SummaryThis study was conducted to elucidate the effects of dietary polyphenols on intestinal immunoglobulin A (IgA) response and mucin levels in rats fed a high-fat diet. In experiment 1, rats were fed a high-fat diet with or without several polyphenols including curcumin, rutin, D( ϩ )-catechin, ellagic acid and quercetin at the level of 0.5%. Among the polyphenols examined, consumption of curcumin markedly elevated the level of IgA in feces and colon contents. In experiment 2, rats were fed a high-fat diet or a low-fat diet with or without 0.5% curcumin. Fecal level of IgA was higher in the high-fat diet group than in the low-fat diet group. In the rats fed the high-fat diet, dietary curcumin elevated fecal IgA, but not in those fed the low-fat diet. These results imply a novel effect of curcumin on intestinal IgA in animals fed a high-fat diet.