Galactomannan More than Pectin Exacerbates Liver Injury in Mice Fed with High-Fat, High-Cholesterol Diet
. Molecular Nutrition & Food Research 2018
, 1800331. Publisher's VersionAbstract
Scope Galactomannan and citrus pectin are considered ?super fibers? known for altering gut microbiota composition and improving glucose and lipid metabolism. The study aims to investigate the fiber's effect on a nonalcoholic steatohepatitis (NASH) model. Methods and results Two feeding experiments are carried out using groups of 7?8 week-old male C57BL/6J mice. The diets used are based on a high cholesterol/cholate diet (HCD), such as a nutritional NASH model. Mice are fed a diet with or without 15% fiber-citrus pectin (HCD-CP) or galactomannan (HCD-G) together with the HCD (first experiment), which commenced 3 weeks prior to the HCD (second experiment). Liver damage is evaluated by histological and biochemical parameters. Galactomannan leads to lesser weight gain and improved glucose tolerance, but increased liver damage. This is shown by elevated levels of liver enzymes compared to that with HCD alone. Fibers induce higher steatosis, as evaluated by liver histology. This intriguing result is linked to various changes in the gut microbiota, such as elevated Proteobacteria levels in the galactomannan group, which are correlated with disturbed metabolism and dysbiosis. Conclusions In a NASH mouse model, galactomannan increases liver damage but improves glucose metabolism. Changes in the microbiota composition may answer this enigmatic observation.
Fenugreek galactomannan and citrus pectin improve several parameters associated with glucose metabolism and modulate gut microbiota in mice
. Nutrition 2018
, 134 - 142.e3. Publisher's VersionAbstract
ObjectiveGalactomannans 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.