Targeted modification of gut microbiota and related metabolites via dietary fiber.

Intake of dietary fiber has been proven to have several beneficial effects in maintaining host homeostasis and health. Here, we investigated the effects of different fibers on gut microbiota and related metabolites in rats. Healthy rats were supplemented with guar gum, carrageenan, glucomannan, ß-glucan, arabinoxylan, apple pectin, xylan, arabinogalactan, and xanthan gum, and these dietary fibers exhibited commonality and specificity on gut microbiota and related metabolites. The abundance of Phascolarctobacterium, Prevotella, Treponema, Butyricimonas, Bacteroides, and Lactobacillus was selectively increased by different dietary fibers, whereas the abundance of Clostridium perfringens and Bacteroides fragilis were decreased by all of these fibers. Indole-3-lactic acid was significantly increased by ß-glucan treatment, indicating the relationship between indole-3-lactic acid and Lactobacillus. Furthermore, Some species from Bacteroides were validated to produce indole-3-lactic acid, indole-3-acetic acid, and kynurenine (such as B. fragilis, B. ovatus, B. thetaiotaomicron, and B. xylanisolvens). These results provide important information on dietary guidelines based on the modification of gut microecology.

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.