THE NUTRITIONAL VALUE OF SOME COMMON CARBOHYDRATES, FATS, AND PROTEINS STUDIED IN RATS BY THE SINGLE FOOD CHOICE METHOD

Abstract

Reared on a standard food mixture until an avg. age of 64 days, rats were then restricted to water and a single purified (or nearly purified) foodstuff including 7 carbohydrates, 9 fats, and 10 proteins. The survival time, activity, etc., were taken as a measure of the nutritional value. Among the carbohydrates the greatest appetite was for starch, glucose, and sucrose; of the fats, for butter, olive oil and lard; of the proteins, for desiccated blood fibrin and casein. The smallest appetite was for lactose and galactose, for perilla oil and glycerine, and for zein, lactalbumin, and gelatin. The rats lived longest on glucose (57 days); butter kept them alive 53 days, and casein (enzyme digest) 47 days. For the carbohydrates and fats the food intake bore a direct relationship to survival time, but not for the proteins; on these the rats lost wt. somewhat more rapidly than on the carbohydrates and fats during the 1st 10 days, later at about the same rate on each of the 3 foodstuffs. Activity was greatest on the carbohydrates, less on the fats, and least on the proteins. Most of the rats showed diestrous vaginal smears almost immediately when placed on the single food choice diets. Rats on fats or carbo-hydrates, drank comparatively small amts. of water, except those on galactose and glycerine, which drank very large amts.; rats on proteins drank normal amts. The results indicate that in usual expts. with mixtures of synthetic or natural foods the appearance of pathological symptoms depended more on the eating of too much of certain substances, rather than too little.