Effects of dietary fat and fatty acids on sterol balance in hamsters.

Sterol balance studies, using both isotopic and chromatographic techniques, were carried out in hamsters fed semipurified diets to detect changes in sterol metabolism during the early period of the lithogenic stimulus. The balance studies examined animals in the first two weeks on the experimental lithogenic diets. The variables were as follows: dose of cholesterol (group 1, 0.05% vs. group 2, 0.2%); dietary fat (fatty acid) (group 2, butterfat vs. group 4, palmitic acid); source of hamster [group 2, Sasco (Omaha, NE) vs. group 3, Charles River (Wilmington, MA)]; average weight of animals (group 4, 60 g vs. group 5, 119 g). Animals in groups 1, 2, 3 and 5 maintained almost constant weight throughout the two-week balance study. Liver and plasma cholesterol levels increased in groups 2-5 with increasing dose of dietary cholesterol. The highest levels were found in group 4 (liver cholesterol, 32.7 mg/g; plasma cholesterol, 367 mg/dL). Sterol balance measurements showed that bile acid synthesis remained low (range 0.55-1.01 mg/d) for all groups regardless of the intake of dietary cholesterol (range, 3.27-20.90 mg/d). The dietary cholesterol absorbed from the intestine (range, 2.91-18.91 mg/d) was stored in the liver; this storage was reflected in the negative values for cholesterol balance for all groups (range, -0.70 to -14.97 mg/d). These studies did not reveal any correlations between parameters of sterol balance and cholelithiasis.