Studies of pomegranates, "the fruit of the gods," are increasingly revealing why they are so beneficial. Urolithin A, derived from pomegranates, and its synthetic equivalent could help treat inflammatory bowel disease, according to a new study.

The Centers for Disease Control and Prevention (CDC) suggest that around 3 million adults in the US had a form of inflammatory bowel disease (IBD) in 2015. IBD refers to two different conditions—Crohn's disease and ulcerative colitis—that are characterized by the long-term inflammation of the gastrointestinal tract, which includes the esophagus, stomach, and intestines.

In a new study, researchers from the University of Louisville, in Kentucky, identified a natural compound that could help improve IBD treatments. The researchers also explain the mechanisms through which it most likely fights IBD symptoms. The compound, called urolithin A (UroA), is a metabolite produced as a result of the interaction of gut bacteria and certain polyphenols present in pomegranates and some other fruits—particularly berries.

Specifically, ellagic acid—which is present in pomegranates and berries, such as blackberries, raspberries, and strawberries—interacts with the INIA P815 strain of Bifidobacterium pseudocatenulatum in the gut, thereby releasing UroA. This compound also has a synthetic equivalent called UAS03, which has the same, if not a stronger, therapeutic effect in the case of IBD. The researchers report their recent findings in a study paper in the journal Nature Communications.

How this substance protects gut health

Previous research indicating that UroA has multiple health benefits made the researchers keen to look into the substance's potential in the context of IBD treatments. "Previous studies demonstrated inhibitory activities of urolithins in inflammation, proliferation, and aging in various models," the researchers write.

In this new study, they used a mouse model to study the way in which UroA and UAS03 could help with IBD. Their investigation revealed that both compound versions reduce inflammation in the gut by acting on the "bridges" between the cells that make up the tissue lining the gut. UroA and UAS03 tighten these cell junctions, thus preventing toxins from passing through and causing inflammation. "The general belief thus far in the field is that urolithins exert beneficial effects through their anti-inflammatory, anti-oxidative properties," says first study author Rajbir Singh. "We have," he explains, "for the first time discovered that their mode of function also includes repairing the gut barrier dysfunction and maintaining barrier integrity."

Nutrient and gut bacteria interaction is key

Still, though the researchers encourage the consumption of pomegranates and other fruit that may lead to the release of UroA in the gut, they explain that this is no guarantee that IBD symptoms will not appear or that they will lessen. This is most likely because the bacteria that assist in the production of this metabolite may not be present at the same level—or sometimes may not be present at all—in some people's gut microbiota.

So, partly for this reason, the researchers suggest that synthetic UAS03 may be more reliable and effective in the treatment of certain forms of IBD, such as acute colitis. UAS03 also has a more stable form compared with UroA. According to the lead researcher Venkatakrishna Rao Jala, "Microbes in our gut have evolved to generate beneficial microbial metabolites in the vicinity of the gut barrier."

"However, this requires that we protect and harbor the appropriate gut microbiota and consume a healthy diet. This study shows that direct consumption of UroA or its analog can compensate for a lack of the specific bacteria responsible for production of UroA and continuous consumption of pomegranates and berries."

—Venkatakrishna Rao Jala

In the future, the team aims to conduct further studies confirming the mechanisms accessed by UroA and UAS03, as well as their protective role in IBD.