Carnivorous animals have a short alimentary canal and a smooth colon. The movement of food stuffs along this short, smooth passage is rapid. This is necessary for the preservation of the life of the animal, as undigested remnants of meat long retained in the body necessarily undergo putrefactive changes with the production of ptomaines and poisons of a dangerous character. The digestion of meat leaves little residue, hence an animal that lives chiefly on meat has but little bulk to stimulate the bowels to activity, a condition which favors the putrefaction of undigested remnants, and this by creating an alkaline condition of the intestines soon develops constipation.
A diet of fine-flour bread and meat, with the usual concomitants of the ordinary bill of fare, would be an excellent prescription for the production of constipation. Within the last century there has been an enormous increase in the use of flesh foods in all civilized countries; and the use of modern milling proccesses has become almost universal. Fine flour bread and meat form a combination that is productive of prodigious harm, not only in causing constipation, but also in depriving the bones of the lime salts which are essential for their development and maintenance. From the lack of lime salts comes decay of the teeth, and loss of the teeth leads to imperfect mastication of food.
The increased consumption of flesh, and the substitution of fine-flour bread for the wheatmeal of our ancestors, are two calamities, the evil results of which upon the health of the men and women of the present generation are incalculably great.
Within the last few years much evidence has accumulated to the effect that cow's milk is by no means the specially wholesome human nutriment that it was once supposed to be. Bunge, a great physiologist, and perhaps one of the world's greatest authorities on foods, goes so far, indeed, as to assert that many thousands of children are annually killed by feeding on cow's milk; and many persons have learned from their own observation that milk does not agree with them. Cow's milk is excellent food for calves, to which it is naturally adapted, but for many human adults it appears to behave almost as a poison. The probable cause is the very common inability to digest the casein of cow's milk. Personal observations in a very large number of cases have convinced the writer that at least one-third, and probably more than one-half, of the persons suffering from chronic disease cannot use cow's milk freely without more or less serious injury. One of the prominent symptoms arising from the use of cow's milk is the production of a condition commonly known as "biliousness". The tongue becomes coated, there is a bad taste in the mouth, the breath is foul, the bowels are inactive, and an examination of the stools shows the presence of considerable quantities of undigested casein undergoing putrefaction.
The free use of milk is unknown among savages. The writer has no doubt that the extensive use of milk, under the mistaken notion that it is a specially valuable food for adults as well as for infants, is one of the active causes of the steady increase of constipation amongst civilized people. Putrefaction of undigested casein in the colon produces an alkaline condition which paralyzes the bowel and encourages conditions by which the defecating mechanism is in various ways more or less irreparably damaged.
Pawlow has shown the importance of taste as an element in digestion. According to his experiments, the activity of the stomach begins almost immediately after food is taken into the mouth. The intensity of the gastric activity depends upon the degree of stimulation of the gustatory nerves. Cash has shown by experiments on dogs that even the smell of food produces peristaltic activity. If the food is not relished, the stomach does not produce "appetite juice", and the vigorous peristaltic movements that are essential for sound digestion, and that are equally necessary to stimulate movement of the intestinal contents all along the line, are not initiated. It must be remembered, as has been shown in a previous chapter, that the taking of food, although it has for its primary object the introduction of nutritive material into the body, is incidentally necessary as a means of setting up the strong peristaltic waves that push forward the fecal matters that have accumulated in the colon, causing them to pass through the sphincter which guards the upper entrance of the rectum, and to set up the series of automatic movements by which this waste and unusable material may be removed from the body.
In order, then, that these two prime purposes of eating - namely, the nourishment of the body, and the evacuation of poisonous material - should be efficiently accomplished, it is necessary that the food should be so inviting and stimulating to the senses which participate in the enjoyment 6f food that the digestive activity will be prompt and vigorous. A meal taken without relish and eaten as a mere matter of routine and duty does not accomplish this. A person who eats without appetite is always constipated. Even if the bowels move regularly, the discharged materials should have been got rid of twenty-four or forty-eight hours before; there is a latent constipation, the evil results of which do not materially differ in the main from those of other forms of constipation, although likely to escape attention. The bill of fare should be so varied from day to day and from meal to meal, and the food' should be of such a character, that each meal will be taken with keen relish. This is especially important for persons whose lives are sedentary, and who on this account are more likely to suffer from loss of appetite, and the constipation which is both a cause and a consequence of this difficulty.