Supplementation of dietary fiber has been proved to be an effective strategy to prevent and relieve inflammatory bowel disease (IBD) through gut microbiota modulation. However, more attention has been paid to the efficacy of soluble dietary fiber than that of insoluble dietary fiber (IDF). In the present study, we investigated whether IDF from barley leaf (BLIDF) can inhibit gut inflammation via modulating the intestinal microbiota in DSS-induced colitis mice. The mice were fed 1.52% BLIDF-supplemented diet for 28 days. Results demonstrated that feeding BLIDF markedly mitigated DSS-induced acute colitis symptoms and down-regulated IL-6, TNF-α, and IL-1β levels in the colon and serum of colitis mice. BLIDF supplementation effectively reduced the abundance of Akkermansia and increased the abundance of Parasutterella, Erysipelatoclostridium, and Alistipes. Importantly, the anti-colitis effects of BLIDF were abolished when the intestinal microbiota was depleted by antibiotics. Furthermore, the targeted microbiota-derived metabolites analysis suggested that BLIDF feeding can reverse the DSS-induced decline of short-chain fatty acids and secondary bile acids in mice feces. Finally, BLIDF supplementation elevated the expression of occludin and mucin2, and decreased the expression of claudin-1 in colons of DSS-treated mice. Overall, our observations suggest that BLIDF exerts anti-inflammatory effects via modulating the intestinal microbiota composition and increasing the production of microbiota-derived metabolites.

Gut microbiota imbalances lead to the pathogenesis of non-alcoholic fatty liver disease (NAFLD), which is primarily accompanied by hepatic steatosis. Hydroxyphenyl propionic acids (HPP) have shown great potential in inhibiting lipid accumulation but their protective effects concerning NAFLD and intestinal microbiota have remained unclear. In this paper, we investigated the efficacies of 3-HPP and 4-HPP on hepatic steatosis and gut flora in mice fed a high-fat diet (HFD). We found that 3-HPP and 4-HPP administration decreased body weight and liver index, ameliorated dyslipidemia, and alleviated hepatic steatosis. Furthermore, 3-HPP and 4-HPP enhanced the multiformity of gut microbiota; improved the relative abundance of GCA-900066575, unidentified_Lachnospiraceae, and Lachnospiraceae_UCG-006 at genus level; increased concentration of acetic acid, propionic acid and butanoic acid in faeces; and reduced systemic endotoxin levels in NAFLD mice. Moreover, 4-HPP upregulated the relative abundance of genera Rikenella and downregulated the relative abundance of Faecalibaculum. Furthermore, 3-HPP and 4-HPP regulated lipid metabolism and ameliorated gut dysbiosis in NAFLD mice and 4-HPP was more effective than 3-HPP.

Inflammatory bowel disease (IBD) has become a global public health challenge. Our previous study showed that barley leaf (BL) significantly reduces Citrobacter-rodentium (CR)-induced colitis, but its mechanism remains elusive. Thus, in this study, we used non-targeted metabolomics techniques to search for potentially effective metabolites. Our results demonstrated that dietary supplementation with BL significantly enriched arginine and that arginine intervention significantly ameliorated CR-induced colitis symptoms such as reduced body weight, shortened colon, wrinkled cecum, and swollen colon wall in mice; in addition, arginine intervention dramatically ameliorated CR-induced histopathological damage to the colon. The gut microbial diversity analysis showed that arginine intervention significantly decreased the relative abundance of CR and significantly increased the relative abundance of Akkermansia, Blautia, Enterorhabdus, and Lachnospiraceae, which modified the CR-induced intestinal flora disorder. Notably, arginine showed a dose-dependent effect on the improvement of colitis caused by CR.

The incidence and prevalence of inflammatory bowel disease (IBD) have been increasing globally and progressively in recent decades. Barley leaf (BL) is a nutritional supplement that is shown to have health-promoting effects on intestinal homeostasis. Our previous study demonstrated that BL could significantly attenuate Citrobacter rodentium (CR)-induced colitis, but whether it exerts a prophylactic or therapeutic effect remains elusive. In this study, we supplemented BL before or during CR infestation to investigate which way BL acts. The results showed that BL supplementation prior to infection significantly reduced the disease activity index (DAI) score, weight loss, colon shortening, colonic wall swelling, and transmissible murine colonic hyperplasia. It significantly reduced the amount of CR in the feces and also markedly inhibited the extraintestinal transmission of CR. Meanwhile, it significantly reduced the levels and expression of tumor necrosis factor-alpha (TNF-α), interferon-gamma (IFNγ), and interleukin-1β (IL1β). In addition, pretreatment with BL improved CR-induced gut microbiota dysbiosis by reducing the content of Proteobacteria, while increasing the content of Lactobacillus. In contrast, the effect of BL supplementation during infestation on the improvement of CR-induced colitis was not as good as that of pretreatment with BL. In conclusion, BL protects against CR-caused colitis in a preventive manner.

High hydrostatic pressure (HHP) is a non-thermal pasteurization technology for the enhancement of food products’ safety and quality. The components of tomato juice can be affected by HHP processing. Little is known about the effects of HHP-processed tomato juice on the gut microbiome and metabolism. Here, we performed high-throughput sequencing and metabolomics profiling to determine the critical differences in gut microbiota structure and metabolic profiles in mice administered with HHP-processed tomato juice. Tomato juice administration significantly increased the gut bacterial alpha diversity and the relative abundance of Bacteroides. The mice administered with HHP-processed tomato juice were characterized by the enrichment of Bacteroidetes, Alistieps, and Faecalibaculum compared with those administered with HTST-processed tomato juice. Moreover, HHP-processed tomato juice promoted SCFA levels, which were positively correlated with the enriched Alistieps. Our results show that HHP-processed tomato juice may drive healthy gut microbes and metabolites.