Effect of animal and vegetable fats and proteins on distribution of cholesterol in plasma and organs of young growing pigs.

Young, growing pigs were fed for 8 wk diets containing either soy protein isolate or ground beef as the main protein source and soybean oil or beef tallow as the main fat source to examine effects of types of dietary protein and fat on cholesterol distribution between blood plasma, plasma lipoproteins and body organs. Type of dietary protein did not influence concentrations of a) cholesterol in plasma, b) low-density-lipoprotein (LDL) cholesterol, c) high-density-lipoprotein (HDL) cholesterol or d) cholesterol in several organs of pigs. Pigs fed tallow had greater concentrations of plasma cholesterol and LDL and HDL cholesterol than did pigs fed soybean oil. Ratios of HDL to LDL were not altered by dietary fat. Cholesterol concentrations were greater in heart, skeletal muscle and viscera of pigs fed soybean oil than in those fed tallow. Plasma cholesterol varied reciprocally with cholesterol in several tissues. Thus, dietary beef and soy protein isolate had similar effects on cholesterol concentrations in plasma, LDL, HDL and organs, whether pigs consumed soybean oil or beef tallow as a major fat source. Soybean oil, however, exerted a hypocholesterolemic effect, irrespective of major source of dietary protein.

Adaptation of lipogenesis and lipolysis to dietary ethanol.

The effect of dietary ethanol on metabolic fates of glucose and ethanol, and activities of lipoprotein lipase and hormone-sensitive lipase in several tissues of miniature pigs were determined in vitro. Ethanol and glucose were used at similar rates for fatty acid synthesis in liver and brain and CO2 production in liver. Ethanol was preferred over glucose for fatty acid and CO2 production in ileal mucosal cells. Glucose was the preferred substrate for lipogenesis and oxidation to CO2 in adipose tissue and skeletal muscle, and for oxidation to CO2 in brain. Dietary ethanol decreased glucose and ethanol conversion to fatty acids in ileal mucosa and brain, respectively. Dietary ethanol had no effect on the capacity of liver, adipose tissue, and skeletal muscle to convert either glucose or ethanol to long-chain fatty acids. The capacity to oxidize ethanol, but not glucose, to CO2 in liver was increased by dietary ethanol. No dietary ethanol effect was observed in other tissues. The capacity for removal of plasma triglycerides (based on lipoprotein lipase activity) tended to increase in adipose tissue and skeletal muscle of pigs fed ethanol. Mobilization of long-chain fatty acids from adipose tissue (based on hormone-sensitive lipase activity), triglyceride concentration in plasma, and percentage of lipid in liver remained unchanged when ethanol was fed. Livers of ethanol-fed pigs, however, were larger than livers of control pigs. Our results indicate that feeding miniature pigs 21-37% of total caloric intake as ethanol causes significant metabolic adaptations of lipid metabolism in liver and ileal mucosa, but not in adipose tissue, skeletal muscle, and brain. The ethanol feeding, however, did not cause fatty livers or hyperlipidemia.