The role of fermentable dietary fibers in patients with inflammatory bowel disease (IBD) is not understood. Herein, we elucidated the effect of dietary fiber guar gum, commonly added to a wide range of processed foods, on colonic inflammation. The use of three different IBD models allowed us to examine the effect of guar gum on various aspects of human IBD, such as immune hyperactivity [IL-10 receptor (IL-10R) neutralization], epithelial injury [dextran sulfate sodium (DSS)], and infection [Citrobacter rodentium (CR)]-mediated inflammation.