Host–microbiome interactions in human type 2 diabetes following prebiotic fibre (galacto-oligosaccharide) intake

Abstract

Aberrant microbiota composition and function have been linked to several pathologies, including type 2 diabetes. In animal models, prebiotics induce favourable changes in the intestinal microbiota, intestinal permeability (IP) and endotoxaemia, which are linked to concurrent improvement in glucose tolerance. This is the first study to investigate the link between IP, glucose tolerance and intestinal bacteria in human type 2 diabetes. In all, twenty-nine men with well-controlled type 2 diabetes were randomised to a prebiotic (galacto-oligosaccharide mixture) or placebo (maltodextrin) supplement (5·5 g/d for 12 weeks). Intestinal microbial community structure, IP, endotoxaemia, inflammatory markers and glucose tolerance were assessed at baseline and post intervention. IP was estimated by the urinary recovery of oral 51Cr-EDTA and glucose tolerance by insulin-modified intravenous glucose tolerance test. Intestinal microbial community analysis was performed by high-throughput next-generation sequencing of 16S rRNA amplicons and quantitative PCR. Prebiotic fibre supplementation had no significant effects on clinical outcomes or bacterial abundances compared with placebo; however, changes in the bacterial family Veillonellaceae correlated inversely with changes in glucose response and IL-6 levels (r -0·90, P=0·042 for both) following prebiotic intake. The absence of significant changes to the microbial community structure at a prebiotic dosage/length of supplementation shown to be effective in healthy individuals is an important finding. We propose that concurrent metformin treatment and the high heterogeneity of human type 2 diabetes may have played a significant role. The current study does not provide evidence for the role of prebiotics in the treatment of type 2 diabetes.

Systematic review assessing the effectiveness of dietary intervention on gut microbiota in adults with type 2 diabetes

“…Seven studies provided detail on outcome assessors [29–34, 36] and five studies provided sufficient detail to establish the likely absence of selective outcome reporting [29, 32–35]. Overall, seven of the studies were considered to be low risk of bias [29–34, 36] and the risk of bias of one [35] was unclear (Table 2). …”

“…Two studies comparing supplementation with a prebiotic vs control for 12 weeks [34] and the Ma-Pi diet vs a control diet for 21 days [32] provided sufficient data for meta-analyses to be conducted. Changes in the relative abundance of bacteria in the genera Bifidobacterium (SMD 1.29% [95% CI −4.45, 7.03], I 2  = 33%), Roseburia (SMD −0.85% [95% CI −2.91, 1.21], I 2  = 79%) and Lactobacillus (SMD 0.04% [95% CI −0.01, 0.09], I 2  = 0%) (ESM Fig.…”

“…Four studies reported no significant differences in the inflammatory markers TNF-α, IL-6, IL-1RA or CRP between groups [29, 31, 33, 34]. Kim et al [36] reported significant reductions in faecal lipocalin 2; however, these analyses included participants without type 2 diabetes mellitus, making it difficult to extrapolate results for the subgroup of participants with type 2 diabetes.…”

“…Seven studies reported BMI at baseline [29–34, 36] and six of these studies reported BMI postintervention [29, 30, 32–34, 36]. Five studies reported no significant changes in anthropometrics, including weight, BMI and hip and waist circumferences [29, 30, 32–34].…”

Microbiome restoration diet improves digestion, cognition and physical and emotional wellbeing

“…An increasing number of studies are employing microbial analysis in order to assess the impact of various interventions on gut bacteria and also to explore the impact of gut bacteria on aspects of physiology, including metabolism. [50–52]. By using massive parallel (Next-Generation) high-throughput gene sequencing (as used by ‘Map My Gut’ [53]) we may be able to identify species-specific microbial alteration resulting from the dietary intervention.…”