Common Salt

New Zealand Listener, Volume 11, Issue 265, 21 July 1944, Page 16

Common Salt

(Written for "The Listener" bv DR

MURIEL

BELL

Nutritionist 3 to the

Health Department).

HE part played by common salt (or sodium chloride) in the body is a very important one. We find it in the fluid part of the bloodwhile potassium salts are present in the blood cells-a curious state of affairs, kept so by the control of the adrenal gland. We similarly find it in the thin layer of fluid that bathes the cells of the body. We find also that it is the raw material from which the acid of our gastric juice is made. It plays a very important part in the regulation of osmotic pressure between cells and the fluids that bathe them. The body contains more potassium than sodium, and Nature makes provision for this during growth by having @ ‘greater proportion of potassium to sodium in milk (2.5 to 1). However, as soon as foods from the vegetable kingdom which contain a large proportion of potassium begin to be included in the infant’s diet, the potassium is liberally provided by these latter foods. As long as a child is healthy, it can therefore take common salt in its food. In experimental work on animals, it is found that even large amounts of sodium chloride does not interfere with normal growth. This illustrates the capacity. of the normal body to remove any excess by excreting it, More Than Necessary It is generally thought by physiolog--ists that we take more salt than is actually necessary. Natives living inland in New Guinea live on as little as 2 grams of sodium chloride dailyobtained by getting the ash from burning a certain grass. In New Zealand most of us take from 6-10 grams, half of which comes through our bread and butter. The proportion of sodium to potassium in grass is 1-18, Herbivorous animals undergo a hunger for sodium chloride — the farmer puts out rocksalt licks for them. This craving that they suffer arises through their needs for making their digestive juices-a herbivorous animal has a much longer alimentary system than we have, and its digestive system has to do so much work’ that the net gain from its food is only 50 per cent of the calories that it ingests, the other 50 per cent being expended in the movements of its long intestinal canal. The digestive juices that it pours. out require sodium chloride-hence the. need for salt. Salt permits in man a freer flow of saliva and gastric juice, and an increased sense of well-being. The use of common salt in cooking provides for physiological needs. However, it is thought that its use should not be overdone. A total of a teaspoonful (one-sixth of an ounce) is about the amount that ordinary adults should take in and on their home-cooked food per day, and in New Zealand this should all be iodised salt. When sweating is excessive and continuously so, as in the case of stokers on ships, a large amount of salt may be lost in the sweat, leading to "heat cramps," due to insufficient sodium chloride bathing the muscle fibres. This is overcome by adding a little salt to. their drinking water.