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Introduction: Dietary fiber and flavonoids are promising drugs reported in the treatment of inflammatory bowel disease (IBD). However, it is unclear the interaction between dietary fiber and flavonoids in gut health. Objective: The therapeutic effect of celery, kale, and red chicory powders on colitis mice using non-group feeding cages was investigated. Further, the efficacy of whole celery, celery soluble dietary fiber (CSDF), celery insoluble dietary fiber (CIDF), celery flavonoids (CF), CSDF + CF and CIDF + CF in IBD mice model was assessed to dissect protective effect to attribute to which component(s) in such complex matrix. Methods: 3% Dextran sulfate sodium salt (DSS) was used to induce mice colitis model. Multiple molecular biological methods were employed to evaluate the severity of mice colitis and the gut microbial composition of mice. Results: Administration of kale and red chicory significantly restored body weight, DAI score, and colon length in colonic mice, and celery showed the weakest effects. Administration of either CSDF or CF markedly improved the histological damage, increased colonic mucus expression, and reduced colonic MPO/iNOS activities, and IL-6/IL-1β levels. However, CSDF + CF showed weaker improvement than CF or SDF in most physical and biochemical signs. Furthermore, CSDF and CF decreased intestinal g_Escherichia-Shihella and g_Clostridium_sensu_stricto_1 induced by DSS administration. Interestingly, celery flavonoid promoted g_Akkermansia proliferation both in vivo and in vitro, and which can be inhibited by CSDF. Conclusions: This study revealed for the first time that CSDF can suppress the protective effect of CF on intestinal health by inhibiting g_Akkermansia, and clarified that the decreased efficacy of celery whole food on colitis was mediated by an antagonism between CSDF and CF. Moreover, this study presents for the first time that interaction between soluble dietary fiber and flavonoids in vivo can ameliorate the efficacy of dietary fiber or flavonoids when administered alone suggestive for an antagonistic effect.

Abstract Kale has been reported to have potential alleviating effects on colitis. However, the functional activities of kale dietary fibers and kale flavonoids (KF), as well as the effects of their combined use, were currently unknown. In this study, the efficacy of whole kale, kale soluble dietary fiber (KSDF), kale insoluble dietary fiber (KIDF), KF, mixture of KSDF and KF, and mixture of KIDF and KF on dextran sulfate sodium‐induced colitis mice was assessed to dissect which component(s) play the key role in alleviating colitis. The study demonstrated that administration of KSDF, KIDF, or KF resulted in various degrees of beneficial effects, including reduction of weight loss, colonic shortening, disease activity index score, and mRNA levels of inflammatory factors (TNF‐α, IL‐6, IL‐1β, and IL‐33), increase of mucin expression and suppression of intestinal g_Sutterella, g_Parabacteroides, f_Enterobacteriaceae relative abundance. However, 20% mouse mortality was found in group of KSDF combined with KF. Further analysis found that the combination antagonized the alleviating effects of both agents alone on colitis in mice. It is the first to report that there is antagonism between KSDF and KF in colitis, and the regulation of intestinal flora may be the mechanism. In addition, this study also showed that KSDF, KIDF, and KF alone had excellent effects to alleviate colitis. This study provides a new perspective and evidence to explore the effect of interaction among different food nutrients on intestinal inflammation.

Introduction: Colonic urea-nitrogen metabolites have been implicated in the pathogenesis of certain diseases which can be affected by environmental factors. Objectives: We aimed to explore the influence of ambient humidity on colonic urea-nitrogen metabolism. Methods: Blood biochemical indexes, metabolites of intestinal tract, and gut microbiota composition of mice (n = 10/group) exposed to high relative humidity (RH, 90 ± 2%) were analyzed during the 14-day exposure. Results: After 12-h exposure, plasma blood urea nitrogen (BUN) level increased along with a decrease in the activity of erythrocyte Na+/K+ -ATPase. Moreover, abnormal erythrocyte morphologies appeared after 3 days of exposure. The colonic BUN and ammonia levels increased significantly after the 12-h and 24-h exposure, respectively. The colonic level of amino acids, partly synthesized by gut microbiota using ammonia as the nitrogen source, was significantly higher on the 7th day. Furthermore, the level of fecal short-chain fatty acids was significantly higher after 3-day exposure and the level of branched-chain fatty acids increased on the 14th day. Overall, gut microbiota composition was continuously altered during exposure, facilitating the preferential proliferation of urea-nitrogen metabolism bacteria. Conclusion: Our findings suggest that short-term high RH exposure influences colonic urea-nitrogen metabolism by increasing the influx of colonic urea and altering gut microbiota, which might further impact the host health outcomes.

Coix lachryma-jobi L. seed is an important food item in Asia with culinary and medicinal values. The effects of non-fermented coix seed (NFC), fermented coix seed with Lactobacillus plantarum NCU137 (FC) and polysaccharides from NFC, FC (FCP) on mice circulating nitrogen and immune disorder induced by high relative humidity (RH, 90 ± 2%) exposure were compared. All the treatments reduced circulating nitrogen (BUN and ammonia) might via increasing excretion of fecal nitrogen induced by altering gut microbiota. In comparison, FC and FCP restored erythrocyte morphology by promoting erythrocyte Na+/K+ ATPase activity more effectively, and immune function was modulated by reducing plasma IgM and IFN-γ levels, up-regulating IL-4 and IL-6 levels. Herein, these results indicated that FCP, as the main active ingredient in FC, modulated circulating nitrogen through altering gut microbiota, and restored immune homeostasis by regulating Th1/Th2 cytokines in mice receiving high RH exposure.

Both tea polysaccharides (TPS) and tea polyphenols (TPP) are promising in the treatment of inflammatory bowel disease (IBD). However, the effects of their combination against IBD are still unknown. In the present study, the therapeutic effects of TPS, TPP and TPS + TPP on dextran sodium sulfate-induced colitis in mice were investigated. Our results showed that administration of TPS + TPP achieved the best effects, followed by TPP and TPS, which were evidenced by the restoration of various physical signs (body weight, colon length and disease activity index) and the promoted intestinal barrier function (colon damage, mucin secretion and tight junction proteins expression). Furthermore, TPP and TPS decreased the relative abundance of Proteobacteria and Enterobacteriaceae, while TPP + TPS increased that of Lactobacillaceae and Lactobacillus. In conclusion, TPS together with TPP had greater effects on alleviating colitis and promoting intestinal barrier function. This result is interesting when developing functional foods against colitis.