Dose response to a dietary oat bran fraction in cholesterol-fed rats.
The two objectives of this research were to improve the cholesterol-fed rat as a model for evaluating the hypocholesterolemic potential of foods and to determine the relationship between serum and liver lipid levels in the cholesterol-fed rat and the ingestion of nine levels of a high fiber oat flour (HFOF) derived from oat bran. Ingestion of 0.2% cholic acid, sodium cholate or sodium taurocholate with 1% cholesterol (CH) significantly elevated serum and liver CH, liver triglycerides and liver weight compared to those values in control rats fed diets not containing CH and bile acids; 0.05 and 0.1% cholic acid with 1% CH were also effective. Ingestion of increasing amounts of HFOF, containing 0-10% dietary fiber, by rats made hypercholesterolemic with 1% CH and 0.1% cholic acid in the diet produced a significant inverse relationship between serum and liver cholesterol levels and HFOF intake; r = 0.48, p less than 0.0001 for serum CH and r = 0.55, p less than 0.0001 for liver CH. Because of the similarities in the responses of humans and of the cholesterol-fed rat to oat fiber ingestion, this dose-response relationship in the rat model suggests that larger intakes of soluble oat fiber sources may be accompanied by greater reduction in serum CH levels in humans.