914 METABOLISM. 



of weight in the body may with the addition of carbohydrates produce 

 a deposit of proteins. This is apparent from the following table: 1 



Food. Flesh. 



Meat. Fat. Sugar. Starch. Metabolized. On the Body. 



500 250 ... ... 558 - 58 



500 ... 300 ... 466 +34 



500 ... 200 ... 505 - 5 



800 ... ... 250 745 + 55 



800 200 ... ... 773 +27 



2000 ... ... 200-300 1792 +208 



2000 250 ... ... 1883 +117 



The sparing of protein by carbohydrates is greater, as shown by the 

 table, than by fats. According to VOIT the first is on an average 9 per 

 cent and the other 7 per cent of the administration protein without a 

 previous addition of non-nitrogenous bodies. Increasing quantities of 

 carbohydrates in the food decrease the protein metabolism more regularly 

 and constantly than increasing quantities of fat. ATWATER and BENE- 

 DICT 2 also found that the carbohydrates had a somewhat greater sparing 

 action upon proteins than fats. 



Because of this great protein-sparing action of carbohydrates the her- 

 bivora, which as a rule partake of considerable quantities of carbohydrates, 

 assimilate proteins readily (Voii). 



The greater protein-sparing action of carbohydrates as compared with 

 that of the fats occurs, as shown by LANDERGREN, 3 to a still higher degree 

 with food poor in nitrogen or in nitrogen starvation, in which cases the 

 carbohydrates have double the protein-sparing action as compared with 

 an isodynamic quantity of fat. This different behavior of the fats 

 and the carbohydrates is also shown in the experiments of RUBNER and 

 THOMAS 4 that on the exclusive feeding of sugar the nitrogen elimination 

 is reduced to the wear and tear quota while on the exclusive feeding of 

 fats the nitrogen requirement was about two to three times as great as 

 the wear and tear quota. 



The protein-sparing action of the carbohydrates and fats has generally 

 been studied through the one-sided feeding with one or the other of these 

 two groups of foodstuffs. The question may be raised whether the differ- 

 ence observed between the fats and carbohydrates could not also be 

 brought about by the simultaneous supply of carbohydrates and fat in 

 varying proportions. TALLQUIST S made a series of experiments on this 



1 Voit, in Hermann's Handb., 6, page 143. 



2 See Ergebnisse der Physiologie, 3. 



3 1. c., Inaug.-Diss., and Skand. Arch. f. Physiol., 14. Wimmer, Zeitschr. f. Biol., 

 57, has given further proofs of the strong protein-sparing action of carbohydrates in 

 nitrogen starvation. 



4 See Thomas, Arch. f. (Anat. u.) Physiol. Suppl. Bd., 1910. 



5 Finska Lakaresallskapets Handl., 1901. See also Arch. f. Hygiene, 41. 



