a reserve of energy and in an emergency would lack resisting power.
This, of course, is a rough general estimate, and could not be laid down as a hard and fast rule, for all to follow. If the food of each individual were properly balanced and each of the glands and tissues found just the right kind and the right amount of nutriment in the blood stream to maintain the integrity and perfect balance of the entire body, there is no doubt that the level of human efficiency would be raised very much higher than it is to-day. But no physician, no physiologist living, could possibly make out a bill of fare that would meet the needs of all alike.
No common diet could be prescribed for everybody. Each individual, according to his age, his physical condition, and his temperament would have to make exceptions and study his own requirements. But we know by experience that people living under different conditions, doing different kinds of work, are very materially helped by foods especially rich in the elements which enter into the structure and maintenance of the tissues which are most active in that sort of life or vocation. The kind and amount of food required by different people depend a great deal upon the degree of rapidity with which the cell life of any particular tissue or organ is broken down by its activity. The brain and nerve cells, for example, are broken down very rapidly in intense mental exercise or mental application, whereas destruction would be comparatively light if the brain were used very little, as in the case of persons whose activity is chiefly muscular.
It is well known that animals should be fed according to the work they do and their mode of living. A hunting dog requires a different food from a house dog. A driving and trotting horse, a race horse, requires a very different food from a dray horse, that carries a heavy load. Speed requires food like oats, which gives up a quick energy. Corn is too heavy for the speed horse. On the other hand, oats do not have the same staying power as corn.
The human animal must also be fed to fit him for his particular work. What would you think of a trainer who would constantly stuff a young athlete with all sorts of food he could get regardless of its properties, whether it made fat or muscle? You would certainly think the man did not know his business. Even those who have not studied the matter know that an athlete must be trained for speed, endurance, or muscular strength, according to the nature of the contest. Every bit of food that does not help toward this end is excluded from the diet. All foods that tend to produce fat instead of sustaining prolonged muscular effort are cut off. Every bit of material that will burden,—all overeating, is forbidden. Every mouthful which is unnecessary for sustenance and strength building, which would be an additional tax upon the digestive organs and the nervous tissues, in order to get rid of its injurious effects, must be excluded. The problem is to produce the maximum of muscular strength and endurance, to take only the foods which can sustain the heart in its stupendous strain, in running, leaping, wrestling, etc. The great object is to build up perfect muscle fiber and to eliminate everything which would tend to produce fat cells in the muscles, especially in the heart muscles, which would tend to weaken the vigor of its stroke.
The first consideration in the food question is to supply the physiological requirements of the body without a lack or scantiness anywhere which would cause deterioration in any tissue, or a surplus which would clog the organs and result in poisoning the body through the decomposition of half-digested foods.
For example, a person engaged in an athletic contest, like bicycle racing, carried on for a week or more, would need a great deal of energy-producing material to supply the rapid waste of broken-down tissues in the muscular system. This need must be quickly supplied by foods which are combustible in the body and which yield a large amount of energy and comparatively little of what we might call the tissue-building elements, because the principal loss of persons in such a contest is in the energy and heat producing products which come from rapid combustion. If a contestant took too much animal food he would get an oversupply of the tissue-building material,—too much albuminous and nitrogenous food, and too little energy-producing material.
On the other hand, many experiments on animals have shown the evil effects of an excess of the latter kind of food, which causes a very rapid deterioration in the physical life, especially in the lining cells of the alimentary tract and seriously interferes with the digestive and absorptive processes, so that the foods are not completely absorbed, assimilated and transformed into life tissues. For instance, a dog, if fed largely upon rice, will not have sufficient structure-building material, and a fatty degeneration will take place in the mucous-membrane lining of the alimentary tract, so that if this diet is continued very long the absorptive power in the alimentary tract will become so impaired that the animal ultimately will not thrive even if its natural diet is restored.
There are many food elements which are necessary to the integrity of the bodily tissues. For example, there is no animal life in which phosphorus does not play an indispensable part; and, if we should eat food which does not contain any of the phosphorous compounds, life would rapidly decline. The brain would quickly deteriorate if deprived of phosphorus, which is found abundantly in the yolks of eggs, in fish, in milk, cheese, etc. Cereals and legumes also contain much phosphorus.
Most people, especially the poor, eat more than twice as much starchy food as is required by the system; and, as they do not get enough of other foods, some of their tissues are starved. Those who live largely upon the products of fine flour overtax that part of the digestive system which takes care of the starchy food, and they often suffer from an overacidity of the stomach and sometimes of the saliva, which latter is very injurious to the teeth.
Children, of the poor are often born with rickets, because the mothers have lived mainly on white bread and tea and have not themselves had sufficient bone-making material to transmit to their children for the building of their skeletons. Some of these children have not enough backbone to hold up their heads, and they become deformed in all sorts of ways,—if they ever reach maturity,—because after they are born they do not get enough of the material they lacked before birth to build up and remedy their defects. A child needs much phosphorus, lime, magnesia, and silica for his skeleton, which is the principal part of his little body, and he should be nourished with the object of growth in view. Yet many children are fed chiefly on fine white flour products and tea, and often coffee. It ought to be regarded as a crime to feed children on such things!
No infant can digest solid foods until it cuts its teeth. Children should have plenty of milk until they are eight or nine years old, otherwise the bones will not get sufficient lime and other earthy salts to harden them, and rickets or bone diseases of some sort are likely to develop. While the body is in process of construction, all the tissues require a great deal more building material than when it has reached maturity, and milk contains everything necessary for early body-building. It is the only perfect food, and contains forty different substances. For proper development it is imperative to have every tissue in the body nourished, and to have every element in food which can build the tissues, furnish the fuel for combustion, and supply heat and the various energies for all the bodily activities. Some food authorities go so far as to say that drinking milk is almost like drinking blood, because, if pure and rich, it is such a great blood maker.
While milk is the only food which contains every element that enters into the human body, such as oxygen, hydrogen, nitrogen, carbon, phosphorus, sulphur, etc., yet taken alone it is not so well suited for an adult as for a growing child, because it contains too much building material, although that is the most important factor before the body reaches maturity. Later in life there is not much body building, but we require food for maintaining and sustaining the body already built. At the same time, a certain amount of milk, or its equivalent, is needed all through life; and, in some cases of weak digestion and certain other ailments, a diet composed almost wholly of milk has had very beneficial effects.
Our diet should be chosen according to our individual needs, as determined by our age and our vocation. It should be planned to enable us to express the maximum of our ability, our efficiency, in whatever line of endeavor we are engaged, whether it involve mental or muscular effort. Yet in some families there are half a dozen members who represent
