The combination of milk and fruit has digestive and physiological possibilities only when restricted to certain limiting conditions, such as an empty stomach, free from digestive labors; a liver with no symptoms of complications, or the absence of any other form of nourishment save the fruit in connection with the milk.
Being in itself largely a proteid, the behavior of milk in the system resembles that of any other proteid, such as eggs, meat, fish, cheese, etc., which means that in case it fails to digest, it breaks down into processes of decomposition. The difference between the proteids and straches, with regard to indigestion, lies in the fact that the latter ferments, and the former decomposes - while fruit, being at once a solvent and a disinfectant, counteracts the bacterial processes by a system of gastric house-cleaning all its own. But while fruit by its germicidal properties thus prevents bacterial invasions, it also prevents, or at least interferes with, digestion, as the gastric and intestinal secretions, required for the digestion of starches and proteids, cease to flow in the presence of fruit-acids. This action of the fruit, which in the digestion of starches and proteids proves itself a hinderance, may in its relation to the digestion of milk, become a positive aid, owing to the peculiar character of milk, which being an albuminoid, is digested neither in the mouth nor in the stomach, but in the intestine, where the fruit-acid forms a powerful help to the liver and pancreas in the processes of emulsification.
This explains at once the seeming incongruity in the relation of fruit to milk, as compared to its relation to meat, cheese and other proteids. For as already has been shown, by its power of disinfection, fruit keeps the putrifactive bacillus out of the digestive field; while on the other hand it becomes a hinderance to the digestion to the extent it inhibits or neutralizes the flow of the normal secretions demanded for a successful starch and proteid digestion. It is furthermore this very action of fruit in relation to milk, that gives rise to the sensation of successful digestion, when in fact no digestion has taken place at all. The gastric activity has been limited to a mere process of disinfection by means of which the otherwise inevitable bacterial invasion of the digestive field has been inhibited. Hence the success of the milk- and fruit-combinations is essentially of a negative quality, with its sole virtue in the prevention of a systemic poisoning, generated by itself.
But even this advantage is lost if to the milk and fruit combination is added meat, beans, bread, egg, etc., or any form of starch or proteid foodstuffs; as, in the first place, the presence of the fruit-acid in the mouth will close the glands of the ptyaline secretion, on which the starch depends for its digestion; - and, in the second place, the same acid will inhibit the secretions in the stomach of the hydro-chloric acid on which depends the digestion of the proteids. Hence, the only safe way to enjoy milk and fruit is to take them on an empty stomach, distinct and separate, with an interval of at least two hours, - the milk always to precede the fruit in the order of their consumption. This insures a well-needed acid to the liver, in its task of emulsifying the milk, so as to render it susceptible to the lacteal absorption.
The effect of a mixture of milk and meat is particularly hostile to the orderly unfoldment of the life-and health-sustaining forces of the body. Besides the general interference with the action of the digestive juices, the combination of milk with the uric acid, present in the meat, generates dangerous alkaloidal bodies, which in case of ptomain development may strike at life with the suddenness and fatality of a deadly poison.
The fate of the meat suspended in a medium of pepsin, whose disinfective properties, when divorced from hydrochloric acid, are none - and in a temperature of 97° Fahr. - is readily seen. For the ways of alimentation are two only: digestion and decomposition. If the meat is not digested and assimilated, it is turned into corruption, with its inevitable consequence of systemic poisoning. Hence, a principle in diet - ever to be held inviolable - is to avoid mixtures of milk with meat.