The effect of fat on the utilization of galactose by the albino rat.

In 1938 Schantz, Elvehjem, and Hart (1) reported that rats, calves, and pigs which received liquid skim milk as their sole diet excreted a considerable amount of galactose in the urine. No such excretion occurred when whole milk was fed. In studies with the rat it was found that the addition of 3 to 4 per cent of fat to the skim milk completely prevented the urinary loss of galactose, and further investigation proved the fatty acid fraction of the fat to be responsible for t,his phenomenon (1, 2). The use of various synthetic triglycerides showed that the even numbered fatty acids of more than 10 carbon atoms were effective. Compounds such as choline, glycerol, etc., were ineffective in preventing the loss of galactose. Zialcita and Mitchell (3) in 1945 concluded from studies made with synthetic rations containing lactose that fat as such had no influence on the utilization of galactose by the rat. The basal ration used consisted of lactose 48, fat 28, Salts 4 (4), and casein 20. Approximately equal urinary galactose losses were obtained when either butter fat or glucose comprised the “fat” portion of the diet. Somewhat lower excretions were found when the fat used was corn oil. The suggestion was made that corn oil might contain in the non-glyceride fraction some substance which influenced the metabolism of galactose. In the present paper more detailed data are given concerning the influence of fat on galactose utilization when skim milk or synthetic rations containing lactose or galactose were fed to rats.