title: Dietary stearic acid alters gallbladder bile acid composition in hamsters fed cereal-based diets.
abstract: Dietary stearic acid (18:0) lowers plasma and liver cholesterol concentration by reducing intestinal cholesterol absorption. We tested the hypothesis that dietary 18:0 reduces cholesterol absorption by altering hepatic bile acid synthesis and gallbladder bile acid composition. Male Syrian hamsters were fed modified NIH-07 open formula diets, enriched (5 g/100 g diet) in one of the following fatty acids: 18:0, palmitic acid (16:0), trans fatty acids (18:1t), oleic acid (18:1c) or linoleic acid (18:2). After 18 wk, gallbladders were removed and bile acid composition determined by HPLC. The distribution of primary bile acids (mol/100 mol) was unaffected by treatment. In contrast, dietary 18:0 significantly reduced the proportion of hydrophobic secondary bile acids, resulting in a lower hydrophobicity index of the bile. These data suggest that reduced cholesterol absorption by dietary 18:0 is due, at least in part, to reduced cholesterol solubility. The data further suggest that 18:0 may have altered the microflora populations that synthesize secondary bile acids. Although cholesterol 7alpha-hydroxylase (CYP7A1) activity was significantly higher in hamsters fed 18:0 compared with 16:0, this finding is most likely due to increased fecal bile acid output in the 18:0 group rather than transcriptional regulation of CYP7A1 by 18:0 or specific bile acids.
mesh_terms: D000818:Animals; D001647:Bile Acids and Salts / Q000032:analysis*; D002784:Cholesterol / Q000378:metabolism*; D002790:Cholesterol 7-alpha-Hydroxylase / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D006224:Cricetinae; D004041:Dietary Fats / Q000008:administration & dosage* / Q000494:pharmacology; D002523:Edible Grain; D005243:Feces / Q000737:chemistry; D005704:Gallbladder / Q000201:enzymology / Q000378:metabolism*; D007408:Intestinal Absorption / Q000502:physiology*; D008099:Liver / Q000201:enzymology / Q000378:metabolism; D008297:Male; D008647:Mesocricetus; D011897:Random Allocation; D012995:Solubility; D013229:Stearic Acids / Q000008:administration & dosage* / Q000494:pharmacology
chemical_list: D001647:Bile Acids and Salts; D004041:Dietary Fats; D013229:Stearic Acids; C031183:stearic acid; D002784:Cholesterol; D002790:Cholesterol 7-alpha-Hydroxylase