Preventive and/or remedy for inflammatory bowel diseases

A method for treating an inflammatory bowel disease (IBD) comprising administering an effective amount of a fermented milk whey obtained from fermenting milk whey with Propionibacterium freudenreichii ET-3 to a subject in need thereof, wherein the fermented milk whey comprises 1,4-dihydroxy-2-naphtholic acid (DHNA), wherein the Propionibacterium freudenreichii ET-3 may be optionally removed from the fermented milk whey after fermentation, and wherein the DHNA content in said fermented milk whey is from 0.001 to 0.01 w/w % of the solid content of the fermented milk whey.