Feed your gut with caution!
The intestinal epithelium, a single layer of cells organized into crypts and villi, is an important component of host defense against microbial community and its noxious metabolites. To preserve the epithelium integrity under constant exposure of intense physiological and environmental stressors, this surface is continuously and rapidly renewed by pluripotent intestinal epithelial stem cells that reside in the base of crypts. A recent study by Kaiko et al. shows that structural design of intestinal crypts protects the colonic epithelial stem/progenitor cells from proliferation-suppressing metabolites derived from the gut microbiota. Among these metabolites, butyrate is identified as the most potent inhibitor of colonic epithelial stem/progenitor cells proliferation. By rapidly metabolizing the butyrate, the colonocytes at the crypt further institute a metabolic barrier to protect the crypt-resident stem cells that fuel its renewal and repair.