A manual of practical hygiene for students, physicians, and health officers / by Charles Harrington.

  • Harrington, Charles, 1856-1908.
Date:
1911
Catalogue details

Licence: Public Domain Mark

Credit: A manual of practical hygiene for students, physicians, and health officers / by Charles Harrington. Source: Wellcome Collection.

Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.

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    physiological values as nutriment. Rubner* determined the calori- metric value of the proximate principles as follows : One gram of proteids ^= 4.1 calories. One gram of carbohydrates = 4.1 One gram of fat = 9.3 In the system, the carbohydrates and fats are burned completely to carbonic acid and water, but the proteids leave a residue of urea incapa- ble of still further oxidation. It is estimated that the ])iiysiological value of the proteids averages only about 75 per cent, of their calori- metric value. The calorimetric value of different foods of the several classes is not to be understood as bemg exactly the same. Thus, two kinds of sugar or two kinds of fat, or two kmds of proteid have not exactly the same calorimetric values, and the figures above given are to be under- stood only as fair averages. Rubner^ has determined by actual ex- perimentation the relative calorimetric values of certain food materials, and has shown that 100 grams of fat are equivalent to 225 of syntonin, or 232 of starch, or 234 of cane sugar, or 243 of muscle fiber, or 256 of grape sugar. In other words, these several amounts of food material are isodynamic. Amount of Food Necessary. For the maintenance of a proper degree of health and strength, the individual must ingest an amount of food sufficient to meet the daily loss of nitrogen and carbon. This must necessarily vary according to circumstances, and hence no rule can be laid down to fit all cases. The best that can be done is to make certain general rules based on the amount of Avork performed, for the greater the amount of work done, the greater the amount of food required to meet the necessary consump- tion of fuel and to repair the tissues. When performing heavy labor, the naturally increased desire for food is shown j)articularly in the direction of fats, and secondarily of proteids. For many years Voit's esthnate, that a man of 154 to 165 pounds, working at moderately hard labor 9 or 10 hours a day, requires 118 grams of proteid, 56 of fat, and 500 of carbohydrates, the whole yield- ing 3054.6 calories, has been generally accepted as correct. Recently, however, Chittenden^ has demonstrated conclusively by experiments extending over many months, the subjects being men engaged in intel- lectual pursuits, soldiers, and athletes in training, that half the stated amount of proteids is ample for the real physiological needs of the body under ordinary conditions of life, and that a fuel value of 3000 cal- ories is not necessary, the diminution in the proteid intake requiring no additional amount of non-nitrogenous substances. Knowing the composition of a given article of food, the proteid, fat, and carbohydrate value of a given weight can easily be determined; and thus one can construct standard dietaries for the various conditions 1 Lehrbuch der Hygiene, Leipsic, 1900, p. 438. '' Ibidem, p. 430. ^ Physiological Economy in Nutrition, New York. 1904.