Background:The human colon is colonised by a dense microbial community whose species composition and metabolism are linked to health and disease. The main energy sources for colonic bacteria are dietary polysaccharides and oligosaccharides. These play a major role in modulating gut microbial composition and metabolism, which in turn can impact on health outcomes.Results: We investigated the influence of wheat bran arabinoxylan oligosaccharides (AXOS) and maltodextrin supplements in modulating the composition of the colonic microbiota and metabolites in healthy adults over the age of 60. Male and female volunteers, (n = 21, mean BMI 25.2 ± 0.7 kg/m2) participated in the double-blind, cross over supplement study. Faecal samples were collected for analysis of microbiota, short chain fatty acids levels and calprotectin. Blood samples were collected to measure glucose, cholesterol and triglycerides levels. There was no change in these markers nor in calprotectin levels in response to the supplements. Both supplements were well-tolerated by the volunteers. Microbiota analysis across the whole volunteer cohort revealed a significant increase in the proportional abundance of faecal Bifidobacterium species (P ≤ 0.01) in response to AXOS, but not maltodextrin, supplementation. There was considerable inter-individual variation in the other bacterial taxa that responded, with a clear stratification of volunteers as either Prevotella-plus (n = 8; > 0.1% proportional abundance) or Prevotella-minus (n = 13; ≤0.1% proportional abundance) subjects founded on baseline sample profiles. There was a significant increase in the proportional abundance of both faecal Bifidobacterium (P ≤ 0.01) and Prevotella species (P ≤ 0.01) in Prevotella-plus volunteers during AXOS supplementation, while Prevotella and Bacteroides relative abundances showed an inverse relationship. Proportional abundance of 26 OTUs, including bifidobacteria and Anaerostipes hadrus, differed significantly between baseline samples of Prevotella-plus compared to Prevotella-minus individuals.Conclusions: The wheat bran AXOS supplementation was bifidogenic and resulted in changes in human gut microbiota composition that depended on the initial microbiota profile, specifically the presence or absence of Prevotella spp. as a major component of the microbiota. Our data therefore suggest that initial profiling of individuals through gut microbiota analysis should be considered important when contemplating nutritional interventions that rely on prebiotics.
We would like to thank Donna Henderson for carrying out GC analysis. Thanks also to the Wellcome Sanger Institute’s core sequencing team for carrying out the Illumina MiSeq sequencing of 16S rRNA genes. The authors would also like to acknowledge the support of the Maxwell computer cluster funded by the University of Aberdeen.
HJF, SHD and AWW receive financial support from the Scottish Government Rural and Environmental Sciences and Analytical Services (SG-RESAS) and this work was partly funded by the Biotechnology and Biological Sciences Research Council (BBSRC-CASE) which supported WSFC. Cargill, R&D Centre, Europe supplied the supplements used, helped to support WSFC industrial CASE studentship, including a 3 months training placement, agreed the study design and reviewed the final version of the manuscript. JW, JP and 16S rRNA gene sequencing costs were funded by the Wellcome Trust (grant number WT098051).
- gut microbiota
- wheatbran extract
- Arabinoxylan oligosaccharides (AXOS)
- Short chain fatty acids
- Gut microbiota
- Wheatbran extract
- RANDOMIZED CONTROLLED-TRIAL
- FOOD-FREQUENCY QUESTIONNAIRE
- CEREAL ARABINOXYLANS