Novel mechanism of dietary fiber passing through the intestine

Abstract

Anti-inflammatory and anti-allergic activities of dietary fiber (lentinan and fucoidan) are reviewed. We reported that lentinan, β-1,3; 1,6-glucan derived from Lentinula edodes, suppresses intestinal inflammation and ameliorates symptoms of colitis. Furthermore, as a mechanism, our study revealed that lentinan suppresses intestinal inflammation by Dectin-1-mediated regulation of tumor necrosis factor receptor 1 transfer to the surface of the intestinal epithelial cells. We revealed that fucoidan derived from Saccharina japonica inhibits mast cell degranulation through the upregulation of galectin-9 content in the blood. We found that residual amounts of IgE on RBL-2H3 cells were decreased by the addition of galectin-9. Galectin-9 was demonstrated to be capable of removing IgE even if IgE was already bound to mast cells and to suppress the mast cell degranulation induced by antigen. This study shows that lentinan and fucoidan might become effective therapeutic agents for patients who have already developed intestinal bowel diseases and type I allergic diseases, respectively.