Influence Of Food Upon The Nervous System
( Originally Published 1913 )
Many wild animals become remarkably tame when deprived of a meat diet. Justus von Liebig noticed in Giessen a young bear that was very tame when no meat was given him, but became wild and unmanageable when again fed upon meat. Tamers of animals, moreover, make use of this fact, simply by bringing up young animals, whenever possible, entirely with-out flesh food, the animals being thus rendered quite tame, so that they are easily trained.
To a greater or less degree the same may be observed in man. It is a fact that nations that live upon a vegetable diet, and in particular mainly upon rice, as do the majority of the Chinese, the Hindoos, etc., are of a peace-loving nature. As an illustration of the converse I would like to cite the interesting example given by Captain Merker of an African tribe, the Masais, a branch of the Semites. As related, in his great work on these interesting people, by Captain Merker, whose premature removal from his scientific labors by death is greatly to be deplored, all the warriors of this brave and warlike tribe live exclusively upon meat, blood, and milk, in companies apart from the rest of the people. The Spartans ate bloody soups and rare meats as a daily food. Liebig states that carnivorous animals are more courageous and savage than the herbivorous ones, which actually become their prey.
The nations living principally upon vegetables are less prone to engage in warlike enterprises; they like quiet and peace, and are especially lacking in initiative and energy. This need not surprise us, for it is precisely the albumin, of all food substances the greatest promoter of energy, which is very sparingly represented in their aliments. It is owing to this fact that a comparatively small number of meat-eating, energetic Britishers and Dutchmen have mastered millions of rice-eating Hindoos and Malays, and that a few Belgians were able to subjugate the millions of inhabitants of the enormous Congo regions, who, with the exception of the forest-dwellers, live upon the starchy flour made from the manioc and other similar roots, and upon millet, batates, and bananas—all of them poor in albumin, save the millet, the albumin in which is, however, rather difficult to make use of. It would be incorrect, of course, to ascribe all this solely to the influence of the inferior food—the higher intelligence and achievements of civilization also play their parts. Nevertheless, the kind of food partaken of since childhood makes man, to a great extent, what he is in physique. We shall show, too, that intelligence and all mental attributes in general are greatly influenced by food.
While the nations living principally upon rice and other foods equally poor in nitrogen are lacking in energy and initiative, they possess another characteristic in which they surpass other nations, viz., their untiring capacity for work. When a meat-eater has a heavy load to carry, he soon becomes overheated, perspires, and very soon grows tired. It is quite otherwise with the carbohydrate-eating vegetarian, who does not suffer in the same way,—a fact which I have myself tested by experimenting with various kinds of food. The ability to work is maintained through combustion of the carbohydrates, and the vegetarians are able, as we shall later explain more fully, to continue certain kinds of work, such as marching, rowing, etc., much longer than meat-eaters, without being so fatigued, even after a very long period of activity. We shall also relate almost incredible feats performed by the Congo negroes and other vegetarian tribes. One example may, how-ever, here be mentioned : As the troops of Tippo Tipp were being annihilated, a Congo negro carried the joyful news in a letter from Lukungu to Matadi in one day, a distance of 100 kilometers, and another negro carried the letter on from Matadi to Leopoldsville, another stretch of 100 kilometers, also in one day. When we consider that this was over un-trodden roads, not in any way to be compared with ours, and, furthermore, remember the tropical temperature, which, while it does not particularly affect the Congo natives, must nevertheless be taken into account, the feats just mentioned must be regarded as most remarkable.
Another advantage of a diet largely vegetarian lies in the fact that nervousness is, in general, less prevalent among people living upon such food than in those who are meat-eaters. In this respect there exists a certain inferiority in the meat-eating European, as compared with the Orientals and other vegetarian nations, who look down upon the Europeans on this account, and have but little consideration for them.
Foods may influence the nervous system through the intermediary of the blood supplied to it. Deterioration of food or the presence of injurious substances therein may generate certain toxic products in the blood, thus giving rise to an inflammatory condition, a toxic neuritis. Certain substances contained in meat stimulate the nervous system, the extractives, for instance. Taken in large quantities, these may exert an irritating effect, either directly or by affecting the thyroid gland, which has a powerful influence upon the nervous system.
The quantity of food also plays an important rôle, as insufficiency thereof, more especially of the albumin contained therein, very greatly affects the quantity and the composition of the blood, and consequently also affects the condition of the nervous system, which is nourished by the blood. The centers of thought can only carry on their functions when well supplied with blood. When, through a diseased condition of the smaller blood-vessels and stenosis of them because of arteriosclerosis or syphilis, the centers are poorly supplied with blood, very marked disturbances of the intellect may occur. This may also take place, though in a less degree, when the blood is impoverished and also diminished in quantity owing to an insufficiency of albumin in the food. Very frequently the intellectual attainments of undernourished persons are quite different from those of the well-fed. Persons suffering from hunger may sometimes, it is true, achieve very praiseworthy results in intellectual pursuits, but necessity is here the motive power, and these same persons would most probably accomplish very much more under a generous diet. Many a neglected genius would soon make itself felt if, in the stress of need, a helping hand could be held out to it; instead, it is unfortunately left to struggle on in misery. Especially in the case of gifted children, who, like all children, require ample nourishment during the period of growth, the State should lend assistance wher the parents are needy. Such children should be well nourished and taken care of. There are plenty of industrious pupils, but those with original and ingenious ideas are very rare, and these should, in the interest of the development of mankind, not be left to starve.
