THAT the intellectual capabilities of man are greatly influenced by his food is a truth which probably cannot be disputed by anyone. We see this exemplified in those aggregations of people who nourish themselves in a sparing and penurious way, and whose intelligence consequently remains of an inferior order. The natives of the Bismarck Archipelago and of the Solomon Islands furnish an instructive illustration of this fact. As Thurmwald has recently stated in the Zeitschrift für Ethnologie, they probably stand on the lowest plane of intelligence. Some of them are not even able to count up to twenty. They are so helpless that they would prefer to walk around a piece of wood happening to lie in their way than to move it away. According to Thurmwald, they show a remarkable slowness in thought association and are totally lacking in prudence or foresight. Their food consists principally of taro, a starchy flour on the order of manioc.
When, on the other hand, we consider the people who live upon an ample mixed diet, with plenty of nitrogenous foods and much meat and fishlike the English and Americanswe find them on the average of a high degree of intelligence, many of them being remarkably gifted : they are possessed of a wealth of creative ideas and practical inventions, with an initiative such as is perhaps not possessed by any other nation.
We may involuntarily ask ourselves, Does not this perhaps depend upon a difference in the food? Does not, perhaps, the quantity of nitrogen absorbed in the nourishment, which is so poorly represented in the diet of the native tribes referred to above, cause this difference? If we consider the experiments of Forster we must reply in the negative. This observer fed a dog upon meat which had been thoroughly soaked in water, together with plenty of carbohydrate and fatty foods, from which the nutritive salts had been carefully extracted. Not-withstanding the fact that the nutritious substances, strictly speaking, were not lacking in this food, a great falling off of the intelligence together with other symptoms of degeneration were noticed in this dog, although he had been having plenty of nitrogen.
Something was missing in the foodand this was the nutrient salts! We must consequently ascribe the striking deterioration in intelligence noted to the absence of the nutritive salts. The question then is: Which of the salts is responsible for this? It is evident that, in the presence of alterations of the functions of the brain, we must have to deal with a salt which exists in considerable quantities in the brain, foras has been said so often in this booklike begets like. If we wish to stimulate the activity of certain organs we mustas is done when fertilizing plantsadminister those salts which are contained in it and which it requires. The most important of these salts are those containing phosphorus and lime,especially the first named, for with it the lime content can be influenced and increased. That the amount of phosphorus contained in the brain plays an important rôle in the development of mental affections we have already mentioned. In idiocy and in dementia præcox Marie found a decrease of the phosphorus in the brain. It is a fact of the greatest importance that the portion of the brain which plays such an important part in the intellectual processes, the gray matter, yields, in the ethereal extract made from it, more phosphorus than the white; Petrowsky also found in it double the amount of lecithin. Lecithin, as is well known, produces glycerin and phosphoric acid when decomposed. Phosphorus is absorbed with lecithin, and the brain substance is rich in phosphorus and lecithin.
It is also an observation of great significance, with regard to our powers of resistance, that wherever there is an undue elimination of phosphorus nervous and even mental disturbances occur. In some cases, as, for instance, in osteomalacia, the condition can be improved by the administration of phosphorus, which has a favorable effect upon calcium metabolism. If in some instances the administration of phosphorus produces no effect, this must be attributed to the fact that, while it does act favorably in making up for the deficiency of phosphorus, another factor which is likewise of the greatest importance, viz., increased activity of the thyroid gland, which regulates phosphorus metabolism, has not been taken into account. That a pronounced lack of phosphorus in their food is responsible for the very low grade of intelligence exhibited by the natives of the Bismarck Archipelagofor their principal food, taro, contains very little of this substanceis, according to the above statements, not unlikely, just as the great intelligence of the English and Americans may be ascribed to the large amount of phosphorus contained in their food (they eat meat three times a day, together with much fish, eggs, and green vegetables). The frequency of gout also stands in relation to this diet. That food which contains the greatest amount of phosphorus is also the one which is rich in nucleinsuric acid producers. Animal foods are not only rich in these substances, but more organic phosphorus is also absorbed from them than from a vegetable diet, since in the latter the phosphorus, owing to the large lime content, is eliminated in an insoluble form from the intestine.
We must not flatter ourselves in the belief, however, that we grow in intelligence when we eat much meat, small fish, eggs, etc. The matter in question is not quite so simple. The effect as far as we are concerned would be about the same as in a bottomless barrel. We might take any amount of phosphorus, and it would simply pass through our bodies without our deriving the least benefit from it, if it were not retained by certain organs. One such organ which hasas we have already showna governing influence upon the metabolism of phosphorus is the thyroid gland. For the subject in question it is of importance to note that the intelligence of a person depends upon the perfect action of this organ, as I have already shown, in my work on “Old Age Deferred,” by means of a series of experiments. Suffice. it for me to state here that when the thyroid is degenerated the intelligence is considerably impaired, or, indeed, is entirely lacking, as in the cretin. When such individuals are treated with thyroid extract, and when a plentiful diet is also taken, the intelligence is greatly improved; in fact, wonders may be performed in this direction. I am of the opinion that thyroid treatment improves the intelligence because through its agency the phosphorus taken in with the food can be better assimilated. This opinion is undoubtedly fully justified, according to the above statement, as we know that the thyroid gland regulates phosphoric metabolism. Moreover, I have generally found evidence of a much better assimilation of phosphorus in analyzing the urine of persons treated with thyroid extract. That the metabolism of calcium is also increased is shown by the astonishingly rapid growth of previously stunted children. They develop both in body and in mind. I have also noted in adultsin myself for instance, as I state in the work already nameda very striking effect upon the intelligence, and the memory in particular, when thyroid extract was being taken. Among the cases in which I observed this effect I would like to cite that of a chemist, 35 years old, who while being treated in this way, in addition to showing various other indications of an improved memory, was able to recollect the word “Penthatlon,” which he had been trying in vain to recall during many years. The well-known experimenter with thyroid extract, Hertoghe, observed similar effects upon himself when following such a treatment.
