Gut microbiome composition is linked to whole grain-induced immunological improvements

Abstract

The involvement of the gut microbiota in metabolic disorders, and the ability of whole grains to affect both host metabolism and gut microbial ecology, suggest that some benefits of whole grains are mediated through their effects on the gut microbiome. Nutritional studies that assess the effect of whole grains on both the gut microbiome and human physiology are needed. We conducted a randomized cross-over trial with four-week treatments in which 28 healthy humans consumed a daily dose of 60 g of whole-grain barley (WGB), brown rice (BR), or an equal mixture of the two (BR þ WGB), and characterized their impact on fecal microbial ecology and blood markers of inflammation, glucose and lipid metabolism. All treatments increased microbial diversity, the Firmicutes/Bacteroidetes ratio, and the abundance of the genus Blautia in fecal samples. The inclusion of WGB enriched the genera Roseburia, Bifidobacterium and Dialister, and the species Eubacterium rectale, Roseburia faecis and Roseburia intestinalis. Whole grains, and especially the BR þ WGB treatment, reduced plasma interleukin-6 (IL-6) and peak postprandial glucose. Shifts in the abundance of Eubacterium rectale were associated with changes in the glucose and insulin postprandial response. Interestingly, subjects with greater improvements in IL-6 levels harbored significantly higher proportions of Dialister and lower abundance of Coriobacteriaceae. In conclusion, this study revealed that a short-term intake of whole grains induced compositional alterations of the gut microbiota that coincided with improvements in host physiological measures related to metabolic dysfunctions in humans.

Low-energy diets differing in fibre, red meat and coffee intake equally improve insulin sensitivity in type 2 diabetes: a randomised feasibility trial

“…The mechanisms responsible could be alterations to gut microbiota improving systemic inflammation independently of weight loss [29], altered digestion and/or absorption of protein subsequently affecting Changes at the end of the intervention period have been compared with the end of the runin period/baseline assessment using Student's t test for paired samples; not-normally distributed values were log e -transformed. *p<0.05, **p<0.01, ***p<0.001 the amino acid profile [12], or altered rates of colonic fermentation with production of short-chain FA [29]. Chronic coffee consumption has been reported to have similar effects [30].…”

Consumption of a Bifidobacterium bifidum Strain for 4 Weeks Modulates Dominant Intestinal Bacterial Taxa and Fecal Butyrate in Healthy Adults

“…The expansion of Ruminococcaceae in centenarians has been reported, with a positive correlation with high-fiber diets (39) and after intervention with resistant starch (40). Furthermore, in the study by Martínez et al, Ruminococcaceae were more dominant in normoweight than obese individuals and negatively correlated with markers of inflammation (41). A lower abundance of this taxon was associated with exaggerated Toll-like receptor 2 (TLR-2) responses and an increased risk of developing IgE-associated eczema in infants (42).…”

Dynamics and diversity of the ‘Atopobium cluster' in the human faecal microbiota, and phenotypic characterization of ‘Atopobium cluster' isolates

“…Uncultured representatives of the class Coriobacteriia have been correlated with host lipid metabolism in human (Lahti et al, 2013) and animal (Martínez et al, 2009(Martínez et al, , 2013Claus et al, 2011) studies, andHoyles (2009) suggested that Col. aerofaciens plays a role in lipid metabolism within the large intestine. As such, the resuscitatable (217/224) faecal 'Atopobium cluster' isolates were assayed for lipase activity using olive oil/rhodamine B agar as described by Hoyles (2009), with Staphylococcus aureus (positive) and Escherichia coli (negative) used as controls.…”