Part 9

“The sudden and complete exclusion of meat is not always desirable, unless more skill and knowledge in food matters are employed than most persons possess. On the contrary, disaster has repeatedly overtaken many who have made this attempt. Pawlow has shown that meat is one of the most, and perhaps the most, ‘peptogenic’ of foods. Whether the stimulus it gives to the stomach is natural, or in the nature of an improper goad or whip, certain it is that stomachs which are accustomed to this daily whip have failed, for a time at least, to act when it was withdrawn.

“Nor is it necessary that meat should be permanently abjured, even when it ceases to become a daily necessity. The safer course, at least, is to indulge the craving whenever one is ‘meat hungry,’ even if, as in many cases, this be not oftener than once in several months. The rule of selection employed in the experiment was merely to give the benefit of the doubt to the non-flesh food; but even a slight preference for flesh foods was to be followed.

“Under flesh foods are included all meat and ‘stock’ soups. It has been shown that although these extracts of meat contain a large amount of nitrogen, it is not in the form of proteid which can be utilized, but only of waste nitrogen which must be excreted. Apparently the sole virtue of such soups is that they supply the ‘peptogenic’ stimulus above referred to.

ANYBODY CAN APPLY THE NEW KNOWLEDGE

“The practical value of the experiment consists in the fact that any layman can apply it, with or without a knowledge of food values, though with more advantage if he possess than if he lack such knowledge. If the dietetic rules of the present experiment are followed, no self-denial as to foods is required. It is, however, absolutely necessary that there should be self-control enough to break up the habit of hurried eating to which modern civilization has brought us—habituating us, as it were, to eat against time.

“Experience indicates that appetite does not lead to a diet fixed in amount or constituents, but moves in undulating waves or cycles. The men who took part in the experiment were encouraged, after any of the symptoms which seemed to be associated with high proteid (such as heaviness, sleepiness, stiffness, or soreness after exercise, or catching cold), to cut down on their proteid and substitute fat to restrain the gastric juice. This advice was intended to make application of the theories of Folin that we usually carry a reservoir of proteid, enough to supply our needs for body-building for a fortnight. If this reservoir is exhausted, proteid starvation occurs and the body feeds on itself; if it is filled too far it overflows and causes the evils of excessive proteid. If this theory is correct, the art of eating may consist largely in maintaining a golden mean, such that the proteid reservoir is neither empty nor overflowing much. Many persons fear to reduce their proteid to the Chittenden minimum for fear of proteid starvation; but the experience of those who have tried it would seem to show that this fear is groundless, provided no violence is done to natural appetite. This may be trusted, so it would appear, to raise a warning in the form of ‘nitrogen hunger,’ before the danger point is reached.” In other words, the body will ask in the language of hunger for proteid food, if you are not eating as much as you should. Professor Fisher considers that an amount of meat equivalent to about one small chop will supply all the proteid necessary in the daily ration, since proteid is also consumed in bread, potatoes and nearly all other foods.

It might be added that one of the writers has found the remedy for continual bilious headaches in the rigid exclusion from his diet of all foods that are rich in proteids, including meat, fish, eggs, milk, cheese, peas and beans; and maintains weight and working efficiency upon such amount of proteid as he derives from ordinary breadstuffs. He has found that the craving for high proteid foods soon disappears if it is not gratified; and that the quantity of bread, potatoes, etc., which the average person would eat at dinner and supper supplies all the nitrogen which his system needs, without leaving any to cause autointoxication.

HOW DIGESTION IS ACCOMPLISHED

In order not to interrupt the narrative of the Yale experiments, we have foregone defining certain of the technical terms which it was necessary to use. It will be well, before going further, to give a simple description of the manner in which the food we eat is transformed in the body into tissue building material and energy: a process the many parts of which are grouped by physiologists under the name of Metabolism.

When you take a mouthful of food it enters on a journey through the body in which it traverses more than thirty feet of the intestinal tube before that part of it which the body cannot use is ejected; the process of metabolism begins the moment the lips touch it. The six salivary glands which are located in the mouth manufacture saliva, which flows out through numerous openings, and mixes with food as it is chewed. The saliva not only moistens the food, thus allowing it to be more easily swallowed, but it also has a most important chemical office, converting all starchy food matter into sugar, and thus performing the first and one of the most essential steps in the process of digestion.

After the food has been masticated and saturated with saliva, it passes down the throat through the gullet, which performs a peculiar muscular contraction, thrusting downward the particles of food. The conversion of the starch in food into sugar, or glucose, which is begun by the saliva in the mouth, is continued as the food passes into and down the gullet, but stops almost completely when the food once reaches the stomach.

THE WORK OF THE STOMACH

It is in the stomach, on the other hand, that most of the work of digesting the albuminoids, or proteids, of food is performed by the gastric juice. The stomach is a pear-shaped bag, that holds about three pints of material, or three-quarters of an ounce for every inch of the individual’s height. Food enters it through the gullet on the upper left hand side, just below the heart. Myriads of glands in the walls of the stomach are active in the formation of either pepsin, or an acid fluid which, when combined with pepsin, forms the gastric juice.

