To determine the biological role of bacterial enzymes in inhibiting CRC progression, LeBlanc et al. detected the existence of antioxidant enzymes, such as catalase (CAT) or superoxide dismutase (SOD) in the gut and their function in eliminating 2,4,6-Trinitrobenzenesulfonic acid (TNBS)-induced Crohn’s disease in mice, which was believed to be the major trigger of CRC (285). Here, CAT is linked to Crohn disease.