A randomised, double- blind, cross-over study investigating the prebiotic effect of agave fructans in healthy human subjects.

P Ramnani,A Costabile,G R Gibson,A G R Bustillo

doi:10.1017/jns.2014.68

Abstract

This placebo-controlled, randomised, double-blind, cross-over human feeding study aimed to determine the prebiotic effect of agave fructans. A total of thirty-eight volunteers completed this trial. The treatment consisted of 3 weeks' supplementation with 5g/d of prebiotic agave fructan (Predilife) or equivalent placebo (maltodextrin), followed by a 2-week washout period following which subjects were crossed over to alternate the treatment arm for 3 weeks followed by a 2-week washout. Faecal samples were collected at baseline, on the last day of treatment (days 22 and 58) and washout (days 36 and 72), respectively. Changes in faecal bacterial populations, SCFA and secretory IgA were assessed using fluorescent in situ hybridisation, GC and ELISA, respectively. Bowel movements, stool consistencies, abdominal comfort and mood changes were evaluated by a recorded daily questionnaire. In parallel, the effect of agave fructans on different regions of the colon using a three-stage continuous culture simulator was studied. Predilife significantly increased faecal bifidobacteria (log10 9·6 (sd 0·4)) and lactobacilli (log10 7·7 (sd 0·8)) compared with placebo (log10 9·2 (sd 0·4); P=0·00) (log10 7·4 (sd 0·7); P =0·000), respectively. No change was observed for other bacterial groups tested, SCFA, secretory IgA, and PGE2 concentrations between the treatment and placebo. Denaturing gradient gel electrophoresis analysis indicated that bacterial communities were randomly dispersed and no significant differences were observed between Predilife and placebo treatments. The in vitro models showed similar increases in bifidobacterial and lactobacilli populations to that observed with the in vivo trial. To conclude, agave fructans are well tolerated in healthy human subjects and increased bifidobacteria and lactobacilli numbers in vitro and in vivo but did not influence other products of fermentation.

Highlights

This placebo-controlled, randomised, double-blind, cross-over human feeding study aimed to determine the prebiotic effect of agave fructans
To support the in vivo observations, we investigated the effect of agave fructans on the growth of faecal bacteria in a three-stage continuous culture system
No significant differences were observed for other SCFA produced. This is the first randomised, cross-over, double-blind clinical trial that has examined the effect of branched agave fructan on bacterial populations, SCFA, secretory IgA (sIgA), PGE2, bowel habits and mood changes in healthy human volunteers

Summary

Introduction

This placebo-controlled, randomised, double-blind, cross-over human feeding study aimed to determine the prebiotic effect of agave fructans. Agave fructans are well tolerated in healthy human subjects and increased bifidobacteria and lactobacilli numbers in vitro and in vivo but did not influence other products of fermentation. The importance of inulin-type fructans with linear β (2 → 1) linkages in human and bowel health is well established both in vitro and in vivo[3,9]. They have been consistently associated with increases in populations of bifidobacteria and lactobacilli and production of desirable fermentation endproducts[3,10,11]. Several studies have investigated linear-chain fructans[3]; there are few data available on branched-chain fructans[15]

Methods

Results

Conclusion