Foods such as pomegranates, walnuts and berries may help supply the starting material for a compound linked to gut barrier protection. But there is an important middle step: the right gut microbes have to help make it.
A new study published in Nature Communications found that urolithin A, a compound produced by some gut bacteria after they break down compounds in certain fruits and nuts, activated a protective response in intestinal cells. The findings may help researchers better understand how diet, gut microbes and the immune system interact in inflammatory bowel disease, but the study did not test whether eating pomegranates, walnuts or berries treats Crohn’s disease, ulcerative colitis or any other gut condition.
Inflammatory bowel disease, or IBD, includes Crohn’s disease and ulcerative colitis. These conditions involve chronic inflammation and damage to the intestinal lining. That lining acts as a barrier, helping keep harmful bacteria and other unwanted substances from moving out of the gut while still allowing nutrients to pass into the body. When the barrier is weakened, inflammation and tissue damage can worsen.
Researchers at the University of Louisville studied urolithin A, often shortened to UroA. The compound is connected to foods rich in ellagitannins and related compounds, including pomegranates, walnuts and berries. The study used several research models, including intestinal cells, lab-grown gut tissue, animal models and intestinal tissue samples from patients with IBD. It was not a clinical trial of a food, diet or supplement in people.
The researchers found that UroA activated a protein that helps intestinal cells respond to signals from food, microbes and the environment. That response appeared to turn on a repair-related pathway in the cells that line the gut.
“The findings show that not all inflammatory pathways are harmful,” said Sweta Ghosh, previously a postdoctoral researcher in Venkatakrishna Rao Jala’s laboratory and lead investigator on the study. “Under the right conditions and in the right cells, these pathways can play an essential role in maintaining gut health and supporting tissue repair.”
In the study, this response was linked to gut lining repair, mucus production and defenses that help the intestine manage microbes. The researchers also found signs of the same protective response in human intestinal tissue samples from patients with IBD.
That human tissue finding makes the work more relevant than a cell-only experiment, but it still does not show that people with IBD can improve symptoms or repair the gut lining by changing their diet. It also does not mean everyone produces the same amount of urolithin A after eating foods such as pomegranates, walnuts or berries. Production depends partly on the gut microbiome, which varies from person to person.
Jala, an associate professor in the Department of Microbiology and Immunology at the University of Louisville and the UofL Brown Cancer Center, said the study may point toward more targeted ways to support intestinal balance.
“This study helps us better understand how natural compounds produced through interactions between diet, gut microbes and the body can influence disease processes,” Jala said. “By identifying this specific protective pathway, we may be able to develop more targeted therapeutic approaches that restore intestinal balance instead of broadly suppressing immune responses.”
That future treatment angle is important but early. Current IBD care should be guided by medical professionals, and this study does not support using specific foods or urolithin A products as a substitute for prescribed treatment.
The findings add to a growing area of gut health research: food may influence health partly through compounds made by gut microbes. In this case, the story is not just about fruits and nuts. It’s about the chain reaction among food compounds, gut bacteria and the cells that help protect the intestinal lining.
That nuance matters. A food can contain helpful starting materials without acting like medicine on its own. A microbe-made compound can look promising in lab and tissue studies without being proven as a treatment. Gut health research can be exciting and still be several steps away from a practical recommendation.
The study was supported by several National Institutes of Health grants, The Jewish Heritage Fund for Excellence, the University of Louisville Department of Microbiology and Immunology and the UofL Brown Cancer Center. Venkatakrishna Rao Jala, one of the study authors, is a co-founder of Artus Therapeutics.