet. poultry, fish, meats, cereals, nuts, and legumes, as well as milk and milk products, are all good sources. Phosphate additives used in a wide variety offood products, such as carbonated beverages, processed meats and cheeses, dressings, and refrigerated bakery products, may contribute significantly to the total phosphorus intake of many. In the cooking of vegetables, there may be slight losses of calcium and phosphorus, especially if the cooking water is discarded.
