Calcium is absorbed from the intestines and aids in the utilisation of Vitamin D to make strong bones and teeth. It is also required for the proper clotting of the blood; for the benefit of the heart, the muscles and the nerves; and to reduce fatigue and increase stamina and mental alertness. Lack of it is a cause of rickets, osteomalacia, contraction of the muscles, brittle nails, fits and other mental disorders, skin complaints and dry hair. Women have a tendency to lose large quantities of calcium when they bear children in fairly quick succession and they also lose quite a lot when they breastfeed their babies. For the benefit not only of themselves but also of their babies, it is essential that this loss is made good. Growing children too need extra quantities of calcium, as their bones grow and they develop new teeth.
In a normal diet, only about 25 per cent of the calcium is utilised by the body, and even this percentage is dependent on the amount of Vitamin D that has been absorbed. The remainder is lost in the motions of the bowels. To obtain as much calcium as possible, the following foods (listed in descending order of the amount of calcium they contain) should be included in the diet: powdered dried skimmed milk, Cheddar cheese, tinned sardines, watercress, cabbage, grains, eggs and white fish.