HEALTH NOTES

Evening Post, Volume CXIII, Issue 54, 5 March 1927, Page 25

HEALTH NOTES

A VAEIED DIET WHAT IT SHOULD CONTAIN (Contributed by the Department of Health.) To maintain the human machine in working order the food or fuel consumed must contain certain substances. To the special steaming properties of New Zealand coal has been attributed the safety of H.M.S. Calliope when she fought her way out of Apia Harbour in the face of a tropical hurricane in which many ships not so supplied were driven ashore. So the human body if it is to weather the varying conditions prevailing on the sea of life must have at its command for maintenance, food or fuel of the right quality, and particularly rich in those life-giving substances known as vitamines, the subject of this article.

Until fairly recently it was considered that a diet containing proteins, carbohydrates, fats, certain salts, and water was sufficient for all purposes. This was quite a reasonable conclusion, because the various articles of diet when- analysed resolved into these various constituents. This diet would probably have remained sufficient if we had beon content to use the natural foodstuffs containing these various constituents. It was only when we began to _ use—chiefly experimentally—artificial mixtures of proteins, carbohydrates, fats, salts, and water in the rearing of animals that it was discovered that this diet, although sufficient chemically, yet had grave deficiencies. When fresh milk was substituted for or added to this artificial diet, these de-I ficiencies disappeared. Yet milk as far as chemical analysis could ascertain, contained nothing other than was contained in. the artificial diet. Yo+ as the animals would grow when milk was added, and not only failed to grow but developed other symptoms when milk was withheld, it was concluded' that milk contained some other substance or substances which eluded chemical analysjs._ To these substances the name "vitamines" or "accessory food fae* tors,?' was given. Since then our knowledge of these substances has increased, and we now know that 1 there are at least four vitamines called respectively A, B, C, and D. SCURVY AND EERI-BEEI. Before proceeding to a discussion of each vitamine two historical facts may be mentioned. It was common among seamen of the eighteenth century and before to have outbreaks of scurvy. The navigators of the latter part of the eighteenth century knew and availed themselves of the curative value of fresh vegetables and frerh fruit juice. In 1804 a ration of lime juice was made compulsory in toe British Navy. During the latter half of the nineteenth century a similar problem- arose in the Japanese navy.. This problem was due to the preval- ■cc of a disease called beri-beri, which, it was discovered, was due to a diet consisting largely of polished rice. When the diet was corrected beri-beri disappeared. It, is now known that these two diseases—scurvy and beri-beri—are due to the absence of two specific vitamines in the diet, and that their cure and prevention lies in providing a diet containing the necessary anti-scorbutic and anti-beri-beri vitamines. VITAMINE A. Vitamine A is known as "fat soluble." Its chief action is one of " growth, promotion," and it is,.essential to young animals. The chief sources of its supply are butter-fat, egg-yolk fat, cod-liver oil, ox fat, green vegetables, etc. This vitamine is absent from practically all vegetable oils. The need for this vitamine is' not so marked in the adult as in the young animal. Its lack in the young causes a cessation of growth, whicli is ultimately fatal. As the body can store, but not manufacture this vitamine, its withdrawal from the diet will not be noticed until the amount stored in the body is depleted. In experimental animals the lack of this vitamine also gives rise to a peculiar affection of the eyes. The want of this substance also leads to diminished resistance to bacterial invasion. As mentioned previously, an animal cannot manufacture this vitamine, so if an animal, such as a cow, it not fed on a diet containing this vitamine A, then its milk and the butter manufactured from the cream will be deficient. The animal world is dependent on the vegetable world for its supply of vitamines. Thus the cow derives its vitamines from the green feed it takes, and having secured its supply, the animal passes it on to humans per medium of its milk and milk fat. One of the richest sources of vitamin A is cod-liver oil. The codfish secures it from its ultimate vegetable sources, stores it in the liver, and passes it on to us per medium of the oil expressed from the liver of the cod. The codfish is carnivorous and feeds on smaller fish, such as herrings, squids, shellfish, and these again on still smaller fish, until ultimately we get down to small vegetable organisms (diatoms) that live in the sea, and these diatoms, are the ultimate source of the vitamine ' A that is provided for us in cod-liver oil. These diatoms are capable of manufacturing this vitamine from its constituent elements. Vitamine A. is fairly resistant to heat. VITAMINE B. Vitamine B is water soluble. It is called the anti-neuritic vitamine. One of its functions is also- that of growth promotion. Deprivation of this vitamine affects both adult and young animals in the same way. There is usually a fairly rapid loss of weight, which -nay terminate fatally. The chief disease that is caused by a lack of this vitamine is beri-beri. which occurs in two forms, called, respectively, wet and dry beri-beri. This vitamine is very resistant to drying and moderately-resistant to heat. The chief sources of it are cereals and pulses, eggs, yeast, and vegetables. It occurs in a slight amount in meat (liver and kidney) and in milk. It is absent from fish, fat of all kinds, and meat extracts. In seeds it is present mainly in the embryo, and as in moderr. methods of milling this embryo is rejected, vitamine B is absent from white flour, polished rice, etc. Its absence from diet causes almost immediate cessation of growth, rapid loss of weight, and gastro-intes-tiual disturbances. Peripheral neuritis may also decelop. VITAMINE C. This is also water-soluble. Its chief source is plant tissues, which are actively growing. It occurs in fresh vegetables (especially cabbage, swede turnips, onions, and in less amount in potatoes), fruit juice (especially of oranges, lemons), raw meat juice, milk, and some ■ dried fruits. It is absent from pulses and cereals, but will appear in them when they are allowed to germinate. It is absent from dried vegetables, dry cereals, and pulses, tinned and super-heated foods and yeast. This vitamine is very sensitive to drying and is rapidly_ destroyed thereby. It is also very sensitive to heat, and the amount present rapidly diminishes during cooking. It is rapidly destroyed by alkalis and hence the adding of sodium salts to the water in which -vegetables are cooked'rapidly destroys the vitamine. Its absence from, or insufficiency in, our food leads to the development of scurvy. VITAMINE D. The separation of this vitamine is a comparatively recent occurrence. It ocj curs in cod-liver oil and other natural

animal fats and green vegetables, ana has only recently been separated fronts vitamine A. It is fat soluble, and is less easily destroyed khan A. Its absence is the cause of rickets. The peculiar thing about this vitamino is that its presence seems to be related to exposure to unfiltered sunlight. Only, certain light rays have the power to' activate this vitamine, and these -onstitute what is called the ultraviolet rays. The sun's rays lose this power when they are allowed to pass through ordinary glass. Another interesting point is th.\t this vitamine D can be developed in certain, substances that do not normally contain it by exposing them to the sun's rays or ultrarviolejj Hglit. The chief of these substances is called cholesterol, which is a constituent of many natural foodstuffs. These foodstuffs, which includo dried milk, flour, meals, cotton seed oil, lettuce, spinach, etc., all develop anti-rachitic properties when subjected to ultra-violet radiation. WHAT DIET SHOULD CONTAIN. Thus we see from this brief account how important these vitamines are and also we see how each and every one of us can secure a sufficient supply "of them: Also, it will be evident that in these days of ultra-refined foods, without much trouble, we can easily fail to secure the necessary amount of these vitamines. A diet which contains milk, eggs, butter, wholemeal, green vegetables, fresh meat, and fruit is not likej ly to be deficient in any one vitamino.