The effect of different dietary fats on liver fat deposition.

When weanling rats are fed a ration containing 9 per cent casein with sucrose as the carbohydrate and with an adequate supply of the known lipotropic factors, fatty infiltration of the liver occurs (1, 2). The addition of 0.36 per cent of nn-threonine to the diet causes a considerable decrease in liver fat deposition but does not reduce the liver fat content to as low a level as is found in rats fed an 18 per cent casein diet. Glycine fed at a level of 1.5 per cent of the diet also causes a reduction in the deposition of liver fat when it is fed either with or without supplemental threonine. In a study of the effect of increased levels of dietary fat (3) it was found that the corn oil normally used in the diet could be increased from 5 to 20 per cent without causing any greater accumulation of liver fat. In fact, the liver fat content of rats fed the higher level of corn oil was slightly lower. The liver fat content of rats fed a low protein diet containing 20 per cent of butt,er fat was higher than that of rats fed a similar diet containing 20 per cent of corn oil. When threonine was added t’o the high fat diets, the difference between the levels of liver fat of the corn oil group and that of the comparable butter fat group was greater although the total amount of liver fat was reduced in each case. Channon et al. (4, 5), in 1936, studied the effect of different dietary fats on liver fat deposition in rats fed low protein diets deficient in choline. Adult rats were used in their work and diets containing 5 per cent of casein and 40 per cent of fat were fed. They found the highest liver fat values for rats fed butter fat and the lowest for those fed olive oil; the values for those fed coconut oil were intermediate. From a comparison of the amounts of the different fatty acids in these fats they concluded that the increased infiltration of fat was proportional to the percentage of saturated Cl4 to Cl8 acids in the dietary fat. Their work was complicated by both a very low protein intake and a