When it comes to depression, the part of the body that immediately comes to mind is the brain. But according to a new report, the bacteria in your gut can play a major role in your mental health.

A Long Look

The authors of this report came across this finding upon reviewing data from a long-running Finnish study. Beginning in 2002, the research team began tracking 6,000 Finns, observing their eating habits, lifestyles, prescription drug use and overall health. In addition, the genetic makeup of these individuals was thoroughly analyzed and documented. The authors kept close tabs on this group until 2018.

Upon sifting through all this data, the research team identified two types of bacteria that appeared to be connected to depression, known as Morganella and Klebsiella. The former was found to be especially prevalent among 181 study participants who were later diagnosed with depression.

A New Way Forward?

The study’s findings caught the attention of others in the field of microbiology. For example, Jeroen Raes, a microbiologist at KU Leuven, praised the report as “really exciting.” The important takeaway, contends Raes, is that the study authors were able to show how the presence of certain bacteria lead to a greater risk of depression. Jack Gilbert, a microbial ecologist at the University of California, San Diego, expressed similar sentiments, noting that the report “is really solid proof that this association could have major clinical importance.”

The journal Nature Genetics published the team’s work. According to the National Institute of Mental Health, about 21 million adults in the United States experienced a depressive episode in 2020.