This section is from the book "A Treatise On Therapeutics, And Pharmacology Or Materia Medica Vol2", by George B. Wood. Also available from Amazon: Part 1 and Part 2.
Antiphlogistic Diet. Three conditions are essential to the constitution of a strictly low diet, adapted for full antiphlogistic effect; first, that it must be feebly nutritive; secondly, that it must not have the effect, through its difficult solubility in the stomach, or any other quality, of irritating the digestive organs; and thirdly, that it should not be stimulating to the system. In relation to the first of these conditions, there should be a scale rising from the lowest point nearly up to the standard of health, in order that it may accord with the varying degree of systemic excitement; in relation to the second, the character of the food may be changed with the increasing digestive power; but, so long as a positively sedative influence is required there must be no relaxation upon the third point. For the sake of convenience, we may make four degrees of low diet, rising successively from the lowest; though in reality they run together by insensible gradations.
a. The diet lowest in the scale of nutrition consists of a set of vegetable principles, not analogous in composition to any one of the proper constituents of the animal tissues, and therefore requiring change before they can enter into the nutrition of the body. They are, moreover, very bland in their nature, so as to admit of contact with the irritated tissues, without in general aggravating, in any degree, the existing irritation. They can be readily isolated, and therefore administered without admixture of substances which may be less mild. In watery solution, they are admirably adapted to the highest state of inflammatory and febrile excitement, and should be the first substances used upon commencing a nutritive plan after entire abstinence. The substances referred to are the different kinds of gum or mucilage, starch, and sugar. In composition they resemble one another closely, consisting of carbon, hydrogen, and oxygen, of which the two latter principles are in the same proportion as in water. They differ somewhat in their degree of blandness; gum being first in this respect, then starch, and lastly sugar. The blandest are best adapted to the highest grades of gastric irritation. I shall have occasion to notice these substances more particularly when treating of the class of demulcents. Those most used in this country are gum arabic, infusions of slippery elm bark and sassafras pith, arrowroot, sago, tapioca, barley-water, rice-water, refined sugar, and molasses. They are given in solution, and more or less concentrated, according to the amount of nutrition required. They may be administered separately or mixed, and may often be advantageously flavoured with one of the milder vegetable acids, especially citric acid in the form of lemon-juice. These acids themselves undergo digestion, and probably, like the principles mentioned, contribute somewhat to nutrition, or to the purposes of respiration; while, by their sedative or refrigerant properties, they directly meet the existing indication. They are occasionally, however, somewhat irritant to the stomach, and require attention on this point. They exist in fruits, from which they are usually prepared for use, in the form of expressed juice, infusion, jelly, or syrup; as in lemonade, orangeade, infusion of tamarinds, apple-water, currant jelly or blackberry jelly diffused in water, etc. in the same state of system, patients may be allowed to suck the juice of sweet oranges, and the finer kinds of grapes, which are often extremely grateful.
Some chemical physiologists deny the possession of nutritive properties by the above substances, maintaining that they are of use simply by furnishing materials for combustion in the body, and thus supporting animal temperature. Their conclusions are mainly theoretical; but have been supported by the asserted fact, that animals, confined exclusively to one of these principles, die in the course of four or five weeks. But this is true of any other single principle, however nutritious, with the exception, as has been asserted, of gluten. Fibrin, albumen, or gelatin, if given separately and exclusively to dogs, will not support life long. Hence, it is not the want of nutritious properties in gum, starch, and sugar, which causes animals to perish if confined to any one of them, but the fact that a mixture of principles, with the exception above referred to, is necessary to life. Besides, the fact that animals will live a month or more on one of them shows that it has some degree of nutritive property. it is said that they contain no nitrogen, and therefore cannot be converted into nitrogenous tissue. The answer to this is extremely obvious. Nitrogen is supplied by other bodies at the same time; and it is not impossible that, in the digestive laboratory, the nitrogen always taken into the stomach in small proportion in the water drank, and a portion of that inhaled into the lungs, may be made use of to supply the deficiency. There is no satisfactory proof that what is here suggested does not take place; and probability is altogether in its favour. Philosophers, speculating in their closets, are apt to look at the small facts brought immediately before their notice in experiments, and do not sufficiently look abroad at the great facts presented to them in nature. in respect to starch, we are told that, in the shape of sago, it serves as the chief nutriment for whole tribes of people in the East India islands; and the fact is notorious, that many millions of the inhabitants of the tropics live almost exclusively on rice, of which 85 per cent. is starch. Now in these hot regions, little animal temperature is required to be generated; as the heat of the climate is often greater than that of the body. if starch, therefore, is intended only to serve the purpose of generating heat in the body, it must be in these countries very nearly superfluous; and yet it constitutes 85 per cent. of the food of the people. is it possible that nations would adopt, as their main article of diet, a product of which so large a proportion is superfluous ? To my mind it seems quite clear, that the starch in rice enters into the constitution of the body, and aids in the formation even of its nitrogenous ingredients; and, until the possibility of this fact is disproved, a sound induction seems to me to require its admission. Besides, we have analogous facts in relation to the other principles. The Africans, when they collect gum arabic for commerce, are said to form of it a prominent article of diet, and to be well nourished under its use; and the negroes of the sugar plantations are asserted to grow fat upon the saccharine matter which they consume, at the period of the sugar harvest. At all events, long experience has convinced the medical world that patients, in febrile and inflammatory diseases, are sufficiently supported by these mucilaginous, amylaceous, and saccharine drinks, during the highest stage of excitement; and they are still used, and probably will continue to be used, whatever speculative opinions may be entertained upon the subject.