Fundamental Food Requirements for Growth of Rat. V. Influence of Fat in Diet. ∗

Abstract

Evans and Burr 1 have postulated the existence of a new vitamin, (F), revealed in part by subnormal growth of rats fed synthetic diets extremely low in fat, and containing sucrose as the source of carbohydrate. Although the first report of their work indicates that the casein and sucrose employed as sources of protein and energy require special purification in order to demonstrate the existence of the new vitamin, later, more detailed, reports show that little improvement is secured with commercial casein and sucrose. However, great improvement in growth is noted when fat is included in the diet or when liver or lettuce is fed in addition to the usual supplements of yeast and cod liver oil. Evans and Lepkovsky 2 have offered a partial explanation of these results in the hypothesis of a sparing action of fat on the antineuritic vitamin requirement for growth, but this view does not explain the beneficial effects of the lettuce and liver.

We present here the results of several experiments with rats fed diets containing various proportions of fat without lettuce or liver supplements. Data are given for both sexes. The casein was in all cases the highly purified product described elsewhere. 3 Commercial sucrose was used in the sugar diets. The dextrin was tapioca autoclaved at 260° F. for at least 6 hours. All the fat diets contained at least 9% butterfat, the remainder of the fat being crisco or lard. Salt mixture, either McCollum's No. 185 or Osborne and Mendel's, comprised 4% of the diets. Except for Groups No. 4 and No. 9 each rat received separately each day pure dry yeast (Northwestern Yeast Company) and cod liver oil. The daily quantity of yeast was 600 mg. for Groups Nos. 2, 3, 5, 6, 8, and 10, 400 mg. for Group No. 9, 250 mg. for Group No. 1. The quantity of cod liver oil fed was 160 mg. for Groups Nos. 2, 3, 5, 6, 8, and 10, and 500 mg. for Group No. 9.