Molecular Properties of Guar Gum and Pectin Modify Cecal Bile Acids, Microbiota, and Plasma Lipopolysaccharide-Binding Protein in Rats

Abstract

Bile acids (BAs) act as signaling molecules in various physiological processes, and are related to colonic microbiota composition as well as to different types of dietary fat and fiber. This study investigated whether guar gum and pectin—two fibers with distinct functional characteristics—affect BA profiles, microbiota composition, and gut metabolites in rats. Low- (LM) or high-methoxylated (HM) pectin, and low-, medium-, or high-molecular-weight (MW) guar gum were administered to rats that were fed either low- or high-fat diets. Cecal BAs, short-chain fatty acids (SCFA) and microbiota composition, and plasma lipopolysaccharide-binding protein (LBP) levels were analyzed, by using novel methodologies based on gas chromatography (BAs and SCFAs) and 16S rRNA gene sequencing on the Illumina MiSeq platform. Strong correlations were observed between cecal BA and SCFA levels, microbiota composition, and portal plasma LBP levels in rats on a high-fat diet. Notably, guar gum consumption with medium-MW increased the cecal amounts of cholic-, chenodeoxycholic-, and ursodeoxycholic acids as well as α-, β-, and ω-muricholic acids to a greater extent than other types of guar gum or the fiber-free control diet. In contrast, the amounts of cecal deoxycholic- and hyodeoxycholic acid were reduced with all types of guar gum independent of chain length. Differences in BA composition between pectin groups were less obvious, but cecal levels of α- and ω-muricholic acids were higher in rats fed LM as compared to HM pectin or the control diet. The inflammatory marker LBP was downregulated in rats fed medium-MW guar gum and HM pectin; these two fibers decreased the cecal abundance of Oscillospira and an unclassified genus in Ruminococcaceae, and increased that of an unclassified family in RF32. These results indicate that the molecular properties of guar gum and pectin are important for their ability to modulate cecal BA formation, gut microbiota composition, and high-fat diet induced inflammation.

Dietary or supplemental fermentable fiber intake reduces the presence of Clostridium XI in mouse intestinal microbiota: The importance of higher fecal bacterial load and density

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Cactus (Opuntia humifusa) water extract ameliorates loperamide-induced constipation in rats

“…A recent study has reported that pectin reduces cholesterol absorption [40]. According to the report by Ghaffarzadegan et al [41], cholesterol and triglyceride levels were affected by pectin, which reduced triglycerides and plasma and liver cholesterol. However, the reduction ratios of triglycerides and cholesterol were significantly influenced by the degree of pectin esterification.…”

Green forage and fattening duration differentially modulate cecal microbiome of Wanxi white geese

“…Fiber inclusion might inhibit nutrient utilization, thus decreasing Prevotella in the ceca of geese. As described by Ghaffarzadegan et al [ 30 ], the addition of fibers from guar gum and pectincould decrease the cecal abundance of Oscillospira and an unclassified genus in the Ruminococcaceae family. Green forage inclusion could increase Oscillospira abundance, which might indicate that fiber type could modulate cecal microbiota composition.…”