“Gelatin as a substitute for protein in the food”

Abstract

In a series of experiments on dogs the starvation nitrogen was first determined during fasting periods. Varying amounts of gelatin, containing from one fourth to two thirds of this amount of nitrogen were then fed, the remaining three fourths to one third of the starvation quantity being supplied in meat or other proteins. The calorific requirement of the animal, estimated from Rubner's tables, was made up in each experiment with fats and carbohydrates. Results show an equal sparing of the body-protein, whether one fourth, one third or one half of the starvation nitrogen was fed in the form of gelatin, the coincident sparing of protein by fats and carbohydrates being the same. When the coincident sparing of protein by non-nitrogenous food was increased by feeding a larger percentage of carbohydrates and less fat, the fraction of the starvation nitrogen fed in the form of gelatin could be raised to two thirds, the other one third being fed in meat. Nitrogenous equilibrium was maintained on this diet for several days.

The same result was obtained on man. The starvation nitrogen was obtained by analysis of the urine and feces during a fasting period of three days, and equilibrium was then established at this level on a mixed diet containing two thirds of the nitrogen in meat, the other one third in cereals. Then for two days the meat nitrogen was replaced entirely by gelatin nitrogen, the other one third remaining the same, and the potential energy supplied was increased from 40 to 48 cal. per kilo of body-weight by giving more cane-sugar, which served at the same time to make the gelatin more palatable. The nitrogen equilibrium was not disturbed during these two days nor on the two following days, when the diet was exactly the same as before the gelatin period.