•For the first time galactomannan, derived from fenugreek and pectin, derived from citrus where shown to modulate gut microbiota and effect metabolic parameters and gene expression related to glucose metabolism.
•This work highlights the effect of SCFA propionate on the increased liver beta-oxidation, via AMPK activation.
•A better understanding of the mechanism linking the gut microbiome to glucose metabolism is shown.
•The findings support integration of the fibers in the food industry as thickeners and functional foods.
Galactomannans derived from fenugreek confer known health benefits. However, there is little information regarding any health benefits of citrus pectin (CP), and its association with gut microbiome metabolites is ill defined.
To examine links between galactomannan and CP consumption, microbiota development, and glucose metabolism.
Male C57BL/6J mice aged 7-8 wk were fed ad libitum with a normal diet or one supplemented with 15% of either galactomannan or CP. At 3 wk an oral glucose-tolerance test was performed. Animals were sacrificed at 4 wk and relevant organs were harvested.
Fiber enrichment led to reductions in weight gain, fasting glucose levels, and total serum cholesterol (p < 0.05). Compared with mice fed the normal diet, microbiota populations were altered in both fiber groups and were found to be richer in Bacteroidetes rather than Firmicutes (p < 0.05). The modification was significantly greater in galactomannan-fed than in CP-fed mice (p < 0.0001). Also, enhanced levels of the short-chain fatty acid (SCFA) propionate were found in the cecal contents of CP-fed animals (p < 0.05). Protein expression levels of monocarboxylate transporter 1 – which may promote transport of SCFA – were measured in the large intestines following fiber consumption. Enhanced AMPK activation was observed in livers of galactomannan-fed mice (p < 0.05). Conclusion
Consumption of diets containing soluble fibers, as used in this study resulted in gut microbiota comprising a healthier flora, and led to positive effects on weight, glycemic control, and liver beta oxidation via AMPK.
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