The effects of pectin on the gut microbiota and serum metabolites in mice fed with a high fat diet and exposed to low-dose antibiotics.

A sedentary lifestyle, unhealthy diet, and antibiotic use among other environmental factors have been associated with an increased incidence of metabolic disorders and inflammation, as well as gut dysbiosis. Pectin is an edible polysaccharide that exists widely in the cell wall of plants. Our previous study has shown that pectin with various degrees of esterification displayed different effects on preventing acute colitis and regulating the gut microbiome and serum metabolome. This study aimed to further explore the differential effects of pectin with various degrees of esterification on mice simultaneously treated with a high-fat diet and low-dose antibiotics. The results showed that low-esterified pectin L102 improved the biomarkers of metabolic disorders including blood glucose and body weight. The high-esterified pectin H121 and the low-esterified pectin L13 ameliorated inflammatory markers such as superoxide dismutase (SOD). The enrichment of probiotic bacteria such as Lactobacillus by pectin L102, reduction of conditional pathogens such as Klebsiella by pectin L13, and changes in circulating metabolites like L-tryptophan and 3-indoleacrylate by all three types of pectins were detected. These data provide evidence for a differential effect of different types of pectin on the gut microbiota and metabolic health.

Effects of boiling and steaming process on dietary fiber components and in vitro fermentation characteristics of 9 kinds of whole grains.

Whole grains (WGs) are considered as the representative sources of dietary fiber (DF). Thermal treatments can change the properties of DF, and potentially affecting the gut microbiota as well as human health. In this study, DF content and in vitro fermentation characteristics of 9 kinds of WGs (highland barley, barley, buckwheat, proso millet, quinoa, sorghum, coix seed, foxtail millet, and oats) after boiling and steaming treatments were compared. It was found that boiling and steaming treatments could both increase DF content in these grains, except for barley and foxtail millet. Processed WGs could regulate beneficial microbial genus, such as Bifidobacterium, Prevotella, Megamona and Megasphaera. Oats, quinoa, highland barley, and buckwheat after boiling treatment can produce more total short-chain fatty acids (SCFAs) than steaming treatment (p < 0.05), while barley, foxtail millet and coix seed showed opposite results. This study can provide data support for the design of WGs diets and the development of WGs products which are beneficial for gut health.

Impact of pectin with various esterification degrees on the profiles of gut microbiota and serum metabolites.

Colitis is generally affected by multiple factors, including the dysbiosis of intestinal microbiota, and may affect organs outside colon through circulation. Pectin, which is an edible polysaccharide widely present in plant cell walls, has been proved in our previous study to possess preventive potentials against acute ulcerative colitis, especially when the esterification degree is less than 50%. This study aimed to clarify the underlying correlations of gut microbiome and serum metabolites with the preventive effects of pectin with different esterification degrees (H121, L13, and L102) against colitis in mice. MiSeq sequencing data showed that symbiotic bacteria especially beneficial Lactobacillus and Bifidobacterium were enriched by pectin intake. Fiber consumers such as Prevotella and Bacteroides actively responded to L13 pectin, particularly under high dosage (L13-H). In addition, the abnormal abundance of Akkermansia associated with colitis would not appear in mice who had been provided with any of the three pectins before dextran sulfate sodium (DSS) treatment. Furthermore, pre-treatment of H121 and L13 pectins could improve the serum glycerophospholipids such as phosphatidylcholine (PC) and phosphatidylethanolamine (PE). In contrast, lysophosphatidic acid (LPA) contributing to the glycerophospholipid metabolism pathway was enriched only in the L13-H group, which has been previously proved to be associated with the epithelial barrier and intestinal homeostasis. Positive relationships between the glycerophospholipids and the dominant candidates of intestinal bacteria such as Lactobacillus indicated the joint actions of intestinal microbes and serum metabolites as well as the underlying crosstalks among gut microbiome. Therefore, the results of this research suggested that the preventive effects of low-esterified pectin on DSS-induced colitis were likely to be initiated by the enrichment of probiotics in the gut and serum glycerophospholipids. KEY POINTS: • L13 pectin remarkably improved the diversity of the gut microbiome in healthy mice. • Probiotics were enriched and abnormal Akkermansia was restored by L13 and L102 pectins. • Glycerophospholipid metabolism was significantly enriched by H121 and L13 pectins.

Preventive effects of pectin with various degrees of esterification on ulcerative colitis in mice.

This work investigated the physiochemical characteristics and preventive effects of purified pectin (H121, L13 and L102) with different esterification degrees on dextran sulfate sodium (DSS)-induced colitis in mice. Three doses of each type of pectin were administered to C57BL/6J mice for 7 days before the DSS treatment, with dextran and mesalazine as positive controls. Results showed that pathological factors including the body weight, the disease activity index (DAI), the colonic weight/length ratio and the organ index of the spleen were improved with pre-intervention of a high dose of L13 or L102. Further studies showed that administration of a low dose of L13, low dose and medium dose of L102 or dextran improved intestinal permeability and tight junction function in colitis mice. Treatments of L13 of all doses and L102 of a high dose downregulated the oxidative stress-associated factors, while L102 of a low dose and H121 ameliorated the inflammatory cytokine production in serum and the colon. The above results suggested that pectin could attenuate DSS-induced intestinal epithelial injury, inflammation and oxidative stress. Specifically, compared to high esterified pectin, low esterified pectin displayed better protective effects in acute colitis mice.