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The effect of L-rhamnose on gastrointestinal transit rates, short chain fatty acids and appetite regulation

Published online by Cambridge University Press:  05 October 2018

C.S. Byrne
Affiliation:
Nutrition and Dietetic Research Group, Division of Diabetes, Endocrinology and Metabolism, Faculty of Medicine, Imperial College London, Hammersmith Campus, London, W12 0NN
T. Preston
Affiliation:
Stable Isotope Biochemistry Laboratory, Scottish Universities Environmental Research Centre, University of Glasgow, East Kilbride, G75 0QF
J. Brignardello
Affiliation:
Department of Surgery and Cancer, Computational and Systems Medicine, Imperial College London, South Kensington Campus, London, SW7 2AZ.
I. Garcia-Perez
Affiliation:
Department of Surgery and Cancer, Computational and Systems Medicine, Imperial College London, South Kensington Campus, London, SW7 2AZ.
E. Holmes
Affiliation:
Department of Surgery and Cancer, Computational and Systems Medicine, Imperial College London, South Kensington Campus, London, SW7 2AZ.
G.S. Frost
Affiliation:
Nutrition and Dietetic Research Group, Division of Diabetes, Endocrinology and Metabolism, Faculty of Medicine, Imperial College London, Hammersmith Campus, London, W12 0NN
D.J. Morrison
Affiliation:
Stable Isotope Biochemistry Laboratory, Scottish Universities Environmental Research Centre, University of Glasgow, East Kilbride, G75 0QF
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Abstract

Type
Abstract
Copyright
Copyright © The Authors 2018 

It has been hypothesised that the appetite-suppressing effects associated with the consumption of non-digestible carbohydrates (NDC) could be attributed to their effect on intestinal transit rates as well as the production of short chain fatty acids (SCFA) following their microbial fermentation(Reference Slavin1). An acute elevation in colonic production of the SCFA propionate has previously been shown to reduce ad libitum energy intake and to increase plasma concentrations of the anorexigenic gut hormones glucagon-like peptide-1 (GLP-1) and peptide YY (PYY) in humans acutely(Reference Chambers, Viardot and Psichas2). The aim of conducting this pilot study was to determine the effects of the consumption of L-rhamnose, a reportedly propionate-producing compound(Reference Vogt, Pencharz and Wolever3), on gut transit times. We hypothesised that L-rhamnose would increase plasma propionate leading to a reduction in appetite, independent of changes in gastrointestinal transit times.

We used a dual 13C octanoic acid/lactose 13C-ureide breath test to measure intestinal transit times following the consumption of 25 g/d L-rhamnose, compared with inulin and cellulose, in ten healthy humans in a randomised cross-over design. In addition, breath H2 measurements, which are routinely used as a marker of colonic fermentation(Reference Morrison, Dodson, Preston and Weaver4), were collected. Gastric emptying (GE) and oro-caecal transit times (OCTT) were derived from the breath 13C data and compared with breath H2 excretion times. In addition, plasma SCFA and PYY concentrations were measured and visual analogue scales were completed by participants. Areas under the curve (AUC) were calculated using the trapezoidal rule. Data were compared between groups using one-way ANOVA.

Based on the 13C data, L-rhamnose significantly slowed GE rates compared to cellulose (effect size: mean ± SEM; 0.35 ± 0.13 h, P = 0.023) and inulin (0.30 ± 0.11 h, P = 0.023) but there was no difference in OCTT between treatments (P = 0.21). OCTT measured from breath 13C data was highly correlated with breath H2 for inulin (r2 = 0.89, P < 0.001) but not for L-rhamnose or cellulose (P = 0.63-0.77). The breath H2 data suggested fermentation of L-rhamnose occurred before it reached the caecum. L-rhamnose consumption significantly increased the AUC0−480 for plasma propionate versus cellulose (effect size: 1.36 ± 0.15 μM x min, P < 0.001) and inulin (effect size: 1.41 ± 0.13 μM x min, P < 0.001) as well as the AUC0−480 for plasma PYY versus cellulose (effect size: 9.77 ± 4.0 pmol/L x min, P = 0.037) and inulin (effect size: 16.41 ± 4.16 pmol/L x min, P = 0.003). There was no difference in subjective appetite measures between groups (P = 0.37).

In conclusion, the NDCs tested had a minimal effect on intestinal transit time. Our data suggest that L-rhamnose is partially fermented in the small intestine, despite L-rhamnose previously being considered to reach the colon intact, and that breath H2 reflects the site of gastrointestinal fermentation and is only a reliable marker of OCTT for certain NDCs (e.g. inulin). Future studies should focus on investigating the appetite-suppressing potential of L-rhamnose.

References

1.Slavin, JL. (2005) Nutrition 21(3), 411–8.Google Scholar
2.Chambers, ES, Viardot, A, Psichas, A, et al. (2014) Gut. 64, 1744–54.Google Scholar
3.Vogt, JA, Pencharz, PB & Wolever, TM. (2004) Am J Clin Nutr. 80(1), 8994.Google Scholar
4.Morrison, D, Dodson, B, Preston, T & Weaver, L. (2003) Eur J Clin Nutr. 57(8), 1017–24.Google Scholar