Gut microbe metabolite from berries and walnuts may protect intestinal lining

Researchers have found that urolithin A, a compound produced by gut bacteria from foods like pomegranates, walnuts, and berries, activates a protective pathway in the intestine. This pathway, involving the aryl hydrocarbon receptor, may help repair and maintain the gut barrier, offering a potential target for treating inflammatory bowel disease. The discovery highlights a beneficial role for a signaling mechanism previously linked to environmental toxins.

Urolithin A emerges from the digestion of common foods—pomegranates, walnuts, and berries—when gut bacteria metabolize their natural compounds. The University of Louisville team demonstrated that this metabolite selectively engages the aryl hydrocarbon receptor within intestinal epithelial cells, the cells forming the gut's protective lining. This activation triggers the NLRP6 inflammasome, a complex typically associated with harmful inflammation, yet here it orchestrates a constructive response: reinforcing the barrier, boosting mucus production, and strengthening antimicrobial defenses.

The study, published in Nature Communications, clarifies why AHR activation sometimes causes harm and other times protects. The outcome hinges on where activation occurs and its intensity. This represents the first documented example of a microbial natural product cooperating with the body's regulatory machinery during intestinal injury, potentially informing future therapeutic strategies for Crohn's disease and ulcerative colitis.