NUTRITION.

Otago Daily Times, Issue 18857, 9 May 1923, Page 6

NUTRITION.

THE NEWER KNOWLEDGE OF DIET.

OTAGO INSTITUTE PRESIDENTIAL ADDRESS.

The first meeting for the year of the Otago Institute took place in one of the Museum classrooms last evening. The president, Dr J. Malcolm, presided, and there was an attendance of some 70 or £O. At the outset Dr Malcolm returned thanks for his election, and referred to the attractive programme that has been drawn up for the coming winter activities of the institute. Dr Malcolm proceeded to deliver the annual presidential address on ‘‘The Newer Knowledge of Nutrition,” mentioning that this is the title of a valuable work by Professor M'Collum, of the John Hopkins University Certain effects of food on health must have been' observed and noted very early in the history of the human race, and these observations were gradually formed into maxims and aphorisms and eventually recorded in writing. One of the earliest medical writings known was on the subject of regimen. In all the older medicine great attention was paid to dieting. In the seventeenth century there was a remarkable old gentleman called Sonet onus, who worked on obtaining a measurable method of recording the effects of food on bodily weight. The great name that came next was Lavoisier, to whom we owed largely the development of modern chemistry. It was he who first showed the meaning of oxidation and that it took place in - the, human body. He unfortunately became involved in the maelstrom of the French Revolution and ended his life on the guillotine at the age of 51. In the nineteenth century a great advance occurred in the science of nutrition, and it became clear that there were certain chemical substances always present in food, the proteins, the carbohydrates, and the fats. Those three constituents were present in the diet of every race in every land. Up to the end of last century great stress was laid on the proportions of these constituents and rightly so. The amounts were found to be wonderfully close in the diets common in different lands —protein about 100 grammes, carbohydrates 400 fo 500 grammes, and fat from 50 to 100 grammes. Man seemed instinctively to take about 100 grammes of protein daily in the various articles of his diet. . For a time it was believed that the sum and substance of dieting was to have these substances properly balanced and, of course, in digestible form. _ Fat was perhaps the most easily recognised of the three food constituents, and it was more difficult to distinguish between carbohydrates and proteins! Carbohydrates Were sweet to the taste, and swelled on cooking. Protein itself- was tasteless, and it became less soluble on cooking. The bulk of the living body, its protoplasm cells, was largely protein, end we took in protein to restore the worn-out cells. We could not make protein in the body. Two great principles evolved were that you must have sufficient protein in the diet, and that food must he capable of sustaining the body warmth. All three! food groups combined to make heat. It was early found 1 that gelatine, though! a protein, would not take the place of other proteins in sustaining life. It yielded fuel for, the body, but would not repair tho tissue. He described the constitution of the molecule of protein, with ifi 16 or 18 constituent amino acids, each with their own peculiar structure. Some of these constituents were, essential to life. There were certain proteins in the body that - were always breaking down and had to be replaced. A number of different proteins bad to be used to supply the peculiar constituents of tho body protein, and consequently attention must be given to tho quality of the protein used as well as to ita quantity. The rat had proved a suitable animal for experimental purposes on account of tho brief span of its life and of its smallness, which allowed experiments to be made on numbers at a time. Ho indicated what a great field there is for experimentation ’tc find combinations of vegetable foods which, while economical in price, are also satisfactory in their nourishing properties. Ho showed why the combination of leaf food and seed, or root foodj is a valuable one from a dietary point of view. The lesson was to advocate greater use of green vegetables. He was an advocate of the use of milk, but pointed out that it was not a typical food for on adult. It had many disadvantages. It was not a ■good stimulant of the gastric juice, and it lacked iron. Green vegetables supplied all the good' qualities of milk and others besides. He proceeded to discuss the vitamines, of which there were at present believed to be three, known as A. B, and C. He described the investigations lending up to the discovery of the vitamines, and referred to the connection between beriberi and a rice diet. Beri-beri was eventually shown to be wholly due to deficiency in diet. The body could,not grow unless it haJ, in addition to proteins, fats and carbohydrates vitamines A and B. Ha showed a considerable number of lantern slides _of hens, pigeons, and rats, and of graphic curves, id] illustrating the fact that growth and development cease without certain quantities, of both vitamine A and vitamine B. Scurvy was now known to bo due to the absence of minute quantities of vitamine C, which is' found in citrous fruits and in green vegetables. Speaking of the future, Dr Malcolm said 1 there was every likelihood that w-e, would bo able greatly to increase longevity by improved knowledge of nutrition. There was great need , for study in nutrition in this dominion for our primary products, and the general health of the people could be greatly improved by health research institutes such as existed* in America.. The address throughout was freely illustrated with lantern slides showing the results of numerous experiments in nutrition mostly made upon rats. On the motion of Mr H. Brasch, Dr Malcolm was accorded a very hearty vote of thanks.