Cholesterol metabolism is altered when rats are fed either beef tallow as the only dietary fat or fat containing the lipid extracts of beef.

This study was designed to evaluate tissue cholesterol concentrations in rats fed the nonpolar component or the polar component of the lipid extracted from beef. Comparisons were made to tissue cholesterol concentrations of rats fed either whole beef or beef tallow. The nonpolar component was predominantly triacylglycerol with a fatty acid composition similar to that of the beef tallow. Rats consuming the diet containing the nonpolar component had a plasma cholesterol concentration similar to those of rats in the other treatment groups. However, their plasma HDL cholesterol concentration was significantly greater and their hepatic cholesterol concentration was significantly less than for rats fed the diet with beef tallow but not rats fed the diet with beef or the polar component of beef lipid. Rats fed the diet with the polar component had a plasma cholesterol concentration that was significantly less than that of the beef tallow-fed group but similar to those of the other treatment groups; however, their plasma HDL cholesterol concentration was not different from that of any other group. Comparing electrophoretic lipoprotein profiles among diet groups demonstrated enhanced proportions of HDL in rats fed beef or the nonpolar component rather than beef tallow. These data suggest a novel effect of endogenous nonpolar beef lipid on cholesterol metabolism, which seems to depend upon factor(s) other than properties that are similar to the properties of beef tallow, i.e., fatty acid composition and lipid polarity.