We have often observed that patients taking large quantities of milk daily, together with eggs and vegetables, and little meat, soon begin to look better, and sometimes even younger. We have also observed upon ourselves the great advantage of such a diet in comparison with other diets.

It is not surprising that persons using large quantities of milk daily look fresher and younger if we consider that when we take much fresh raw milk we are also taking extracts of various ductless glands, and especially of the thyroid.

It has been shown by Bang,^[290] Mossé,^[291] and others, that the internal secretion of the thyroid passes into the milk. There are, indeed, several facts which prove that thyroid secretion is contained in the milk. As we know, the iodine in our body comes mainly from the thyroid, which, of all organs, is the richest in iodine. Now there can be no doubt that iodine enters the milk, for when we give iodine to the mother it can pass, by way of the milk, into the infant. As the thyroid of the infant, or of puppies, contains very little or no colloid substance, upon which, as shown by R. Hutchison and Oswald, the quantity of iodine depends, they must receive the iodine from the maternal milk. Mario Flamini (Revue mensuelle des maladies de l’enfance, 20, 97-120), by injecting iodipin into a goat, obtained milk containing as much as 0.12 gramme iodine to the liter. Another very important fact is that children suffering from congenital myxœdema never show any symptom of this condition so long as they are taking their mothers’ milk; but as soon as they are weaned symptoms of myxœdema appear, which we must logically ascribe to want of thyroid secretion.

Another fact, upon which we would like to insist, is that when we extirpate the thyroid gland of goats or other animals, their milk contains (as shown by Professor Lanz in the case of goats) a substance which acts upon the thyroid gland, diminishing its activity. Logically, we think, we may conclude that the milk of goats with intact thyroids must contain a substance antagonistic to the substance contained in the milk of thyroidless goats. Such a substance is the thyroid secretion.

Besides thyroid secretion the milk also contains important nutritive substances, like albumin, milk-sugar, and fat; also lecithin, etc., certain ferments, and mineral matters, as lime, magnesia, iron, etc. (see, also, chapter on animal food). The valuable ferments which facilitate the digestion of the milk are, however, only contained in raw milk, and to a less extent in milk which is heated above 75° C. Behring has shown that even this temperature, if maintained as long as thirty minutes, is apt to deteriorate the milk. Pasteurized milk that is never heated above 70° C., and is cooled immediately afterward, contains a considerable amount of these important ferments. But if milk is heated to higher temperatures, as happens in boiling, the ferments are killed. It is of the greatest significance that raw milk has also the property to kill microbes to a certain extent. Thus Walter Hesse found in 1894 that the microbes of cholera died in raw milk. In experiments he has made recently with Hemp,^[292] it was shown that raw milk of certain kinds of cattle had also the property to kill the bacilli of typhoid fever. But it is of the utmost importance to remember that these bactericidal properties of raw milk are destroyed if the milk is heated to 60° C. (140° F.). These authors have found that refrigerated milk, even if it is cooled down from 70° C., does not lose its bactericidal properties.

There is a wonderful difference in the effects of boiled and raw milk. Animals, or children, never thrive so well on boiled as on raw milk. Professor Behring, of Marburg,^[293] has shown that animals fed on milk heated to a high temperature never thrive well. Calves have been reared in Marburg, or on Bohemian or Hungarian farms, on boiled milk, and others on raw milk. Experiments with hundreds of such calves have shown that boiled milk is not a suitable food for them.

In children, also, we can see the bad effects of using boiled milk. It has been shown by many authors that Barlow’s disease and rickets may be due to drinking overheated milk, especially when such milk is not fresh. Behring has now shown by experiments that when calves are fed on boiled milk they acquire rickety deformities of the bones and scorbutic conditions. The majority of the calves died from exhausting diarrhœas, just as do infants in large cities.

