IN recent years, numerous experiments have been conducted in an effort to ascertain the exact nature of the faults in diet which lead to such diseases as beriberi, scurvy, pellagra, etc., declared by some investigators to be due to a lack of specific chemical substances in the diet.
The relation between disease and faulty diet was first brought to the attention of scientists about the year 1880, by the experience of the Japanese navy. The prominent place of rice in the diet of those who suffered of beriberi, led to a belief that it was a causative factor in the disease. In 1897, Eijkman took up the study of nutrition, demonstrating by experiment the fact that when pigeons were fed exclusively upon polished rice, they began to suffer of a nervous disorder, staggered, lost their power to stand up, or even to swallow food, and finally died. In other words, the pigeons developed a state of polyneuritis (inflammation of many nerves Dorland), which is analogous to beriberi in man. He found, more over, that when the pigeons were fed on the entire kernel, the disease did not develop.
In 1911, Dr. Casimir Funk took up the study of beriberi, and made an effort to isolate this singular yet unidentified substance contained in rice polishings, and also to determine what other foods contain it, and what influence it has on the health. He called this mysterious but absolutely indispensable substance “vitamine.” The results observed among his birds when they were restricted to milled rice and water were identical with those reported by Eijkman. He found that when the coatings that had been removed from the rice were soaked in water, and a little of this fluid was passed through a tube into each sick bird’s crop, or, if the birds had not reached the stage where they could not swallow, a portion of the rice polishings was fed to them, in a few hours they made rapid recovery, and before the day was over they were apparently as well as ever.’ It seemed like a veritable miracle. Evidently the Creator has placed in the covering of the rice something that is absolutely essential to life, and that the rest of the grain can-not supply.
Funk demonstrated, furthermore, that when fowls were fed on steel roller process white flour, in three or four weeks they were afflicted just as when they were fed on polished rice. That is, he discovered that the vitamines are in the outer layers in wheat, just as they are in rice. These experiments clearly proved that there is required in the diet something more than protein, carbohydrate, fat, and mineral salts.
In 1914, W. Richard Ohler, M. D.,’ carried out a number of experiments with chickens, in order to furnish experimental proof for the contention that a more or less exclusive diet of white bread was the chief cause of beriberi in Newfoundland. Fourteen chickens fed on white flour bread, with or without yeast, died within twenty-eight to forty days. Before death, the birds exhibited symptoms of polyneuritis, and histological examination of the peripheral nerves revealed considerable degeneration. Five chickens fed on whole wheat bread, and two on whole wheat, lived in perfect health for seventy-five days, when the experiment was discontinued.
Beriberi is a serious disease of the nervous tissues. As it progresses, it affects every tissue in the body and eventually the heart, and is fatal unless a substance containing anti-neuritic vitamine or more definitely, water-soluble B is administered. The pigeons in the former case, like the chickens in the latter, had beriberi. Observe that the rice with which the pigeons were fed was good rice, the ordinary white kernels commonly bought at the grocery, the hulls having been removed to make it attractive and to improve the keeping quality. The white bread that resulted in disease and death to the chickens in the latter case, was good bread, such as is commonly bought at bakeries. But the food was lacking in the essential accessory substances, the vitamines.
Hopkins’ discovered that small additions of milk to food mixtures of purified protein, carbohydrate, fat, and inorganic salts, rendered them capable of inducing growth, whereas without such additions of milk, no growth could be secured. He interpreted this to mean that milk contains unidentified chemical substances indispensable to the diet, and that the failure of animals to grow, and to have a normal length of life, was caused by the absence of these essentials, which he designated “accessory” substances.
Experiments by McCollum and Davis’ brought out the fact that although chemical analysis of whole grain cereal shows it to contain all the essential food substances, such as protein, starch, sugar, fat, and all the mineral salts that occur in the body of an animal, cows did not do well when fed strictly on seeds or seed mixtures. But when they were fed on a corn mixture, including the seed, straw, and leaf of the plant, their nutrition was excellent, as shown by their appearance, the vigor of their offspring, and their ability to produce an abundance of milk. This indicated a dietetic value in the leaf of the plant.
The work of these men showed, moreover, that certain fats, as butter fat, egg yolk fat, and numerous products of the plant kingdom, contain something that greatly stimulates growth when added to a diet of purified foodstuffs. Funk and Macallum pointed out that butter does not relieve polyneuritis in pigeons. McCollum and Kennedy, after giving several reasons why the term “vitamines” was unsatisfactory, proposed the provisional terms “fat-soluble A” and “water-soluble B,” because of the characteristic solubility of these substances in fats and water respectively.
(Since this was given out by McCollum, a third dietary essential has been discovered.)