Fatty acid oxidation in relation to cholesterol biosynthesis in rats.

Groups of male and female rats were fed diets containing (calorie basis) 2% corn oil (low-fat, LF), 42% corn oil (CO) or 2% corn oil plus 40% beef tallow (BT) for 2 weeks. Then rats of each sex and diet group were given an intraperitoneal injection of(14)C-acetate,- stearate- oleate or linoleate. Acetate incorporation into cholesterol and rate of oxidation of each fatty acid were determined. Specific activity of cholesterol was higher in females than males, higher with 40% lipid in the diet than with 2% corn oil and higher for CO than BT. Linoleate was oxidized more rapidly than oleate which exceeded stearate. An index of dietary lipid oxidation was computed based on fatty acid oxidation rate, per cent of each fatty acid in the diet and per cent of lipid calories in the diet. Serum cholesterol-(14)C was found to be proportional to dietary lipid oxidation index.