Fenugreek galactomannan and citrus pectin improve several parameters associated with glucose metabolism and modulate gut microbiota in mice.

OBJECTIVE: Galactomannans derived from fenugreek confer known health benefits; however, there is little information regarding health benefits of citrus pectin (CP) and its association with gut microbiome metabolites. The aim of this study was to examine links between galactomannan and CP consumption, microbiota development, and glucose metabolism.

DESIGN: Male C57 BL/6 J mice ages 7 to 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.

RESULTS: 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 after fiber consumption. Enhanced adenosine monophosphate-activated protein kinase (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 β oxidation via AMPK.