THE NORMAL DIET
THERE are seven basic essentials of a normal diet:
1. Enough nutrition.
2. Enough protein.
3. Proper mineral salts.
4. Fresh life-giving substancescalled Vitamins.
5. Enough water.
6. The food must be reasonably free from bacterial contamination, especially certain disease-producing bacteria and parasites.
7. There should be bulk or roughage.
Let us study each of these requirements.
First, enough fuel or nutrition or energy. Your body is a kind of a machine. It requires energy to keep it going. The energy it re-quires is no different from any other kind of physical energyheat, electricity. When a muscle lifts your leg in walking it does so by using up so much energy. This energy is obtained from burning food. Especially starches, sugars and fats. Proteins, or animal foods, can, however, be used in this way.
So every diet must contain enough of these substances to keep the engine going. If no food is taken in for a time the body begins to attack its own substance and break it down. This can go on for a certain length of time only. Long starvation regimens advocated by extreme faddists are always dangerous.
How much energy do you need a day? It depends upon your age, weight and activities. A baseball player needs more than a clerk, be-cause the ball player does ten or twenty times as much muscular work. A one-year-old child needs more than an old man of eighty. The baby’s organism is keyed to a higher rate of expenditure of energy, and it kicks around more and makes more unconscious movements. If they took the same number of steps, Paul Whiteman would need more than Rudy Vallee, because when Whiteman walks up a flight of stairs he pulls up nearly twice as much weight as Rudy Vallee.
Thus weight, age and activity determine the amount of food you need.
The actual energy requirements of any person can be measured with great accuracy. The unit of measurement is the calorie. A calorie is a certain amount of heat, a certain amount of energy.
Many people have some difficulty in getting a clear mental picture of what a calorie is. Dr. Joslin has given us a definite picture of what you do when you use up one calorie.
A person weighing a hundred and fifty pounds, sitting in a chair, rises, closes the door and reseats himself. He has used up one calorie. On the average, he uses up 2400 of them a day.
What food amounts represent one calorie? One drop of cream is one calorie. Break an oblong soda cracker into four equal parts. Each is one calorie. The amount of granulated sugar you can get on the tip of a small after dinner coffee spoon is one calorie.
You take into the body one calorie when you eat a quarter of a soda cracker.
Now, how many calories do you need a day?
Even when you sleep you are using up some calories. The mere act of breathing requires some muscular movements which result in the burning of calories. While asleep or lying quietly you use about half a calorie per pound of body weight an hour. Of if you weigh a hundred and fifty poundsyou use 75 calories an hour. This is roughly 1500 calories in the twenty-four hours.
If you begin to walk around, even in the performance of the most ordinary activities, this is raised very rapidly. Most of us use at least 3000 calories a day. A football player or day laborer doubles this again.
The human body of an average adult when viewed in a cool and calculating chemical way, consists of about 97 pounds of water, about 22 pounds of albumin, 20 pounds of fat, 21 pounds of sugar, and 7 pounds of salts.
The function of food is twofoldfirst to replace these chemical compounds when they break down and, second, to keep the mechanism movingtissue replacement and energy. The interaction of these chemical elements not only makes man move around and perform certain actions that are called “work” but accounts also for such in-tangible things as the operation of his mind and soul, adding up a column of figures, falling in love, and warding off disease.
Plainly, then, a natural diet must contain basically the chemical compounds we have mentioned, or at least chemical elements which the body can build into those compounds. As a matter of practice, we take in the compounds and not the elements. In this, animals differ from plants because it is characteristic of plants that they build up their living structure out of simple elements through the action of sunlight. The body builds up and breaks down its building materials but the rate of breaking down is so slow that we need only a very small part of these chemicals in our food per day for what we call “tissue replacement.”
Energy is furnished by all classes of foods-carbohydrates, fats and protein, but mostly by the carbohydrates. The carbohydrates, which is the technical name for starches and sugars, are found in such articles of food as vegetables, fruits, bread, milk, sugar and cereals. These furnish quick energy to the body. Fat is also used almost entirely for energy but is much slower in its workings. Protein can be used for energy if necessary.
Most of our food goes to furnish energy to run the machine.
No system of diet which can lay claim to be called natural leaves out the consideration of these two fundamental factors or leaves out the chemicals which satisfy the requirements of tissue replacement and energy renewal.
