Dietary Fiber from Oat and Rye Brans Ameliorate Western Diet–Induced Body Weight Gain and Hepatic Inflammation by the Modulation of Short‐Chain Fatty Acids, Bile Acids, and Tryptophan Metabolism

Abstract

Scope: Dietary fiber (DF) induces changes in gut microbiota function and thus modulates the gut environment. How this modulation is associated with metabolic pathways related to the gut is largely unclear. This study aims to investigate differences in metabolites produced by the gut microbiota and their interactions with host metabolism in response to supplementation with two bran fibers. Methods and Results: Male C57BL/6N mice are fed a western diet (WD) for 17 weeks. Two groups of mice received a diet enriched with 10% w/w of either oat or rye bran, with each bran containing 50% DF. Microbial metabolites are assessed by measuring cecal short-chain fatty acids (SCFAs), ileal and fecal bile acids (BAs), and the expression of genes related to tryptophan (TRP) metabolism. Both brans lowered body weight gain and ameliorated WD-induced impaired glucose responses, hepatic inflammation, liver enzymes, and gut integrity markers associated with SCFA production, altered BA metabolism, and TRP diversion from the serotonin synthesis pathway to microbial indole production. Conclusions: Both brans develop a favorable environment in the gut by altering the composition of microbes and modulating produced metabolites. Changes induced in the gut environment by a fiber-enriched diet may explain the amelioration of metabolic disturbances related to WD.

Lactobacillus rhamnosus GG and Oat Beta‐Glucan Regulated Fatty Acid Profiles along the Gut‐Liver‐Brain Axis of Mice Fed with High Fat Diet and Demonstrated Antioxidant and Anti‐Inflammatory Potentials

“…were generally unaffected, where only Clostridium leptum was significantly reduced. [21] The diminished production partially resulted in the reduced SCFA contents in the liver. The reduction of acetate in the liver could also be attributed to hepatosteatosis, since HFD is known to activate lipogenic genes in the liver, and hence to deploy acetate for de novo lipogenesis (DNL).…”

“…[24] This was also evidenced by the fecal bacterial profile showing elevated Lactobacilli but not Bacteroides and Bifidobacterium in the OAT group. [21] It additionally explains the lack of synergistic effects of LGG and OAT in the cecum content, since oat beta-glucan could have promoted the growth of LGG, which outcompete the acetate-producing bacteria for the prebiotic resources. Nevertheless, LGG and OAT synergistically increased acetate and propionate in the liver, suggesting that they regulated metabolic homeostasis of SCFA although their rates of production in the cecum were not restored.…”

Effects and Mechanisms of Probiotics, Prebiotics, Synbiotics, and Postbiotics on Metabolic Diseases Targeting Gut Microbiota: A Narrative Review

“…It has been reported that the administration of isomaltodextrin was positively related to the concentrations of acetic and butyric acids in mice with glucometabolic disorder [ 38 ]. Moreover, an in vivo study revealed that the intervention of dietary fiber from oat and rye brans improved body weight, glucose metabolism, hepatic inflammation, and SCFAs production in mice, accompanied with regulating bile acids and tryptophan-serotonin metabolism [ 77 ]. Furthermore, the amylosucrase-modified chestnut starch could ameliorate obesity in mice by upregulating the SCFAs-GPR43-mediated signaling pathway [ 23 ].…”

High cellulose dietary intake relieves asthma inflammation through the intestinal microbiome in a mouse model

“…A principal mechanism that the intestinal microbiome affects remote organs is through the metabolism of SCFA’s [ 25 , 26 ]. Soluble dietary fiber can produce large quantities of SCFA’s which then participate in the progression of inflammation and allergic diseases.…”