Researchers at KU Leuven in Belgium analyzed gut bacteria from 1,054 people in the Flemish Gut Flora Project, then checked their findings against two independent groups totaling 1,070 more people, to see which microbes tracked with depression and quality of life.
Two bacterial genera, Coprococcus and Dialister, were consistently depleted in people with depression, even after accounting for antidepressant use. Separately, Faecalibacterium and Coprococcus, both butyrate-producing bacteria, were associated with higher quality of life scores across the whole population studied.
The team built a catalogue of which gut bacteria can make neuroactive compounds, finding that bacterial capacity to produce a dopamine-related metabolite correlated with better mental quality of life, and a bacterial pathway for GABA correlated with depression. This was an observational, cross-sectional study, so it shows an association between specific bacteria and mood, not proof the bacteria cause depression or that restoring them would treat it.
Read the original study
Valles-Colomer et al., Nature Microbiology, 2019 · doi.org/10.1038/s41564-018-0337-x
Two depleted microbes tracked with low mood.
Source
- Valles-Colomer, M., Falony, G., Darzi, Y., Tigchelaar, E. F., Wang, J., Tito, R. Y., Schiweck, C., Kurilshikov, A., Joossens, M., Wijmenga, C., Claes, S., Van Oudenhove, L., Zhernakova, A., Vieira-Silva, S., & Raes, J. (2019). The neuroactive potential of the human gut microbiota in quality of life and depression. Nature Microbiology, 4(4), 623–632. https://doi.org/10.1038/s41564-018-0337-x