These foods are eaten because they are rich in protein. Protein is the great builder and repairer of the body. It forms the framework for both bone and muscle. We can get along very well without starch or sugar or fat, but it is absolutely necessary to have proteid foods. They are the only ones that contain nitrogen, which is essential to animal life.
Nitrogenous foods are used not only to build and repair, but in the end they are burned, supplying as much heat as the same weight of sugar or starch.
Proteid foods are generally taken to excess. To most people they are very palatable, and they are generally prepared in a manner that renders rapid eating easy. Besides, meats contain flavoring and stimulating principles, called extractives, which increase the desire for them. The consequence is that those who eat meat often have a tendency to eat too much. Excessive meat eating often leads to consumption of large quantities of liquor. Stimulants crave company.
As will be noted, most fish and meat contain about 20 per cent. of protein, while about 75 per cent. is water. The fatter the meat, the less water it contains, and the more fuel value it has. The leaner the meat, the more watery the animal, and the more easily is the flesh digested. Beef is fatter than veal and harder to digest. Also, the flesh of old animals is more highly flavored than that of the young ones, because it contains more salts. For this reason people who have a tendency to the formation of foreign deposits, as is the case with those who have rheumatism and gout or hardening of the arteries, should take the flesh of young animals when it is obtainable.
In the past we have been taught to partake of excessive amounts of protein. The prescribed amount for the average adult has been about five ounces. If we were to obtain all the protein from meat, this would necessitate eating about twenty-five ounces of meat daily. However, inasmuch as there is considerable protein in the cereals and milk, and a little in most fruits and vegetables, a pound of meat would probably suffice under the old plan. A few physicians have known that such an intake of protein is excessive, and now the physiologists are learning the same. It has lately been determined experimentally that the body needs only about an ounce of protein daily, which will be supplied by about five ounces of flesh. Three or four ounces of flesh daily make a liberal allowance, for it is supplemented by protein in other foods.
Workers eat large quantities of flesh because they think they need a great deal. The fact is that very little more protein is needed by those who do hard physical labor than by brain workers. The extra energy needed calls for more carbohydrates, not for protein.
When the organism is supplied with sugar, starch and fat, or one of these, the protein of the body is saved, only a very small amount being used to replace the waste through wear and tear. Though protein can be burned in the body, it is not an economical fuel, either from a physiological or financial standpoint. The energy obtained from flesh costs much more than the same amount of energy obtained from carbonaceous foods. Ten acres of ground well cultivated can raise enough cereals and vegetables to support a number of people, but if this amount of land is used for raising animals, it will support but a few. The protein obtained from peas, beans and lentils is cheap, but these foods do not appeal to the popular palate as much as flesh.
Meat immediately after being killed is soft. After a while it goes into a state of rigidity known as rigor mortis. Then it begins to soften again. This third stage is really a form of decay, called ripening. It is believed that the lactic acid formed is one of the principal agents producing this softening. Some people enjoy their meats, especially that of fowls and game, ripe enough to deserve the name of rotten. The ripening produces many chemical changes in the meat, which give the flesh more flavor. Consequently those who indulge are very apt to overeat. It is a fact that those who eat much flesh go into degeneration more quickly than those who are moderate flesh eaters and depend largely on the vegetable kingdom for food.
If an excess of good meat causes degeneration, there is no reason to doubt that partaking of overripe foods is even worse.
All meat contains waste. If the flesh comes from healthy animals and is eaten in moderation this waste is so small that it will cause no inconvenience, for a healthy body is able to take care of it. If too much is eaten, the results are serious. Overeating of flesh is followed by excessive production of urea and uric acid products. Some of these may be deposited in various parts of the body, while the urea is mostly excreted by the kidneys. The kidneys do not thrive under overwork any more than other organs. The vast majority of cases of diabetes and Bright's disease are caused by overworking the digestive organs. Too much food is absorbed into the blood and the excretory organs have to work overtime to get rid of the excess.