Minerals are essential for building the body and for the maintenance of health. For this reason they may be regarded as nutrients. The chief mineral substance in food are sodium, potassium, calcium, phosphorus, iron, and iodine.

Sodium and chloride or common salt is a compound of sodium and chloride. It is required by the fluids in the body.
 The body loses salt in the urine and in the sweet.
The kidneys are able to control the amount of salt passed out in the urine, but there is no means of control over that lost in sweet; therefore extra salt should be taken in food in hot climates and by people whose work is done at high temperature,
and after strenuous exercise, so as to keep the required supply needed by the body fluids. Vegetarians usually required more salt than animals food eaters because of the large amount of other minerals substances found in vegetables which have to be counterbalanced by sodium chloride.

Potassium is found in vegetables and fruits. it is required for the red cells of the blood.

also calcium is necessary for:
1: Proper development and growth of bones and teeth,
2: normal clothing of blood,
3: normal functioning of muscles.
The chief source of calcium are cow's milk, green vegetables, eggs, fish, and cheese. A growing child needs about twice as much calcium as an adult.

Phosphorus is required, with calcium, for the building of bones and teeth. it is also required for the proper working of the nerves and for the structure of all the cells in the body.
It is found mainly in milk, eggs, fish, liver, kidney, and cheese.

Iron: this is found in chiefly in liver, meat, pulse, green vegetables, and wholemeal flour. It is a necessary constituent of the blood cells and essential for the transportation of oxygen round the body.
Iron that has been absorbed by the body is lost only very slowly, since the cells are able to use it over and over again. In spite of that, food containing iron must be eaten in order to maintain the supply, because an insufficient supply may result in anemia.
Sometimes it is necessary for people who suffer from anemia to take iron in medicinal or tonic form.

Iodine is necessary to the thyroid gland in the neck which is concerned with the development and metabolic rate of the body.Goitres are often a sign of in-sufficient iodine in the diet.
Iodine is drive from;

1: drinking water and water used in cooking foods.
2: sea fish, oysters, etc.
3: certain vegetables, e.g onions, watercress grown on soil naturally containing traces of iodine. At or near the sea there is plenty of iodine which is carried by the windand sprayed inland.