Indigestible Matter

The Chemistry Of Food and Nutrition
by A. W. Duncan, F.C.S.

(Page 3 of 11)

These views are now known to be wrong. A comparatively small quantity of Protein matter, such as is easily obtained from vegetable food, is ample for the general needs of the body. Increased muscular exertion requires but a slight increase of this food constituent. It is the carbohydrates, or carbohydrates and fats that should be eaten in larger quantity, as these are the main source of muscular energy. The fact that animals, capable of the most prolonged and powerful exertion, thrive on vegetables of comparatively low Protein value, and that millions of the strongest races have subsisted on what most Englishmen would consider a meager vegetarian diet, should have been sufficient evidence against the earlier view.

A comparison of flesh and vegetable food, shows in flesh an excessive quantity of Protein matter, a very small quantity of glycogen (the animal equivalent of starch and sugar) and a variable quantity of fat. Vegetable food differs much, but as a rule it contains a much smaller quantity of Protein matter, a large proportion of starch and sugar and a small quantity of fat. Some vegetable foods, nuts, contain much fat.

Investigation of the digestive processes has shown that the carbohydrates and fats entail little strain on the system; their ultimate products are water and carbon dioxide, which are easily disposed of. The changes which the Proteins undergo in the body are very complicated. There is ample provision in the body for their digestion, metabolism, and final rejection, when taken in moderate quantity, as is the case in a dietary of vegetables. The Proteins in the human body, after fulfilling their purpose, are in part expelled in the same way as the carbohydrates; but the principal part, including all the nitrogen, is expelled by the kidneys in the form of urea (a very soluble substance), and a small quantity of uric acid in the form of quadrates.

There is reciprocity between the teeth and digestive organs of animals and their natural food. The grasses, leaves., which are consumed by the herbivore, contain a large proportion of cellulose and woody tissue. Consequently, the food is bulky; it is but slowly disintegrated and the nutritious matter liberated and digested. The cellulose appears but slightly acted upon by the digestive juices. The herbivore possess capacious stomachs and the intestines are very long. The carnivore have simpler digestive organs and short intestines. Even they consume substances which leave much indigestible residue, such as skin, ligaments and bones, but civilized man, when living on a flesh dietary removes as much of such things as possible.

The monkeys, apes, and man (comprised in the order Primates) have a digestive canal intermediate in complexity and in length to the herbivore and carnivore. A certain quantity of indigestible matter is necessary for exciting peristaltic action of the bowels. The carnivore with their short intestinal canal need the least and the herbivore a much larger quantity. The consumption by man of what is commonly called concentrated food is the cause of the constipation to which flesh-eating nations are subject. Most of the pills and other nostrums which are used in enormous quantities contain aloes or other drugs which stimulate the action of the intestines.

Highly manufactured foods, from which as much as possible of the non-nutritious matter has been removed is often advocated, generally by those interested in its sale. Such food would be advantageous only if it were possible to remove or modify a great part of our digestive canal (we are omitting from consideration certain diseased conditions, when such foods may be useful). The eminent physiologist and bacteriologist, Elie Metchnikoff, has given it as his opinion that much of man's digestive organs is not only useless but often productive of derangement and disease. In several cases where it has been necessary, in consequence of serious disease, to remove the entire stomach or a large part of the intestines, the digestive functions have been perfectly performed.

It is not that our organs are at fault, but our habits of life differ from that of our progenitors. In past times, when a simple dietary in which flesh food formed little or no part, and to-day, in those countries where one wholly or nearly all derived from vegetable sources and simply prepared is the rule, diseases of the digestive organs are rare. The Englishman going to a tropical country and partaking largely of flesh and alcohol, suffers from disease of the liver and other organs, to which the natives and the few of his own countrymen, living in accordance with natural laws are strangers.

Indigestible Matter - Food is never entirely digested. As a reason against confining ourselves solely to vegetable food, it has been stated that such is less perfectly digested than animal food and that it therefore throws more work on the digestive organs. It is also urged that on this account a greater quantity of vegetable food is required. We have shown elsewhere that, on the contrary, vegetarians are satisfied with a smaller amount of food. Man requires a small quantity of woody fiber or cellulose in his food to stimulate intestinal action and prevent constipation.

It is difficult to determine how much of a food is unassimilated in the body. This is for the reason of the intestinal refuse consisting not only of undigested food, but also of residues of the digestive juices, mucus and epithelial debris. These latter have been shown to amount to from one-third to one-half of the whole of the faces, which is much more than had previously been supposed.

John Goodfellow has shown that of very coarse whole meal bread quite 14 per cent. was undigested, whilst bread made from ordinary grade whole meal showed 12.5 per cent. Such a method of analysis was adopted as it was believed would exclude other than the food waste. The experiments were made on a person who was eating nothing but the bread. It seems probable that a smaller proportion would have remained unassimilated had the bread not formed the sole food. It is advisable that wheat meal he ground as finely as possible, the coarse is not only to a less extent assimilated but apt to irritate the bowels.

Notwithstanding that fine white bread gave only 4.2 per cent. And a coarse white bread 4.9 per cent. of waste, a fine wheat meal bread is more economical as the same quantity of wheat produces a greater weight of flour richer in Protein and mineral matter. From a large number of experiments with man, it has been calculated that of Proteins there is digested when animal food is eaten 98 per cent., from cereals and sugars 8 per cent., from vegetables and fruits 80 per cent. The difference between the proportions digested of the other food constituents was much less. Although there is here a theoretical advantage in favor of animal food, there are other considerations of far more importance than a little indigestible waste. The main question is one of health.

Manchester the Vegetarian Society, 1905.