That the nourishment exerts a great influence upon the quality of the intellectual accomplishments cannot be denied if we consider the difference between the products of the mind evolved under different forms of diet. It is certain that the meat-eating or, we may rather say, albumin-consuming, people have accomplished much more in the way of original and creative work than those leading a vegetarian life. The English and Americans, who are great meat-consumers, rank among the first in the field of initiative knowledge and invention. In order to illustrate the influence of food upon the intellectual activity, I should like to place side by side for comparison a young American boy of 14 years who eats meat even at breakfast and a pale, bespectacled German lad of 14. Although the American might know less of dead languages and of abstract science which he would never have any use for during his life, he would certainly surpass the other in intelligence and common sense.
Were we to ascribe the superiority of the meat-eaters, or, more precisely speaking, of those who absorb a great deal or at least a sufficiency of albumin, to the more favorable climatic conditions of the temperate zones of Europe, it might be answered that China and Japan have, for the most part, the same climatic conditions. (According to Oshima, 75 per cent. of the Japanese are almost exclusively vegetarian.) Nevertheless, science in these countries is of a more contemplative and philosophic nature. Ingenious ideas, which open out a new horizon, and which advance the progress of mankind with giant strides, do not grow upon their soil. We see, on the contrary, the achievements of European scientists being accomplished with a bee-like activity and more and more extensively developed. New ideas, as, for instance, in the medical sciences, originate principally with the Europeans, and the Japanese scholars then carry on with unflagging industry most elaborate and difficult experiments. Medicine has been enriched by the Japanese in many of its branches, but in the creative field they have as yet accomplished but little. It may be assumed, however, that this will soon be the case, inasmuch as the Japanese are now learning to take a larger amount of albuminous food ; the diet of the soldiers is especially well looked after in this respect.
In the nutrition of the central nervous system albumin also plays a role of the first importance as a distributor of energy. With an albuminous diet, meat, fish, and eggs,—such elements as phosphorus and lecithin, which are indispensable for the building up and maintenance of the central nervous system, are also introduced. With a diet of rice, however, scarcely anything of these elements is absorbed, as the rice is usually, or at least by the majority, eaten without its outer coating; and it is precisely these husks that contain the most phosphorus.
To the above remarks I would like to add, in order not to be misunderstood, that I am not contemplating an unrestrained advocacy of an overrich albumin diet. Such a one may, as I shall show later, act very injuriously in all respects. My intention is rather to show that foods containing sufficient albumin are essential for intellectual attainments, and especially so when, in our schools, great mental efforts are required of the scholars during their growing period. I consider it my duty to emphasize this fact, in view of the tendency existing at present to undervalue the importance of albumin and advise against its adequate use. In the interest of the welfare of the people this must be combated with all the means at our command. As in all the departments of pathology and therapy, so also here the principle that both too little and too much of a necessary thing are injurious is not given enough consideration; the rational course is the intermediate one.
If lime and phosphorus are indispensable for the development of the supporting bony frame, they are so nonetheless for the development and maintenance of the central nervous system. The importance of phosphorus for the body is shown by the fact that probably no other mineral is so stubbornly retained by it as this one. That the mental functions are very greatly influenced by it is demonstrated by the fact that in the conditions in which this substance is eliminated in considerable quantities, e.g., in Basedow's disease, acromegaly, osteomalacia, diabetes, and in certain phosphaturias, as in prostatitis, etc., not only does pronounced nervousness occur, but frequently also psychic disturbances, while, again, in many mental affections an increased elimination of lime and phosphorus may be observed.
When we now inquire how the increased outgo of phosphorus is occasioned in the above conditions, we must first look for the causes of the diseases mentioned. They lie, as is known, in alterations in certain ductless glands—the thyroid, the sexual glands, and the hypophysis. It follows therefrom that these glands must also have a great influence upon the metabolism of phosphorus and of lime compounds. That this is actually so is shown by the work of many investigators. It was found by Roos that the excretion of phosphoric acid is increased when preparations of thyroid gland are taken, and is, on the contrary, diminished when the thyroid gland has been removed. Scholz, also, found that an elimination of phosphoric acid amounting to more than ten times the normal quantity occurs through the intestine when thyroid gland is given to patients with Basedow's disease. The conditions existing in osteomalacia teach us that similar conditions exist in connection with the sexual glands,—a fact to be referred to again later on.
