PART VII

FOODS AND DIETS

The discussion of this subject is from the broad standpoint of the need of the body for the various elements of nutrition. It is also purposed to outline the values and uses of the various foods, but it is not intended to discuss the physiology of nutrition more than to state the fundamental basic principles for the practical advice given. A few facts are presented that every practitioner must know in order to properly treat his patients, as the age of "drugging" is past. It must now be the object of every physician to modify, if possible, disturbances of the system by changes in the food and drink before drugs are called upon for aid. As elsewhere stated, the better the clinician understands physiology, the better therapist he is.

Growth and body up-keep depend largely upon proteins; energy (work, heat, and physiologic activities) depends upon carbohydrates, sugar and fats. Salts are necessary for tissue building and for other chemical interaction of the body. Water is needed for tissue building, for circulation, for digestion, for most physiologic processes, for elimination of waste products, and for the necessary loss of heat.

Any exercise no matter how slight, even the difference between sitting and lying, increases the need for energy-giving foods. Growing boys and girls require about 25 per cent. more food, relatively, to their weight, than do adults, especially the energy foods. Men require more food than women; large men (not fat men) require more than small men, though a small man may require relatively more food than a large man. The more the exercise, the more the energy food required. An individual with fever requires more energy foods than when he is well and at rest, though ordinarily not as much as when he is well and at work.

The unit of measure of the fuel value or energy content of foods is the calorie, which is the amount of heat required to

raise the temperature of a kilogram of water 1 degree Centigrade. The energy value of all foods is measured by this unit. A man weighing 150 pounds requires food yielding about 2500 calories per day, if his work is largely sitting and he does no active labor. The more standing or other simple exercise, as well as the more the physical labor, the more calories needed, up to the prolonged physical exertion requirement of 6000 calories, or even more, per day. The average daily need is about 3000 calories.

It is obvious in instances of loss of weight, loss of strength, and lack of growth of children, that the age and life habits must be considered by the physician, and the diet of the individual must be carefully studied before a decision is made as to the change of food required. Also in cases of overweight and malmetabolism the same investigations must be made, and the diet modified according to its defects. The babe must have a properly balanced diet not only for his present health, good digestion, and immediate proper growth, but also to insure future normal endocrine gland activity, proper growth and health of his hair and teeth, and the normal development of puberty.

Hunger sensations are due to contractions of the stomach. Smoking, sweets, water, and disagreeable odors just before meals inhibit appetite. Mental depression stops appetite. The sight and smell of good food, or even the thought of palatable food stimulates the gastric secretions and promotes appetite. Good cheer promotes appetite and digestion. Generally the desire for a certain kind of food or a craving for that food in health represents a body need for nutriment of that character. Of course this does not mean that the desire for such food as appeals to the child's eye is a good indicator of what he really needs.

There is much over-eating of protein food, but not to the extent of former days. The causes of the smaller amount of protein intake are many, namely: civilization; education; higher art of cooking; less hardship; more variety of food; the greater recognition that large amounts of protein do not increase energy but rather decrease it; the increase of diseases of the organs of elimination which make end-products of protein

metabolism difficult of excretion; and, finally, the relatively high cost of animal protein foods. All of these causes have played important parts in the diminished consumption of protein, and especially of animal protein, foods.

The amount of protein foods required and its character, animal or vegetable, depends largely upon the climate. The colder the climate, the more the animal proteins and fat required; the warmer the climate, the less proteins, especially animal proteins, required, and the more fruit acids needed.

The protein of tissues is a fixed part of the body, and it is changed and lost from the body very slowly. Carbohydrates do not become a part of tissue, unless the stored glycogen may be so considered.

It has been estimated that an adult weighing about 150 pounds, working moderately eight hours a day, requires a minimum of 100 to 120 grams of protein, about 50 grams of fat, about 500 grams of carbohydrate, 2 quarts of water, and frequently takes about 12 grams of sodium chloride, a day. It is not wise for the intake of the individual to be too close to the minimum; it is better for him to have a daily reserve, even if the extra food is not required. If one type of food is diminished, generally the other types should be increased.

PROTEINS

An active man requires from 100 to 120 grams of protein per day. A protein is a food that contains not only the ordinary elements carbon, hydrogen and oxygen, but also nitrogen. Roughly they contain about 50 per cent. of carbon, about 16 per cent. of nitrogen, about 23 per cent. of oxygen and a little sulphur. There are animal proteins and vegetable proteins, and although some races live and thrive on the latter, and some diseased conditions are improved by a total abstinence from animal protein, nevertheless, man in most climates remains in better, sturdier health, and is better able to withstand disease on a properly balanced mixed protein diet.

