NFKB1 and colonic neoplasm: Niacin kills colon cancer stem cells at low concentrations, but promotes colon cancer stem cell proliferation at high concentrations.[174] UDCA prevents colon cancer progression by suppressing the upregulation of cyclooxygenase‐2 and inhibiting NFκB signaling.[87, 175] However, high‐dose UDCA has cancer‐promoting effects with the mechanism remaining unclear.[176] Table 2 lists a limited number of paradoxical functions of some metabolites, and this area deserves further investigation.