Postprandial plasma bile acid responses in normal weight and obese subjects

Short Reports

Postprandial plasma bile acid responses in normal weight and obese subjects

C Glicksman1, D J Pournaras2, M Wright1, R Roberts3, D Mahon2, R Welbourn2, R Sherwood1, J Alaghband-Zadeh1 and C W le Roux1,4

1 Department of Clinical Biochemistry, King’s College Hospital NHS Foundation Trust, Denmark Hill, London SE5 9RS; 2 Department of Bariatric Surgery, Musgrove Park Hospital, Taunton TA1 5DA; 3 King’s College London, Strand, London WC2R 2LS; 4 Imperial Weight Centre, Imperial College London, London W6 8RF

Corresponding author: Dr C W le Roux. Email: [email protected]

Background: Bile acids can act as signalling molecules via various receptorsincluding the nuclear farnesoid X receptor (FXR) and pregnaneX receptor (PXR), and the cell surface G-protein-coupled receptorTGR5. The signalling has been implicated in the release of peptideYY (PYY) and glucagon-like peptide 1 (GLP-1), which improvesglycaemic control and energy expenditure. We investigated whethermorbidly obese subjects have altered postprandial bile acidresponses in comparison to normal weight subjects.

Method: Blood samples were taken every 30 min from 0 to 180 min followinga 400 kcal test meal. Samples were taken from 12 normal weightsubjects with a body mass index (BMI) of 23.2 (2.8) kg/m2 (median[interquartile range (IQR)]) and seven obese patients with aBMI of 47.2 (7.2) kg/m2. Fractionated bile acids were measuredon these samples using high-performance liquid chromatographytandem mass spectrometry.

Results: The obese subjects showed a lower postprandial response in totalbile acids compared with the normal weight subjects. An increaseof 6.4 (5.0) and 2.6 (3.3) µmol/L (median [IQR]) in normalweight and obese subjects was observed, respectively (P = 0.02).The difference was predominantly due to the glycine-conjugatedfraction (P = 0.03). There was no difference in the increaseof the unconjugated or taurine-conjugated fractions.

Conclusions: The decreased postprandial bile acid response in obese subjectscompared with normal weight subjects may partly explain thesuboptimal GLP-1 and PYY responses and could affect appetite,glycaemic control and energy expenditure.