In consideration of all that has been said above, and in Chapter I, section 2, and Chapter II, section 2, we are driven to the conclusion that the intellectual capacity of man may be increased (I) by taking as much as possible of foods rich in phosphorus, and (2) by exercising care that the thyroid gland, upon which the proper use and assimilation of the phosphorus are dependent, may be able to carry on its functions in a normal manner. According to the labors of Cronheim and Muller, Schaumann, and others, the organic phosphorus compounds are best adapted for this purposeespecially the nucleinphosphorus-containing foods, as has been shown by O. Loewi, Schaumann, and Jebbink. It is of primary importance, how-ever, that these foods be intelligently prepared, and not soaked or boiled out through overcooking at a long-continued high temperature, and in this way or by pressure, etc., deprived of their important nutritive salts. We have already shown how very harmful this is. The foods rich in phosphorus have already been mentioned.
The activity of the thyroid gland may be effectually stimulated by following certain dietetic regulations which have already been referred to. We shall merely mention here that a certain amount of meat in the diet may act in this way; roast meat is preferable to that which has been robbed of its extractives. Several other hygienic rules having nothing to do with the question of diet, and likewise the stimulation of the activity of the thyroid gland by extracts of the same gland obtained from animals, have been emphasized in our above-mentioned work. Great care must be exercised in such treatent, however, for if the thyroid gland becomes overactive much damage may be done. When, too, this gland is not functionating adequately, certain precautionary measures must be observed, for which the reader must be again referred to my work on “Old Age Deferred.”
The activity of certain other ductless glands which also greatly influence the phosphoric metabolism, i.e., the sexual glands, must likewise be regulated. When alterations have occurred in these glands, psychic disturbances will frequently be observed, as at the age of puberty, in pregnancy, and at the period of the climacteric. I would also call attention to the very frequent psychic disturbances in diseases of the ovaries, after castration, and particularly the melancholia of the castrated male, in varicocele, etc. As mentioned in my above-named work, I found a goiter coexistent in several cases of melancholia and dementia præcox, as well as alterations of the thyroid and sexual glands. This summer I had occasion to observe a very interesting case which I shall publish in detail later on. The patient was a 14-year-old French boy suffering from obesity and defective development of the testicles; he weighed 74 kg. He had the appearance of a eunuch, and his intelligence was somewhat impairedapathetic. The testicles could scarcely be felt, and there was almost no hair on the pubis or on the lip. I first treated him with thyroid, and after-ward with testicular extract. The result was surprising. The boy grew several centimeters in height, hair appeared upon his lip and over the pubis, the testicles grew larger, and erections took place at night and also during the day, while previously there had not been the slightest symptom of any sexual impulse. He was made a man ! The intelligence was developed to such an extent that he wanted to read all day long and interested himself in problems of all sorts.
That the intelligence is greatly influenced by the sexual organs has been demonstrated in our above-mentioned work, in which the inferior mental attributes of eunuchs were compared with those of celebrated men like Goethe, Victor Hugo, and others, who had a decided predilection for the fair sex. Since thus the sexual glands also exert a governing influence upon the phosphoric metabolism, we are forced to conclude that their influence upon the intellect takes place just through this action upon the phosphoric metabolism, a fact which will probably not be disputed by anyone. The hypophysis probably also exerts a considerable influence on the phosphoric metabolism, as shown by the works of Moracewsky and others. The increased intelligence cited by various authors as occur-ring when there is overactivity of the hypophysisin patients suffering from acromegalyis remarkable.
As a result of the facts submitted above and in Chapter I, section 2, and Chapter II, section 2, I am led to a therapeutic conclusion, which, owing to its astonishing reach, I advance with considerable diffidence, viz., that if certain mental diseases, in which very frequently no anatomical changes are noticeable, are caused by a more or less defective phosphorus metabolismwhich according to the above statements appears to be the caseone could, by the administration of a great deal of nuclein-phosphoric acid in the food, together with a treatment with thyroidovarian or testicular extracts, according to the nature of the casecause a very great improvement and possibly a complete recovery. Indeed, the administration of thyroid and ovarian extracts in certain mental affections has already caused a decided amelioration of the symptoms. I have myself seen such results in several cases of melancholia. When in other cases, however, no successful results were obtained, this might perhaps be ascribed to a defective diet. It seems therefore to be indicated that a considerable quantity of phosphorus be administered, together with these organic preparations. Certain cases of polyneuritis and epilepsy have lately been published in which the administration of phosphorus was attended with beneficial results. Lecithin (Buchmann) has a similar effect, as it causes the retention of phosphorus, as was shown by Slowzoff (and con-firmed by Joshimoto). Such favorable results would no doubt also occur in mental diseases, if phosphorus and organic preparations were simultaneously administered.