Guar gum consumption in regulation of enterohepatic cholesterol metabolism in pigs fed a high fat diet
This thesis investigates the hypocholesterolemic actions of guar gum (GG) by examining the expression of genes that regulate the enterohepatic circulation of cholesterol in pigs fed a high-fat control diet or the control diet supplemented with 10% GG. In comparison with the control group, GG consumption reduced intestinal cholesterol absorption by 59%, increased cholesterol loss from the distal ileum by 138%, and reduced plasma total cholesterol and low-density lipoprotein (LDL) cholesterol concentrations by 27 and 37%, respectively. Within the liver, GG consumption increased hepatic low-density lipoprotein receptor (LDLr) mRNA and protein expression, enhanced the protein abundance of the cytoplasmic precursor and nuclear active forms of sterol regulatory element binding protein 2 (SREBP2), and increased the mRNA and protein expression of hepatic ATP-binding cassette transporters G5 and G8 (ABCG5/G8) in comparison with the control group. We conclude that the hypocholesterolemic effects of GG consumption are mediated by a reduction in intestinal cholesterol absorption, a SREBP2-dependent increase in hepatic LDLr, and an enhanced cholesterol loss from the distal ileum.