At the back of the stomach, partly overlapping it, lies the liver, which discharges a liquid called the bile into the alimentary canal just below the stomach. Behind the stomach, lies a large gland called the pancreas, which discharges a remarkable fluid, named pancreatic juice, into the intestine through the same opening which the liver uses for its bile. Connected with the stomach is the small intestine, which is the narrow portion of the alimentary canal, and the largest and most important of all the digestive organs. It is some twenty-five feet in length, and its walls are everywhere covered with glands which secrete and exude mucous and other fluids.

At the lower end of the intestine is the colon or large intestine which is not a digestive organ in itself, but is a reservoir in which the food is stored up for a short time, to allow opportunity for complete absorption of the digested portions.

THE ELEMENTS OF FOOD

Although there may be thousands of different dishes, and combinations of foodstuffs, fundamentally they are all closely akin, and can be all resolved into a few quite simple elements: Proteid, Carbohydrate, Fat or Mineral Salts, or combinations of these; the Proteid class having many subdivisions, and the Carbohydrates being made up of the various sugars and starches.

We also know definitely just what use the body makes of these various substances. The Proteid is the up-builder of tissue, the essential foodstuff without which life cannot exist. If we compare the human body to an engine, as nearly all physiologists seem bound to do, we may say that Proteid is like the brass, or other metal, of which the structure is composed. The various Carbohydrates and the Fats are the fuels from which are derived the energy which animates and operates the mechanism. The Mineral Salts are used to supply various important bodily needs, such as elements required by the bones, or the delicate tissue in the eyes, the enamel for the teeth, and so forth.

THE WORK OF THE DIGESTIVE JUICES

As there are five main food elements, namely, proteid, starch, sugars, fats, and salts, so also there are five main digestive fluids, the saliva, the gastric juice, the bile, the pancreatic juice, and the intestinal juice.

The saliva is an alkaline fluid that digests starch. Its work is checked by the presence of acid substances; which explains why the digestive action of saliva ceases soon after it enters the stomach. Hence the importance of giving the saliva ample opportunity to perform its function, by complete mastication, is obvious.

The gastric juice, of which about seventy ounces is formed by the stomach daily, contains in addition to hydrochloric acid, a quantity of pepsin, which with the acid dissolves all sorts of proteids or albuminous substances, like meat and eggs; and it also contains rennet, which coagulates milk. The gastric juice digests proteids by converting them into pepsin, an exceedingly soluble substance which passes readily into the blood.

The bile manufactured by the liver has the function of digesting fats. Fats are not changed chemically, as are starches and proteids. They are only broken up into particles so small that the cells of the mucous membrane can take them up and effect their removal into the blood stream.

The pancreatic juice is able to perform the work of all the three digestive fluids which we have already named. In fact, it is even more powerful than saliva in the digestion of starch, since it is able to digest raw as well as cooked starch, which the saliva cannot do. It is also able to convert proteid into peptone, as does the gastric juice; and it emulsifies fats, as does the bile.

The intestinal juice digests cane sugar, and is supposed to have a digestive influence upon all the other food elements.

The mineral salts which are taken into the body are dissolved by all the digestive fluids which we have named, some by the saliva and the juices of the intestinal tube, and others, which require acids for their solution, by the gastric juice.

Nearly all these digestive fluids are also powerful antiseptics and are able to destroy germs when the health of the body as a whole is good. The gastric juice, for instance, acts as an antiseptic, preserving the stomach contents from putrefaction during the digestive process. It is a remarkable fact that the gastric juice, although it is so essential to life, is a deadly poison, which, when introduced into the blood produces insensibility and death.

These digestive juices and organs are able completely to dispose of all the food elements which are introduced into the body, save proteid alone. The sugars and starches are either completely absorbed and oxidized, or stored up in the form of surplus fat. The oxidation or burning up of proteid, however, is never complete. There is always a certain amount of unburnable substance left behind from the processes of metabolism, which the liver and kidneys of the body have to dispose of. If only as much proteid as is needed by the body for the upbuilding of its tissue, and the repair of waste, is taken, the body can very readily handle it; but an excess of proteid is highly disadvantageous. Professor Chittenden, in his great work, “The Nutrition of Man,” has set forth in elaborate detail the process of the assimilation of proteid. It appears that there are many kinds of proteid; the proteid of eggs is different from that of meat, and that again from the proteid of beans, and so on; and human proteid is different from all. Consequently, the body is obliged to transform every kind of proteid which is brought to it. This proteid is then absorbed by the blood, and carried to the tissues, which are kept perpetually bathed in a supply of nutritive material. The taking of more proteid than is needed would not be so dangerous if it were simply passed on without being digested; nor even if it were digested and transformed, and then promptly eliminated. But what actually happens is that the new proteid taken in is passed through all the stages of assimilation, and drives out in front of it, so to speak, the proteid which has already been prepared, but has not yet been used. And the result is, of course, to throw a double strain upon the liver and the kidneys, the organs of elimination.