Fatty Livers Produced in Albino Rats by Excess Niacin in High Fat Diets: I. Alterations in Enzyme and Coenzyme Systems Induced by Supplementing 40% Fat Diets with 0.1% of Niacin

Abstract

Forty male weanling albino rats were divided into 4 groups and fed 20% casein diets of high fat (40%) or low fat (5%) content with adequate or excessive quantities of niacin. The niacin content of both the high and low fat diets was increased by supplementing the diets with 0.1% of niacin. Two control groups, one fed high fat and the other low fat, containing adequate (0.5 mg/100 g) quantities of niacin, were fed the diet simultaneously. Blood samples were collected for pyridine nucleotide determinations on the twenty-first and the forty-second day of the experiment. The animals were killed after 44 days and the livers analyzed for pyridine nucleotide concentration, fatty acid oxidase activity, and proximate composition. Results from this study indicate that excess niacin enters metabolic pathways to produce at least 2 unrelated effects, increased concentrations of pyridine nucleotides in blood and liver and increased levels of fat in the liver. The first effect occurs regardless of the level of fat in the diet, but the second occurs only in conjunction with a high level of dietary fat. The possibility that an increased consumption of niacin and fat increases the animals' requirement for choline is discussed.