OUR MINERALS

New Zealand Listener, Volume 10, Issue 258, 2 June 1944, Page 30

OUR MINERALS

(Written for "The Listener’ by DR.

MURIEL

BELL

Nutritionist to the

Department of Health)

NYONE who imagines that this is to be a discourse on either geology or fertilisers will be disappointed. For we are talking about food. It is well known that minerals of various kinds are needed by the body. Over 4 per cent of the body.consists of mineral matter; and without the inclusion of mineral elements in their food, animals do not survive. Four-fifths of the minerals reside in the skeleton; these boneminerals are chiefly calcium and phosphorus, with lesser . amounts of a number of other elements. Apart from the needs of the skeleton, there are the important needs of the rest of the body for calcium and phosphorus, and for sodium potassium, magnesium, sulphur, iron, and various "trace" elements which occur in minute amounts. When these minerals and other elements are put into pure water in the correct proportions, warmed to body heat and saturated with oxygen, the fluid can be used to keep a heart beating. The concentration of these various salts of sodium, potassium, calcium, etc., is somewhat similar to the proportions in which they are found in sea-water. The latter is, of course, a stronger solution; it is thought that originally life began in water; the body enclosed some of its watery environment, and elaborated it until finally the blood evolved, still with the original elements that were present in sea-water. The latter has meantime grown more concentrated, and now represents a dangerous fluid for us to take into our bodies if we are suffering from thirst at sea. The balance of these minerals is very~ nicely preserved in the body; too much calcium would make the heart go faster until it stopped in a permanent state of contraction; too much potassium would cause it to go on strike in a dilated state. The body simply does not allow this state of affairs to eventuate, for it gets rid of any excess, provided that the tissues are in a healthy state; and thus preserves the proper equilibrium between calcium, potassium, etc. Physiologists use for this the expression "maintaining the constancy of the internal environment," a very necessary state of affairs for the proper function-~-ing of our bodies. Upset the balance, for example, by diminishing the amount of calcium in the blood, and the body’s nerves get on edge; when this happens, as it does sometimes in rickets due to low calcium intake, convulsions may be the outcome. This does not often occur in New Zealand, but it was not infrequently seen in the children’s wards in Vienna even in 1928, aes