Except for water, the compound which weighs the most in the body is albumin, or protein. This is the foundation of animal tissue and is present in the muscles and in all organs and tissues. It is what Huxley called “the physical basis of lifeprotoplasm.” There are 22 pounds of albumin in the body. This is broken down very slowly under ordinary circumstances and only a very small part needs to be replaced daily.
The two problems of protein in the diet are, first, how much should be taken a-day and, second, what form of protein should be used. Answering the first one, it is natural that a growing body, in infancy or childhood, will need more protein per day than the body which is stationary. Just how much the adult body, which is in nitrogenous equilibrium, requires has been the subject of a great many experiments. The object is to determine how little protein can be used and still maintain the body at its regular weight without suffering any sense of weakness or ill health.
The most famous of the experiments was that of Chittenden who chose a group of laboratory workers going about their work, and then a squad of soldiers at light gymnastic work and light duty, and, lastly, a group of university athletes at hard physical exercise. In these groups the protein content of the diet was lowered very gradually. watching the weight and nitrogenous equilibrium. Chittenden found very little difference in the protein requirements of the three groups. In other words, hard work did not raise the necessity for protein if the energy needs of the increased work were fulfilled. This latter is accomplished by liberal use of sugar, starches and fats in the diet.
Chittenden’s figures showed that for a man of average weight150 pounds, about 53 grams of protein, or something like two ounces or one-eighth of a pound (avoirdupois weight), is sufficient. This, of course, is far below what most people ordinarily take in their diet. You would get half of that in an ordinary lamb chop.
Still Chittenden’s experiment showed that people apparently function better on this amount than with the surplus which our diet ordinarily contains. A growing child requires twice as much proportionately to his weight.
The question as to what form of protein should be used divides itself into the old argument between animal and vegetable proteins. It is possible, by careful selection, to furnish all necessary protein from vegetable sources, but it is neither economic nor wise to attempt to do so. It is much better to add such animal proteins as are contained in milk or eggs, provided one’s scruples do not allow one to eat meat.
We saw in our chemical analysis of the body of a man of 150 pounds that about 7 pounds were various kinds of salts containing the elements iron, calcium, phosphorus, sulphur, potassium, chlorine, sodium, iodine, magnesium and minute amounts of copper, manganese, zinc, fluorine and silicon. About 20 to 30 grams of these minerals salts are lost by the body daily. A natural diet must, therefore, replace this loss. An average American diet for an average man contains the following amounts of these chemicals per day:
Calcium 1.9 agnesium 0.7 Potassium 6.5 Sodium 4.6 Phosphorus 2.8 Chlorine 5.8 Sulphur 2.8 Iron 0.03
Under ordinary circumstances, therefore, our diet contains sufficient replacement of the mineral salts without the necessity of worrying about it. In fact, under ordinary circumstances, our diet contains much more of certain salts than is absolutely necessary.
For instance, we probably take in about 20 grams of sodium chloride (common salt) a day. This is equivalent to a heaping table-spoonful. Not all of this, of course, is taken as salt per se. There is sodium chloride in nearly all of our foodsmilk, bread, meats, vegetables, and a good deal is added in the process of cooking. We could get along on probably 2 grams of sodium chloride a day.
The calcium content in an average diet is from 50 to 100 per cent above the minimum needs. The only element that appears to be likely to range around minimum standards is phosphorus. Sherman is of the opinion that the average American dietary is closer to the lowest phosphorus requirement than is always safe, and suggests that perhaps some cases of malnutrition are due to insufficiency of phosphorus.
Foods which contain a large amount of phosphorus are egg yolk, lean beef, cheese, wheat, beans, nuts.
Sulphur is closely linked to protein and especially muscle metabolism, and the nitrogen and sulphur excretion of the body is closely parallel, which means that sulphur leaves the body mostly in some form of protein combination. Likewise the greater part of sulphur enters the body in organic combinations, chiefly as proteins. Beef, eggs, milk, bread, oatmeal, beans, peas, and potatoes contain good amounts of sulphur.
Iron does not leave the body in very large quantities. The iron in combination in the body is broken down (i. e., destruction of red blood cells) but is re-absorbed and used again to build new cells. Thus only in the presence of hemorrhage or rapid growth is it necessary for the diet to contain a large amount of iron. In infants this has been found somewhat of a problem because milk is quite deficient in iron and infants on an exclusive milk diet may suffer from anemia in consequence.
