Head Impacts May Disrupt Gut Health Even Without Concussion

THURSDAY, May 7, 2026 (HealthDay News) — Hard hits taken by football players jar more than just their brains, a new study says.

Head impacts appear to disrupt players’ gut microbiome, the colony of bacteria and organisms in the GI tract that help regulate inflammation, digestion and many other body processes, researchers reported May 6 in the journal PLOS One.

Even impacts that didn’t cause symptoms of concussion shook up players’ gut bacteria, researchers found.

“Our results provide evidence that even head impacts that do not result in a concussion or other reported symptoms may influence the microbes present within the gut, both in the short- and longer-term,” senior researcher Ken Belanger, a professor of biology at Colgate University in Hamilton, New York, said in a news release.

“Determining what causes these changes and whether they have a positive or negative influence on recovery from head injury will require further investigation,” Belanger said.

Previous studies have shown that full-fledged concussions can impact the gut microbiome, researchers said in background notes.

For this study, researchers turned to the potential impact of head impacts that don’t result in concussion by tracking the health of NCAA Division I football players across a season.

From preseason training on, the athletes’ on-field activity was monitored using GPS units, with helmet-based sensors tracking head impact. The players also provided 226 fecal samples for microbiome analysis.

Researchers found gut microbes changed within two to three days of a substantial impact.

Specifically, certain bacteria — including the order Coriobacteriales, the family Prevotellaceae, and the genus Prevotella — tended to decrease in abundance while levels of the genus Ruminococcus increased.

In previous studies, these sorts of changes have been linked to brain injury and inflammation, researchers said.

The players’ gut microbiomes also changed significantly over the course of the season, suggesting that non-concussive head impacts had a cumulative effect on gut health. This finding held even after researchers accounted for other factors that impact the microbiome including diet, exercise, sleep and stress.

“As far as we are aware, this is the first study to examine connections between head impacts and the composition of the gut microbiome — the complex community of bacteria and other organisms within the digestive system,” Belanger said.

“Our research highlights the importance of thinking integratively about the interactions between the gut and the brain,” Belanger said. “We are only beginning to scratch the surface in our understanding of how these complex organs and organ systems communicate with and affect each other.”

However, researchers noted that the study is limited by its small sample size and lack of a control group. Future research tracking more players will be needed to better understand this potential association.

More information

Houston Methodist has more on the brain-gut connection.

SOURCES: PLOS, news release, May 6, 2026; PLOS One, May 6, 2026