The Varying Requirement for Choline for Normal Metabolism of Proteins (Casein, Lactalbumin, and Soy Protein) with Particular Reference to the Hepatico-renal Syndrome1,2

Abstract

Summary 1. The development of the hepatico-renal syndrome in young rats reported by others as the result of a choline or labile methyl deficiency, is confirmed. The pathological manifestations determinable by analytical methods are: Excessive deposition of fat in the liver seemingly commensurate with the degree of deficiency, increase in uric acid retention in the kidneys, sub normal riboflavin concentrations in the kidney tissue, and decreased rate of excretion. 2. The subnormal riboflavin concentration in the kidneys is seemingly a sensitive indication of impairment of kidney function. 3. Impairment of kidney function as induced by choline or choline equivalent deficiency progresses in severity in young animals during the first 8 to 12 days; a mortality rate of 50 to 100 per cent during this period is not uncommon. The condition spontaneously improves in the survivors after about the 12th to 14th day, with gradual resumption of growth. Concurrent reduction in liver fat levels do not take place, however, and may even continue to increase with time unless choline supplements are provided. 4. A daily “choline equivalent” intake of about 12 to 15 mg. is required for the prevention of the hepatico-renal or choline deficiency syndrome in young rats. 5. The amount of choline to be furnished as a supplement for the prevention of the hepatico-renal syndrome varies with the methionine intake carried by the qualitative character and quantitative level of the dietary protein. 6. Under the conditions prevailing in these experiments, dl-methionine furnished as a supplement at levels calculated to yield the same choline equivalent intake as was furnished by choline, proved to be less effective than cholineitself. 7. Choline as a supplement of low protein dietaries or diets containing protein of low methionine content furnishes readily available labile methyl, seeming essential for normal protein utilization, effecting, other things equal, a methionine sparing action in promoting growth and maintaining normal liver and kidney functions. 8. Casein was found to be superior to the other proteins tested in preventing the hepatico-renal syndrome; in maintaining normal liver function, and in preventing excessive deposition of fat in the liver.