How fruits and nuts could support gut health

A substance made by gut bacteria from foods such as pomegranates and walnuts helped shield the intestinal lining in laboratory experiments led by the University of Louisville. The results point researchers toward a new avenue to study in inflammatory bowel disease, which can harm the barrier separating the gut from the rest of the body.

That barrier serves two purposes at once. It allows nutrients to enter the body while helping keep microbes and other potentially harmful material inside the intestine.

In Crohn’s disease and ulcerative colitis, the two main forms of inflammatory bowel disease, inflammation can weaken the lining. Researchers are interested in whether signals that support or restore the barrier could work alongside existing treatments.

The Louisville researchers focused on urolithin A, a compound certain gut bacteria produce from substances found in pomegranates, walnuts and some berries. Their study in Nature Communications followed what happened when the compound reached cells lining the intestine.

The process began with a protein called AHR, which detects substances from food, microbes and the environment. When urolithin A activated this sensor in lining cells, it triggered a chain of signals involving another group of proteins known as NLRP6.

NLRP6 is part of an immune alarm system. In the experiments, switching it on caused lining cells to release an immune messenger that prompted nearby immune cells to send a second signal.

Those signals together increased the production of mucus and a protein that helps control bacteria near the intestinal surface. Mucus coats the lining, while the protein is part of the body’s effort to limit contact between microbes and sensitive tissue. Both defenses help keep bacteria away from the cells lining the intestine.

The team examined the process in mice and in lab-grown intestinal tissue models. It also exposed small pieces of intestinal tissue from people with inflammatory bowel disease to urolithin A and found that the tissue produced the two immune messengers involved in the response.

That result suggests human tissue can react under experimental conditions. It remains unclear whether the same response would be strong enough to repair the lining or ease symptoms in someone living with the disease.

The study used the compound itself, so it did not test what happens when patients eat more fruit or nuts. People may also differ in the microbes they carry and in how much urolithin A those microbes produce from the same foods.

Further research can determine whether targeting this response is safe and helpful in patients. The discovery narrows the search to a specific set of signals that helps the gut lining defend itself.

If you are interested in this topic, please read articles about Low Vitamin D May Make Inflammatory Bowel Disease Worse, and Black Licorice Compound Could Reduce Gut Inflammation Study Finds.

For more information, please see articles about How Ultra Processed Foods Are Rapidly Rewriting the Evolution of Gut Bacteria, and New 5 Day Diet Improves Health in People with Crohns Disease.

Source: University of Louisville.