Our guts are full of microbes like bacteria, fungi, and viruses, and this gut microbiome has to stay properly imbalanced, or it can have a bad effect on our health. Scientists assessed the gut microbiomes of over 10,000 people over a period of six years, and determined that when intestinal microbes are shifted towards 'unhealthy' groups of microorganisms, a serious infection is more likely. This infections were fatal in a few cases. The findings have been reported in The Lancet Microbe.
Of the 10,000 people that were assessed in this work, 602 developed a serious infection such as pneumonia that required hospitalization at some point during the study period. Unfortunately, some of them died from those infections. The people who had gotten infections were found to have fewer gut microbes that generate a fatty acid called butyrate. Short-chain fatty acids (SCFAs) derived from gut microbes have been shown to have a beneficial effect on health in previous studies. People with bad infections also tended to have fewer SCFA-producing bacteria.
However, the study authors wanted to know more about whether infections and subsequent treatment reduce the number of healthy gut microbes, or if people who have serious infections have always carried fewer bacteria that made butyrate, noted graduate student and co-study author Bob Kullberg.
People who carried ten percent more butyrate-producing microbes had a 15 to 25 percent reduction in their risk of serious infections in places like the lungs and bladder, noted Kullberg. The findings seem to suggest that the gut microbiome can have a huge influence on infections outside of the gut. The researchers had also considered factors such as antibiotic use, age, and comorbidities that affect infection risk.
The study concluded that butyrate can improve people's defenses against infections, and emphasized the importance of maintaining a healthy gut microbiome. Unfortunately, scientists are still learning exactly how to define a healthy microbiome, and it can probably vary significantly from one person to another. However, the ratio of Firmicutes to Bacteroidetes bacteria is thought to be one biomarker of gut microbiome health. Healthy microbiomes are also usually diverse with a rich, wide variety of species.
Researchers are also still trying to figure out why some people carry more bacteria that produce butyrate and other SCFAs, and why other people have fewer of those microbes. Investigators are also looking for reliable ways to modify and improve the health of the human microbiome, such as by adding viable, SCFA-producing bacteria to the gut.
"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," added senior study author professor Joost Wiersinga of the University of Amsterdam,
Sources: Amsterdam University Medical Centers, The Lancet Microbe
