CHEMISTRY AND PHYSIOLOGY OF DIGESTION BY WILLIAM EDWARD FITCH, M.D. MAJOR MED. RES. CORPS, U. S. A. FORMERLY LECTURER ON SURGERY, FORDHAM UNIVERSITY SCHOOL OF MEDICINE; SARY; PREFACE While much has been written of late on the subject of nutrition and dietetics, it is widely scattered through various books, journals, pamphlets, and government and scientific reports, which are not readily accessible nor sufficiently comprehensive to furnish the physician with a foundation upon which to build a practical working knowledge of the scientific application of foods in either health, or diseased conditions. Besides, much of this matter is too ultrascientific to be of practical value to the busy physician. Moreover, in actual practice the physician is often confronted with many cases where a knowledge of the approximate caloric value of foodstuffs, as well as of the proper kind and dosage, will be of far greater value to him than any knowledge of the therapeutic action of drugs. This knowledge is beginning to sprinkle down upon the students of nutrition like the plenteous showers from Heaven-too fast, indeed, for assimilation-but the excess is being collected in the reservoirs of trophotherapeutic knowledge from which only those who understand may drink intelligently. In order to understand the rationale of nutrition, a working knowledge of the chemical changes which the foods undergo in the body is necessary. Therefore the body must be regarded as a human laboratory of nicely balanced chemical reactions. This knowledge of physiological chemistry is so essential that much space is devoted to the subject in Volume I, embracing a concise presentation of the fundamental principles, including the most essential facts of physiological chemistry, with a brief but succinct description of the digestive organs, explaining the special functions of each in the process of digestion, and graphically describing the physiology of the absorption of foods. Without such a knowledge of the chemistry and physiology of digestion, many of the statements with regard to nutrition would convey but the most vague ideas to the reader. Life can proceed in a normal manner only when the body cells are supplied with a well-balanced dietary suitable for their needs. This demands a certain number of heat units or calories daily, supplied from the ternary food elements in the proper proportion of protein, fat and carbohydrate. To enable each cell in the body to maintain its proper place in |