Thus it is evident that we should always use raw milk, and only when there is doubt as to the origin of the milk should we heat it, and then not above 60° to 70° C. (140 F.), so as not to destroy all its valuable properties. Considering the enormous importance of this question for the public welfare, it would be advisable to put all establishments for the supply of milk under the control of physicians or veterinary surgeons. As the welfare of many children depends upon the condition of the cow that is giving them its milk, cows should be kept with great care and regarded as a kind of wet nurse. Just as prisoners, or men who work all day in close and badly ventilated rooms, are apt to develop tuberculosis; so, also, are cows if they are kept in dark stables with no fresh air. Therefore cows should be let out to pasture on the meadows every day, and kept there at night if the weather permits. The milk is also improved in quality if the cow gets some food rich in proteids in addition to her grain and hay. Every cow should be tested by tuberculin injections, and if this is positive the animal should be destroyed. The milking of the cows should be done with scrupulous cleanliness. The udders and surrounding parts should be washed, and the milkers themselves should be dressed in clean white clothes, and their hands should be clean, preferably by washing them with some antiseptic liquid. Unless the cow is tubercular or otherwise sick, its milk never contains any harmful substances. As soon as it is obtained the milk should be put into an ice chest, as this is the best way to preserve it, and air should be excluded. It has been shown that milk cooled off to -16° C. does not lose its good qualities, and can be kept in fresh condition for many days.

By undergoing acid fermentation milk does not lose its valuable properties. Important substances like lecithin, iron, lime, native albumin, and valuable ferments are contained in such milk. Whey and buttermilk are also milk foods of the highest value.

Besides its contents of internal secretions, valuable ferments, and mineral matters, milk must also be considered as an ideal form of nourishment owing to the fact that it contains all the necessary elements of human food. It is the most nourishing of all foods since it contains albumin, fat, and carbohydrates, the three main elements of human food, in large quantity. Good cows’ milk contains about 35 grammes of albumin, 40 grains of milk-sugar, and 35 to 40 grammes of fat to the liter. Thus if a person takes 2 liters of milk a day, or even less, 3 to 4 eggs, a little butter and several rolls, he can live comfortably without meat. We have made an experiment on ourselves by taking 1½ liters of milk, 4 eggs, 2 rolls, and 20 grammes butter a day as our only food, and after two weeks of such a diet, with a bodyweight of 68 kilos, we felt very well, and even lost no weight at the end of the trial. We have found in our own case, and in many patients, that with one plate of meat at dinner, together with vegetables and the above diet, with cheese, it is possible to live prosperously for months and to increase considerably in weight. The rosy cheeks of persons living on such a diet are the best proof of its efficiency.

Those who do not like milk in large quantity may add a little cocoa, or a little weak coffee to it. For those whose stomachs cannot tolerate pure milk, a milk obtained by fermentation—kefir—is indicated. This can be prepared by fermenting cows’ milk with grains of kefir. It should not be fermented, for most purposes, for longer than one-half a day. By virtue of the carbonic acid which it contains it has a soothing action upon the walls of the stomach, and also promotes a better flow of gastric juice. Thus it is more easily digested than ordinary milk, whose valuable properties, however, it retains.

Milk is also of value when taken in large quantity, since it checks the formation of bacterial and toxic products in the intestine, which, as we know, is enormously rich in such products, especially after having eaten animal food, like meat. milk-sugar and lactic acid are very powerful antiseptic substances probably the best natural intestinal antiseptics of which we know. This fact is made use of by Metschnikoff in the production of his lactobacilline, by which, through the formation of milk acid, the multiplication of the intestinal bacilli can be checked, and thus, according to Metschnikoff, old age prevented to some extent (see, also, Chapters XIX and XX).

It is a very interesting fact that in countries where much of a certain kind of acid milk is used (e.g., Bulgarian “yogurth,” prepared with the aid of the Maya bacillus), there are many persons who live to be more than 100 (see Chapters VI and XIX). Some of the long-lived patriarchs whom we mention in this book, as Parr, who has lived to be over 152 years old, lived mainly on a milk diet.

In addition to the above-mentioned properties of milk, this food has also the great advantage of throwing the minimum amount of work upon those organs whose duties are concerned with the assimilation of food and the elimination of its waste products. We have already mentioned that animals whose thyroids have been extirpated can only survive if they are put on a milk diet. (Breisacher,^[294] Blum.^[295]) This shows that when the thyroid is extirpated or, what is the same thing, entirely degenerated, only milk food can be tolerated, for the poisons of other food, like meat, are normally destroyed to a great extent by the thyroid gland.