The following table will give a comparative idea of the amounts of iron in common foodstuffs. Note the comparatively small amount in milk :
(Milligrams per 100 grams.)
Beef 3.8 Eggs 3.0 Egg yolk 8.0 Milk 0.24 Oatmeal 3.8 Bread 5.0 Beans 7.0 Spinach 3.6
A diet which provides enough energy to run the body and also provides enough protein and minerals to replace tissue waste is still not a complete diet.
Early in the nineteenth century nutritionists were trying to produce a concentrated diet which would fulfill all the body’s needs. In order to do this they had to prepare artificial food products, processing them so that they were no longer in their natural state. Sir Gowland Hopkins, Professor of Physiology at Cambridge University, pointed out that these diets which had sufficient protein, energy and salts, were still not sufficient to maintain health and growth; that they needed certain substances which were in fresh foods. These substances were later named “Vitamins.”
Six of them are known and have been named alphabetically. A. brief description of their action and where they are found is as follows:
Promotes tissue formation, growth, appetite, digestion, and pre-vents infections. Most reliable sources: Whole milk, butter, cheese, egg yolk, cod liver oil, liver from animals that are properly fed, thin. green leafy vegetables, yellow corn, spinach, yellow sweet potatoes, carrots.
Stimulates metabolic processes, protects against the disease beriberi, increases the quantity and improves the quality of milk during lactation. Most reliable sources: Whole wheat bread, rice with the. “shell” on, cereals, milk, leguminous vegetables, egg yolk.
Regulates functions of the body, promotes growth of teeth and bones, prevents scurvy. Most reliable sources: Orange juice, lemon juice, tomato juice, sprouted grains, green leafy vegetables, and milk. (when cattle are on summer pasturage.)
Regulates calcium and, therefore, bone and tooth formation; prevents rickets, promotes lactation in nursing mothers and infants. Most reliable sources: Cod liver oil, fish oils, egg yolk, whole milk, irradiated milk, Vitamin D bread.
Regulates function of reproductive organs. Most reliable sources: Green vegetables, milk, whole wheat.
Vitamin G, called in American nomenclature “Vitamin B2,” is supposed to be the vitamin which prevents pellagra. It is found in milk, yeast, green vegetables and meat.
In speaking of the fundamental requirements of a natural diet we have emphasized especially the tissue-replacing qualities and the energy-furnishing qualities, but there are some other things that a diet must do which lie outside the range of these fundamental requirements. One is that it must furnish bulk, or roughage.
A concentrated diet, or a diet in which all the food elements are in such simple forms as they are in milk, would leave in the intestines, substances which ferment and possibly intoxicate the body. I say “possibly intoxicate” because it is not certain that they will and a great deal too much has been made of this by food faddists, whose only aim has been to keep the bowels open. But good health and well being do depend upon a regular evacuation of the intestinal contents and this is best accomplished by those parts of foods which are not broken down in the process of digestion and are not absorbed. They act as a foreign body in the intestinal tube and stimulate its muscles to rhythmic movements, which result in evacuation.
The principal form in which this bulk or roughage occurs in the food is in the fiber, or cellulose, of vegetables and fruits. It is for this reason that these substances form such a desirable part and such a large part of the average dietary.
It is quite easy for anybody to estimate the percentage of bulk in his foods. Anybody can see that milk or candy contains none of it and that an apple, or cabbage, or sauerkraut contain good quantities. Celery, radishes and carrots, as is evident by the way they feel against the teeth, contain a large amount of indigestible substance. When I say “indigestible,” this is the opposite of meaning that they cause indigestion, although these are the elements which frequently aggravate a case of acid dyspepsia.
Besides the actual bulk, a great many fruits and vegetables contain in their juices chemical elements which have a slight cathartic effect. Sauerkraut juice has been proved by Gerlen to be decidedly laxative in character. The fats, by promoting the flow of bile, may act somewhat in the same way, although they contain no roughage in themselves. Probably the juices of apple and cranberry have this same sort of action.
The other element which is required in foods is freshness. No one can subsist on completely cooked or preserved foods indefinitely. This, of course, means essentially that foods must contain the vitamins, those substances which seem to promote, by their chemical action, a great many processes which keep the body in a state of well being and good health.