Cholic acid supplementation enhances cholesterol absorption in humans.
OBJECTIVE
Qualitative and quantitative changes in intralumenal bile acid composition may alter cholesterol absorption and synthesis and low-density lipoprotein (LDL) receptor expression. The role of cholic acid (CA) in cholesterol absorption in humans remains unclear and, thus, was examined in the current study.


METHODS
In a crossover design outpatient study, 12 adults aged 24-36 years took 15 mg/kg/day (CA) or no bile acid supplement (control) while being fed a controlled diet (AHA heart-healthy diet). A liquid meal of defined composition was given on day 14 of the diet, and lumenal samples were collected. Thereafter, cholesterol absorption and cholesterol fractional synthetic rate (FSR) were assessed by stable isotopic methods from days 16 to 20.


RESULTS
With CA treatment, bile was enriched significantly with CA (P < 0.0004) to 60.2% +/- 2.4% (mean +/- SEM) compared with 43.3% +/- 2.4% for controls. CA plus diet treatment significantly increased (P = 0.013) cholesterol absorption (72.6% +/- 2.9%) compared with diet treatment alone (60.4% +/- 2.9%). Percentage micellar cholesterol was increased by CA plus diet treatment vs. diet alone after meal ingestion (P = 0.004). Plasma total and high-density lipoprotein (HDL) and LDL cholesterol was unchanged with CA treatment.


CONCLUSIONS
Thus, enrichment in lumenal bile with CA results in an increase in cholesterol absorption, an effect potentially mediated by enhanced cholesterol solubilization in micelles.
Department of Pathology and Laboratory Medicine, University of Cincinnati College of Medicine, Ohio, USA.
Laura A
LA
Woollett
Donna D
DD
Buckley
Lihang
L
Yao
Peter J H
PJ
Jones
Norman A
NA
Granholm
Elizabeth A
EA
Tolley
Patrick
P
Tso
James E
JE
Heubi
D000042:Absorption / Q000187:drug effects; D000328:Adult; D001647:Bile Acids and Salts / Q000378:metabolism; D016022:Case-Control Studies; D002784:Cholesterol / Q000096:biosynthesis / Q000493:pharmacokinetics*; D019826:Cholic Acid / Q000494:pharmacology*; D018592:Cross-Over Studies; D004032:Diet; D005260:Female; D006801:Humans; D006903:Hydroxymethylglutaryl CoA Reductases / Q000235:genetics; D008075:Lipoproteins, HDL / Q000097:blood; D008077:Lipoproteins, LDL / Q000097:blood; D008297:Male; D008823:Micelles; D012333:RNA, Messenger / Q000378:metabolism; D011973:Receptors, LDL / Q000235:genetics
D001647:Bile Acids and Salts; D008075:Lipoproteins, HDL; D008077:Lipoproteins, LDL; D008823:Micelles; D012333:RNA, Messenger; D011973:Receptors, LDL; D002784:Cholesterol; D006903:Hydroxymethylglutaryl CoA Reductases; D019826:Cholic Acid