In old age there is greater or less degeneration of the thyroid gland. Just as is the case with infants, whose thyroids are not yet developed, so also old people, as a general rule, are more helpless against poisons formed by the decomposition of meat. For such persons evidently, just as for infants, milk food is the best.

Here, again, we see the similarity that exists between infancy and senility, and we realize the truth of the saying that in senility we return to childhood. That milk is the best food to keep the thyroid in good working order has been proved by the experimental researches of Fordyce.^[296]

In our opinion one of the greatest advantages of milk as a food is that it exacts for its assimilation so little work from some of our most overworked and most important organs, like the stomach, liver, and kidneys.

It is certainly a boon to an overworked stomach, which is otherwise normal, when we prescribe a diet of raw milk, which, for many persons, is more digestible than most other foods. It is a fundamental principle in the treatment of old age to give a rest to those organs of the body which are the most active. Such a rest will certainly do good to the stomach, especially in the case of heavy eaters, and will improve its vitality. The same maxim holds good for the liver and kidneys.

There is no food which, with the same nutritive content, contains so few harmful toxic products as milk. Imagine the difference between the liver or thyroid of a heavy meat eater, and those of one who has long taken mainly milk. The experiments of Chalmers Watson^[297] and of Forsyth^[298] speak volumes on this point.

Since milk food contains scarcely any products harmful to the liver, even when taken in large quantities, and considering at the same time, the antiseptic action of milk food upon the bacilli in the intestines, it is easy to understand that with such a diet little work is thrown upon the liver, and its tissues are not damaged. We have been surprised to see how well patients with liver or gall-stone trouble looked after a diet of milk and vegetables for several weeks. The importance of such a diet upon the condition of the bile passages is shown by the well-known fact that inflammation of the bile-ducts and gall-bladder can be caused by the immigration of bacilli from the intestine. It follows that with a lessened amount of intestinal bacilli, the bile passages will not be so liable to infection, and by a milk diet, especially one of sour milk, kefir, koumiss, etc., we can limit, to a large extent, the number of bacteria in our intestines. Therefore such a diet would be calculated to prevent disorders of the gall-ducts and bladder and gall-stone disease, which are so often found in elderly persons.

Milk is a food which contains scarcely any extractives. In consequence it is an ideal food for the kidneys, through which it passes without causing the least injury to these vital organs, which cannot be said of meat with its numerous extractive substances. Milk contains very little salt, which qualifies it as a most excellent food for the kidneys. Milk diet has rightly been given since the early days of medicine in kidney troubles. Since in old age there is an increase of connective tissue in the kidneys, with impairment of their eliminative capacity, on this account also milk diet is the most suitable for old persons.

In order to derive the greatest possible benefit from this most excellent food, it would be necessary to take human milk, as thus we introduce into our system the internal secretions of human ductless glands and human ferments. Such good fortune can, however, only fall to the lot of infants, and, we are sorry to say, not to all of them. Therefore we are obliged to use the milk of those animals which is next best to human milk—for example, asses’ milk. This, however, cannot be obtained easily; two pints of it would cost, in some places, about a dollar. The next best substitute is goats’ milk, which also contains ten times as much iron as cows’ milk. It is a great puzzle to us why the milk of this animal, which is richer in fat and albumin than cows’ milk, is not more used. Perhaps the main objection is the occasionally disagreeable smell, which, however, can be avoided by keeping the goat very clean. The goat is rarely subject to tuberculosis, which also is a strong argument for the use of its milk.

There can be no doubt that, for those who can stand it in large quantities, milk is an excellent aid in the fight against old age and in its treatment. As most constituents of the blood enter the milk, perhaps it is not too daring to say that drinking milk is, in a measure, drinking blood. Evidently blood contains all the internal secretions of the ductless glands as well as most valuable ferments; hence the rational prevention and treatment of old age would consist in drinking blood. There is, however, no general tendency to such bloodthirsty methods at the present time, but, maybe, it will be used in the future. But if we cannot drink blood let us drink milk, the most valuable food there is.