Bound polyphenols are important contributors to the colitis-alleviating effect of rice bran insoluble dietary fiber, which ameliorates colitis by activating the autophagy-NLRP3 axis, suppressing ER stress, repairing the intestinal barrier, and restoring the gut microbiome and metabolome.
Bound polyphenols (BPs) are important contributors to the colitis-alleviating effect of rice bran insoluble dietary fiber (RIDF).
RIDF, relative to RIDF_DF, markedly ameliorated colitis symptoms.
RIDF mitigated endoplasmic reticulum (ER) stress relative to RIDF_DF.
RIDF restored the gut microbiome and metabolites relative to RIDF_DF.
RIDF blocked the PI3K/Akt/mTOR cascade and NLRP3 inflammasome activation.
Pharmacological modulation of autophagy showed that the autophagy-NLRP3 axis mediates the protective effects of RIDF.
BPs ameliorate colitis by activating the autophagy-NLRP3 axis, which suppresses ER stress, repairs the intestinal barrier, and restores the gut microbiome and metabolome.
This study looked at why rice bran fiber helps reduce colitis (inflammation of the colon) in an experimental setting. Most earlier research on dietary fiber focused on its carbohydrate parts. This team examined polyphenols, plant compounds that are chemically attached to the fiber, by comparing rice bran insoluble fiber that contained these bound polyphenols with a version of the fiber that lacked them. The fiber with bound polyphenols did better at easing colitis symptoms, reducing stress in the cell's protein-making machinery (ER stress), and restoring a healthier gut microbiome and its metabolites. It also dampened the PI3K/Akt/mTOR signaling pathway and the NLRP3 inflammasome, an inflammation-triggering protein complex. When the researchers blocked autophagy (the cell's recycling process) with 3-MA, the benefits disappeared. When they promoted autophagy with rapamycin, the benefits returned. This suggests that autophagy and the NLRP3 inflammasome are central to how the polyphenols work. This research suggests that bound polyphenols attached to dietary fiber may contribute meaningfully to fiber's anti-inflammatory effects in the gut, beyond the fiber's carbohydrate components. The findings come from experimental models, and the abstract does not give detailed numbers, so they do not by themselves show effects in people.
Liu L, Zheng B, Ye H, Xie J, Chen Y, Zhao X, et al.. (2026). Rice Bran Insoluble Dietary Fiber and Its Bound Polyphenols Alleviate Colitis by Regulating the Autophagy-NLRP3 Inflammasome Axis.. Journal of agricultural and food chemistry. https://doi.org/10.1021/acs.jafc.6c06416