The elements of the science of nutrition / by Graham Lusk.

  • Graham Lusk
Date:
1917
Catalogue details

Licence: In copyright

Credit: The elements of the science of nutrition / by Graham Lusk. Source: Wellcome Collection.

    55/850 (page 57)
    White Bread, Gm. White Bread Feces, Gm. Whole Wheat Bread, Gm. Whole Wheat Bread Feces, Gm. Amount dry substance 465-4 18.3 O 00 44.1 N 8.7 1.07 965 2 ■ 04 Calories 1825 82 1830 204 Pentosans 15.2 0.96 29.6 9.9 Cellulose 5-8 1.27 7.0 6.9 It is evident from this that the extra gram of N in the whole wheat bread is not serviceable in nutrition but appears as fecal nitrogen. Of the energy content of white bread 4.5 per cent, appears in the feces, and of whole wheat bread, 11.5 per cent. In other words, the loss in calories in the feces is 7 per cent, greater with whole wheat bread than with white bread. Rubner acknowledges the validity of the vitamin doctrine, but since no one lives on bread alone, he does not consider bran necessary to life, and in virtue of its waste in the intestinal tract of the human being, he advocates its use for cattle. To war bread, straw and sawdust were experimentally added in order to extend its nutritive value, and an analysis of the physiologi- cal result was undertaken. Thomas and Pringsheim,1 in Rubner’s laboratory, find that filter paper (pure cellulose) is not digested by a dog, but 22 per cent, may be digested by a rabbit and 57 per cent, by a sheep. Treatment with alkali reduced its digestibility one-half in these animals. The digestion is due to bacteria. Rubner2 gave 1000 gm. of horse meat to a dog and added 70 gm. of a dry sawdust preparation previously treated with hydrochloric acid. After giving meat alone the feces contained 1.09 gm. of N; after adding 70 gm. of sawdust containing 0.17 gm. N the fecal N rose to 2.75 gm. The cellulose was entirely undigested. The feces when meat alone was given contained 67.7 calories; after adding the sawdust which contained 260 calories the feces of the period contained 258 calories. Hence the sawdust caused an increased loss through the feces of 190 calories, or 73 per cent, of the quantity ingested. It is therefore impossible to convert wood by treatment with acid into a food capable of being utilized. Again Rubner3 tested upon men the value of fine white flour, 90 per cent., to which was added straw meal, 10 per cent., the latter 1 Thomas, K., and Pringsheim, H.: Arch. f. Physiol., 1918, p. 25. 2 Rubner, M.: Arch. f. Physiol., 1916, p. 40; 1917, p. 20.