New research highlights the crucial role that gut bacteria play in determining a person's risk of infection. A study involving over 600 hospitalized patients found that those with infections had fewer gut bacteria capable of producing butyrate, a beneficial fatty acid.

Butyrate is produced by certain bacteria as they digest dietary fiber. Previous studies have shown that people battling serious infections typically have lower levels of these butyrate-producing bacteria. While butyrate has been known to boost the immune system in mice, its effects in humans were unclear until now.

"We didn't know whether the less healthy gut flora is due to the acute infection and its treatment or whether they have always had less of the butyrate-producing bacteria in their microbiome," explained study co-author Bob Kullberg, a doctoral student at Amsterdam University Medical Center. "The study now answers this chicken-and-egg question."

Researchers examined stool samples from more than 10,000 people, focusing on 16 types of bacteria that produce butyrate. Among the study participants, 602 were hospitalized during the research period.

"We saw that in people who have 10% more of those bacteria in their gut, the chance of getting an infection decreases by as much as 15% to 25%," Kullberg stated in a news release from the medical center. This suggests that the microbiome influences infections beyond the gut, such as bladder or lung infections.

The researchers accounted for factors like age, antibiotic use, and underlying diseases, all of which can impact gut bacteria balance. The findings, published on June 20 in The Lancet Microbe, underscore the importance of a healthy microbiome and open new avenues for predicting infection risk and potential treatments.

"Follow-up research is needed to find out how we can increase the amount of butyrate with diet or probiotics, in order to prevent serious infections," said Dr. Joost Wiersinga, chair of the Division of Infectious Diseases at the medical center.

This study emphasises the vital connection between gut health and overall infection risk, highlighting the potential for dietary and probiotic interventions to bolster the immune system.