Calcium is one of the most important mineral required by body to maintain it healthy.

• Generally, body of an adult normally contains about 1200 g of calcium. At least 99% of this is present in the skeleton, where calcium salts (chiefly hydroxyapatite), held in a cellular matrix provide the hard structure of the bones and teeth. Obviously all of this calcium comes from the diet.

• Among common foods, the calcium-containing protein of milk (caseinogen) is much the richest source, which is one reason why milk and cheese are especially valuable for growing children. Half a liter of cow’s milk contains about 06 g of calcium.

• Most other foods contribute much smaller amounts. However, peas, beans, other vegetables and particularly cereal grains are frequently the chief contributors because of the large amounts eaten.
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• Drinking water can provide significant amounts of calcium. In Britain the average intake from this source is about 75 mg Ca/day; but the variations are large: from none in water from peaty, acidic hill lochs in Scotland to 200 mg or even more in water obtained from wells sunk in chalk or limestone.

• About 70 to 80% of the calcium in the food is normally excreted in the faces. Calcium absorption may be impaired either by lack of vitamin D, by any conditions causing small intestinal hurry, by the combination of calcium with excess fatty acids to form insoluble soaps in steatorrhoea, or by certain substances in the diet which can form insoluble salts with calcium. These include foods rich in oxalic acid (e.g. spinach) and phytic acid which is present in the outer layers of cereal grains. Hence ‘whole meal’ bread contains more phytic acid than white. To overcome the influence of phytic acid, calcium carbonate has been added to flour in Britain.

• World Health Oganization recommends a daily intake of 500 mg for adult men and women, rising to 1200 mg during pregnancy and lactation. For adolescent boys and girls the recommended intake is 600 to 700 mg daily.

• In many parts of Africa and Asia children develop healthy bones and adults remain in calcium balance despite calcium intakes which may be no more than half the above recommendations. Abundant sunshine possibly produces this effect. However a daily intake of 1000 mg should be taken during pregnancy and lactation.

• Deficiency of calcium and vitamin D go hand in hand and are best considered together.