Effects of Three Homogalacturonan-Type Pectins on Mice with Metabolic Syndrome

Pectin, a class of dietary fiber, has received increasing attention in recent years for its ameliorative effects on metabolic diseases. However, the structural variability of pectin leads to differential effects on these diseases. The intrinsic mechanism by which pectin, derived from different sources, differentially influences metabolic syndrome by interacting with gut microbiota and host metabolism remains elusive and warrants thorough investigation. To address this, we investigated the effects of HG-type pectins from apple, citrus, and pomelo on phenotypic expressions, inflammatory factors, oxidative stress, and serum hormone levels in mice with metabolic syndrome. In addition, we sought to identify pivotal bacterial species and metabolites by integrating genomics and metabolomics approaches. Our exploration also extended to the relationship between structural characteristics of pectins, gut microbiota, and metabolic syndrome. Our findings revealed that the three pectins diversely improved metabolic syndrome in mice, which correlated with gut microbiota and their beneficial metabolites. Notably, all three pectins were closely associated with Bacteroides and Bacteroides acidifaciens. Besides, the potential mediators of the therapeutic effects included Bacteroides, Lactococcus, and Lachnoclostriclum for apple pectin; Colidextribacter, Bacteroides, Lachnospiraceae_NK4A136_group, and Lachnoclostriclum for citrus pectin; and Lachnospiraceae_NK4A136_group, Bacteroides, and Mucispirillum for pomelo pectin. Metabolites such as arachidonic acid, kynurenic acid, lithocholic acid, deoxycholic acid, and indoleacetic acid, linked to these microbes, may serve as the mediators of pectin's benefits. Ultimately, the molecular weight, degree of esterification, and monosaccharide composition of pectins significantly influenced the outcomes. This study may contribute to a more nuanced understanding that can inform targeted nutritional strategies to modulate gut microbiota for metabolic syndrome management.