“Now in my laboratory I kept a stock of several hundred rats for breeding purposes. They lived under perfect conditions: cleanliness, roomy cages, good bedding, abundant fresh water, fresh air, and sunlight–all these things they had; and they were fed on a diet similar to that of a race whose physique was very good. They were kept in stock from birth up to the age of 2 years–a period equivalent to the first fifty years in the life of human beings. During this period no case of illness occurred among them, no death from natural causes. no maternal mortality, no infantile mortality except for an occasional accidental death. In this sheltered stock good health was secured and disease prevented by the combination of six things: fresh air, pure water, cleanliness, sunlight, comfort, and good food. Human beings cannot, of course, be so sheltered as these rats were, but the experiment shows how important these things are in maintaining health.
DIET AND DISEASE
“The next step was to find out how much of this remarkably good health and freedom from disease was due to the good food: food consisting of whole-wheat flour cakes, butter, milk, fresh green vegetables, sprouted pulses, carrots, and occasionally meat with bone to keep the teeth in order. So I cut out the milk and milk products from their diet, or reduced them to a minimum, as well as reducing the consumption of fresh vegetable foods, while leaving all other conditions the same. What was the result? Lung diseases, stomach diseases, bowel diseases, kidney and bladder diseases, made their appearance. It was apparent, therefore, that the good health depended on the good diet more than on anything else, and that the diet was only health-promoting so long as it was consumed in its entirety; so long, in fact, as it contained enough milk, butter, and fresh vegetables.
“Many more experiments were done which showed that, when rats or other animals were fed on improperly constituted diets, such as are habitually used by some human beings, they developed many of the diseases from which these human beings tend to suffer: diseases of the bony framework of the body, of the skin covering it, and of the membranes lining its cavities and passages; diseases of the glands whose products control its growth, regulate its processes, and enable it to reproduce itself–diseases of those highly specialized mechanisms–the gastro-intestinal tract and lungs–designed for its nourishment; diseases of the nerves. All these were produced in animals under experimental conditions by feeding them on faulty human diets. Here is an example of such an experiment. Two groups of young rats of the same-age were confined in two large cages of the same size. Everything was the same for each group except food. One group was fed on a good diet, similar to that of a Northern Indian race whose physique and health were good, and of which the composition is given above. The other was fed on a diet in common use by many people in this country, a diet consisting of white bread and margarine, tinned meat, vegetables boiled with soda, cheap tinned jam, tea, sugar, and a little milk: a diet which does not contain enough milk, milk products, green leaf vegetables, and whole-meal bread for proper nutrition. This; is what happened. The rats fed on the good diet grew well; there was little disease among them, and they lived happily together. Those fed on the bad diet did not grow well; many became ill and they lived unhappily together, so much so that by the sixtieth day of the experiment the stronger ones among them began to kill and eat the weaker, so that I had to separate them. The diseases from which they suffered were of three chief kinds: diseases of the lungs, diseases of the stomach and intestines, and diseases of the nerves–diseases from which one in every three sick persons among the insured classes, in England and Wales, suffers.”