Further observations on the effect of dietary caseinogen in the prevention of fatty livers

Abstract

IN one experiment of a series in which study was made of the effect of choline in preventing the accumulation and accelerating the removal of fat in the liver of the rat, Best and Huntsman [1935] observed that, when rats which already had a liver fat percentage of 10-13-5 were transferred to a diet of pure sucrose, the liver fat was further increased by some 8 % during the course of 6 days. In a comparable experiment in which the transfer was made to a diet containing 80 /o of sucrose with 20 % of caseinogen, this increase in liver fat did not occur.Assuming a daily food intake of 10 g. per animal, this experiment suggested that 2 g. of caseinogen had prevented an 8 % rise in the fat of a liver which was already loaded with fat. Best and Huntsman were unable to decide at that time whether this action of caseinogen was due to the fraction of a mg. of choline present in the diet and they pointed out in further possible explanation. of this result that caseinogen might give rise to betaines during its metabolism, since betaine itself was shown to be lipotropically active by Best and Huntsman [1932]. At the same time Channon and Wilkinson [1935] were investigating the production of fatty livers in normal animals on synthetic diets, because they had failed to obtain such livers by the use of the diet of mixed grain and 40 % fat originally used by the Toronto workers. Various considerations discussed by them suggested that the amount of the protein present in the diet might be a governing factor in fatty liver production and they concluded from a series of experiments that the amount of fat appearing in the liver was controlled by the amount of protein in the diet, irrespective, however, of any action of choline. In a criticism of these results, Best et al. [1935] drew attention to their experiment mentioned above ax4d stated that the results of their more recent unpublished experiments suggested that 1 g. of the caseinogen used by them had no greater effect on liver fat than did 0*5 mg. of choline. They further stated that, whilst the lipotropic effect of caseinogen was not to be underestimated, in their opinion the effect could be accounted for if the protein contained 0-2 or 0 3 % of choline, betaine or other substances with a similar action.Meanwhile Beeston et al. [1935] had applied their previous findings on this protein effect to a further extensive study of the "cholesterol" fatty liver with results which amply confirmed their original conclusion that the caseinogen present in the diet controlled the amount of glyceride appearing in the liver, irrespective of any action of choline. As typical of this powerful action of the caseinogen may be mentioned an experiment in which the amount of glyceride in the livers of a group of animals was reduced by 18-69 % by the extra daily 1 The substance of this paper was reported at a

Choline as a Dietary Factor

“…Best, Grant & Ridout (29) confirmed the lipotropic action of casein on the glyceride fraction of "fat" fatty livers and found that a diet which contained 30 per cent casein exerted an opti mum effect. The decrease in liver fat w'hich is obtained by increasing the dietary casein is not the result -of a corresponding decrease in the carbohydrate intake (17,29) . Fresh beef muscle extracted with alcohol was less active than casein and untreated egg albumin was essentially similar.…”

“…-Using this method of determining liver fat, a great many significant results have been obtained, but only those which have not been extended by the use of fractionation methods and those which are not to be discussed under other headings will be referred to here. It has been shown that the lipotropic action of choline is exhibited when variations in the protein, fat, and carbohydrate content of the diet are made (9,10,11,13,14,15,16,17,18,19,20,21). The deposition of liver fat resulting from the feeding of sucrose is also prevented by choline (12,13).…”

“…The lipotropic effect of 1 gm. of casein has usually been found to be equivalent to 5 to 8 mg. of choline (17,29). Channon & Wilkinson (15) noted that the amount of glyceride in the "fat" and "cholesterol" fatty livers was governed by the amount of dietary casein.…”

“…Gelatin was found to have an insignificant lipotropic activity, and this may be due, in large part, to its low methionine con tent (37). Beeston, Channon, Loach &: Wilkinson (17) reported that edestin was lipotropical1y active.…”