However, it may be a fact, though not yet demonstrated, that a child, in this climate for instance, who has been brought to adult life without ever having had animal protein (meat,

fish, and poultry) may be as equally fitted to enjoy health and withstand disease as is the individual who has eaten meat throughout his life. It should be emphasized that, on account of the inherited and acquired ability to metabolize animal proteins, there must be many changes in the body for it to adjust itself to as efficiently metabolize vegetable proteins to the needs of the system, when a radical change is made from animal to vegetable proteins. Such a change may be likened to changing the fuel of a furnace from hard to soft coal without changing the grates, drafts, and the frequency and amount of fuel given the furnace. The necessity for the above caution against radical changes in diet must be recognized when we know that the amino acids of animal and vegetable proteins are not alike in proportion even if they are in kind, and V. C. Vaughan says that "a man with a perfect digestion absorbs the nitrogen of his food as amino acids."

It would lead too far afield to discuss or name the various kinds of proteins, except that it is of interest to clinicians to note that those containing nucleic acid (nucleoproteins) are the ones that yield the purins (xanthin, etc.), and phosphoric acid. It is this group of proteins, nucleoproteins, that should be removed from the diet in conditions of uric acid retention. These nucleoproteins, cellular proteins, represent the cell nuclei of tissues. Hence the protein foods that contain a large amount of small cells (the glandular organs) also contain a large amount of nucleoprotein.

It should be noted that students of nutrition find no great difference except in the fat content, and therefore in the speed and ease of digestion, between red meat and white meat, or between meat, fish and chicken. Veal is laxative to many people. One gram of protein has an energy value of four calories, and meat causes heat to be produced by the body, probably because it awakens a large amount of glandular and chemical activities. Hence cold, flabby people should eat

more meat.

A much used name for protein foods is "nitrogenous foods," because they contain nitrogen. Most of these proteins are very complex bodies, comprising many amino acids, and each protein

must be digested into its component parts ("bricks" as Lafayette B. Mendel terms them) before it can be absorbed and circulate in the blood. About eighteen amino acids have been recognized. Each part of the body will select from the blood and lymph the nutritive fragments that it needs for its activity, growth, reconstruction and up-keep.

Most proteins are split up into amino acids in the intestines, and absorbed as such. The most important sources of proteins are meat, fish, poultry, eggs, milk, cheese, wheat, beans, peas, and oats. Meat, fish, eggs, and milk contain the protein elements necessary for body growth and up-keep. Casein is the principal protein in milk. A large part of the protein of wheat, gliadin, is not a very valuable protein food. Gelatin is a protein, and nuts furnish a valuable source of protein for food. Cooked beef contains from 22 to 30 per cent. or more of protein; lamb about 20 per cent.; and mutton more than lamb; turkey about 28 per cent.; chicken about 18 per cent.; fish from 21 to 26 per cent.; oysters and clams about 6 per cent.; boiled eggs about 13 per cent.; cheese about 26 per cent. ; peas about 25 per cent.; peanuts about 26 per cent.; pine nuts about 34 per cent.; almonds about 21 per cent.; English walnuts about 16 per cent.; Brazil nuts about 17 per cent. Fish is a valuable protein food, and the oily varieties represent high caloric value.

The approximate time, in a healthy individual that it takes to digest proteins is as follows: beef requires from 3 to 4 hours; mutton about 3 hours; lamb about 211⁄2 hours; boiled fish 11⁄2 to 21⁄2 hours; boiled ham 2 to 3 hours; raw oysters 2 hours; sweetbreads 2 hours; poultry 22 to 4 hours; goose 4 to 5 hours; milk 2 hours; hard boiled eggs 3 to 31⁄2 hours; cheese 3 to 4 hours. However, the stomach digestion of meat varies in its duration in different individuals, there being two types, the slow and the fast, and it does not make much difference as to the manner of cooking the meat. If the digestion is normal, the stomach should be empty in 3 to 4 hours.

Briefly, the digestion of proteins means a change largely to proteoses and peptones in the stomach, and a further splitting in the intestine to amino acids. Underhill' says that such 1 The Physiology of the Amino Acids, F. P. Underhill.