Bound Phenolics Enhance the Antidepressant-Like Effect of Triticale Bran Insoluble Dietary Fiber in Obese Mice: Evidence for the Involvement of Immune Regulation and Microbiota Modulation

The high comorbidity of obesity and depression causes serious public health events when systemic inflammation induced by disturbed immunity and gut microbiota is supposed to be involved. Previously, the promoting effect of triticale bran insoluble dietary fiber (TIDF) on anti-inflammatory bacteria besides inhibiting proinflammatory bacteria was uncovered with bound phenolics (BPs) in it of great importance, while the potential effects of TIDF on obesity-concomitant depression have not been reported yet. This study found that TIDF treatment could relieve depression-like behavior, systemic inflammation, and Th17/Treg imbalance in obese mice. The regulation of microbiota-derived SCFAs was closely involved. Besides down-regulating harmful bacteria while boosting Alistipes and Candidatus_Saccharimonas by both TIDF and its BPs-removed counterpart (T-D), BPs enhanced the microbiota-modulating effects of TIDF on specific SCFAs-producing genera, including Lachnospiraceae_NK4A136_group and Eubacterium_xylanophilum_group . Our study was deemed to promote the application of food nutritional factors in relieving obesity-concomitant emotional disturbance.