A high dietary intake of fruits and vegetables is associated with a reduced disease risk. The fruits and vegetables
contain fibers, vitamins, phytosterols, sulfur compounds, carotenoids, and organic acids, which all provide beneficial
effects on health, but they also contain a variety of polyphenols. Recently, polyphenols have received considerable attention
because of their various physiological effects, including anti-oxidative, anti-inflammatory and anti-carcinogenic effects.
In addition, experimental evidence demonstrates that some polyphenols participate in regulation of intestinal tight
junction (TJ) barrier. The TJ, a multiple-protein complex, regulates the paracellular permeability between the epithelial
cells and the dysfunction is implicated with the pathogenesis of intestinal and systemic diseases. Among polyphenols investigated,
quercetin, kaempferol, myricetin, morin, hesperetin, naringenin and daidzein have been reported to enhance
the basal TJ integrity in intestinal cells. In most cases, the enhancements are accompanied by increases in the expression
and/or cytoskeletal association of TJ proteins, such as occludin, claudins and zonula occludens. Genistein, epigallocatechin-
3-gallate and curcumin present protective effects on the TJ integrity against harmful substances, such as oxidative
stress and pro-inflammatory cytokines. Chrysin increases the intestinal permeability through decreased expression and cytoskeletal
association of TJ proteins. Based on these evidences, the regulation of intestinal TJ barrier by polyphenols could
be therapeutic and preventive approaches for intestinal barrier defect-associated diseases.