It is therefore of great importance that there should be a sufficient quantity of lime and phosphorus in the food; when there is not, alterations in the nervous system occur. Thus, Grijns, Eickmann, Axel Holst, Nocht, and Schaumann have found that when there is a deficiency of phosphorus, in man as well as in animals, a degeneration of the peripheral nerves (polyneuritis) occurs, and that animals succumb under this condition (beriberi is also caused by a lack of phosphorus in the food), while they continue to live when phosphorus is given to them in their food. According to Hulshof Pol, beriberi can be cured, and likewise prevented, by the administration of a kind of bean, the kadjang-idoe (Phaseolus radiatus). Scurvy and Barlow's disease must also stand in relation to such conditions. When we wish to supply sufficient phosphorus to our bodies, we must use for this purpose organic phosphorus, and this is best in the form of an animal food rich in nucleins. At the same time we can by a nuclein-rich meat and fish diet cause a stimulating action upon the organ which regulates the use of the phosphorus in our bodies, which we shall refer to again later on.
Besides the intelligence, many other important functions, as sleep, for instance, are influenced by the food. After a heavy meal of meat, a feeling of drowsiness comes on; the sleep, however, is of short duration, and is easily disturbed. While during sleep most of our functions are quiet and but slightly active, the digestive organs nevertheless continue their work, and when aliments difficult of digestion have been taken at the evening meal the sleep is troubled; the same is the case when there is overacidity of the gastric juice. The formation of gas is also very disturbing when food rich in cellulose, tending to produce flatulence, has been eaten.
The function of sexual potency may also be dependent upon food. An ample flow of blood to the sexual organs and the regulation of this blood-flow through the influence of the nerves play an important rôle in the maintenance of the state of potency. With poor food the sexual impulse, or libido, is but little stimulated, and the fulfillment of the act is incomplete; with overfeeding, especially with meat and certain other foods, the sexual desire may be stimulated, though the accomplishment of coitus may be correspondingly less satisfactory, owing to certain nervous influences.
The influence of food upon the temperament is of great importance. We have already referred to the fact that nations leading a vegetarian life are of a peaceful nature. Nervousness and excitability occur much more rarely than with the Europeans, and the individuals are also much better able to control themselves, and do not at once betray in their appearance every emotion or passion. The meat-eating European does not appear to good advantage beside them in this respect; he is very nervous, easily excited, and does not take the trouble to control himself ; he shows his bad temper at once. This is, however, a serious error in deportment in the eyes of the Orientals—and with perfect reason. Violence, insolent atacks, offences against the person through passion, occur much more rarely among peoples almost or entirely vegetarian than among those living upon meat. If the main objective point of progress among mankind were peacefulness and quiet, and the life in common—as in Paradise—of wild and tame animals, without mutual annihilation, an exclusively vegetarian diet would be the best way to attain this result. A quieting influence is exerted upon the mind by such a diet, and violent criminals may be subdued by means of it. It is also to be noted that if we regard criminality as a variety of disease its cure is to be attempted with food of vegetable origin. Such food is actually given in many prisons. It may, however, also have an injurious effect, for we shall show later that tuberculosis is often developed upon this basis, so that the atonement for crime in this way often becomes too inhuman. This kind of undernourishment, furthermore, is not of a nature to exert a healing and improving effect upon the disposition, for it has an injurious effect upon the nervous system and the mind. The symptoms are very often aggravated in neurasthenia, if too little is eaten or the meals are taken too far apart; cramming with food—Weir Mitchell's treatment—may here do much good. The late Professor de Smet, of Brussels, gave such patients large quantities of Iambic, an acid Belgian beer, to drink, in order to stimulate their appetites, and allowed them to eat bacon, eggs, and meat every three or four hours, until they were well fattened; the neurasthenics were nearly always benefited, and even more so hysterical women, who in fear of their nervous dyspepsia did not have the courage to eat, and were, in consequence, half-starved.
That the temperament is very frequently unfavorably influenced by undernutrition is certain. A cat which has eaten well purrs and is contented. A dog which has not had enough growls and is ready to bite. The average man, too, feels satisfied after having enjoyed a good midday meal, and is then in a good humor, Quite the contrary, however, when the repast has not been to his taste, and he gets up hungry. Then he gets surly and grumbles ; how true the English proverb is: "A hungry man is an angry man !" The same may be observed with respect to entire nations, and history shows us that hunger and need have often driven the people to revolutions, as, e.g., in the great French Revolution. Statesmen who govern a nation can most easily bring about a contented condition among the people if they aim at giving them food of good quality at low prices ; otherwise, the agitators have an easy task, and there is increasing discontent. As in the time of Rome, the people, even now, demand "panem et circenses."
Hunger and the sexual impulse constitute the driving power behind the activity of man and animals. How many crimes have been instigated by poverty and the resultant hunger ! And, yet, these instinctive forces have their good sides, like all that is bad upon earth. They incite to work. If the farmer did not fear hunger and poverty, he would not till his field, and we would be deprived of our daily bread. Without need and hunger, much of the progress of mankind, and many a discovery and invention, would have remained unaccomplished. Necessity stimulates invention. Blessed be poverty, for without poverty there would be no riches! The bad is necessary in this world, in order that the good may grow out of it.