A MANUAL OF CLINICAL DIETETICS.
A KNOWLEDGE of the physiology of digestion lies at the root of sound practical dietetics, and although it does not come within the scope of the present work to enter into a lengthy examination of different foods and their properties, or into a detailed account of the mechanism of digestion, it may be well to advert very briefly to a few points regarding foods and normal digestion..
For the present purpose foods may be grouped as (1) nitrogenous elements (albuminoids, proteids); (2) carbohydrates (starches, sugars, &c.); (3) hydro-carbons (fats); (4) salts and water.
The proper apportioning of these different elements, with due regard to the age, circumstances, and surroundings of the individual, constitutes for healthy persons a well-balanced and economical diet. Probably, however, it very seldom happens, even in health, that an exact balance is struck between the wants of the system and the amount of food that is consumed. For example, when the dietary is full and the digestive organs are vigorous, the surplus food assimilated is stored up, and increase of body-weight takes place. Moreover, even in healthy persons some of the food taken is incompletely digested, and is thrown off in the excreta. Again, when the diet is scanty and insufficient for the needs