The Microbiome
Not all bacteria is bad – microbes, in fact, contribute to human physiology, taking a role in the human digestive and immune system. Gut microbiota aid in the former; they extract nutrients for humans from otherwise indigestible substrates. In addition to digestion, the NCBI highlights their role in protecting against irritable bowel disease, Clostridium difficile, and other diseases involved with the digestive system. But these microbes appear to affect more than human physical health; humans seem to have developed a dependence on these microbes, not just nutritionally, but also mentally.
Link to Depression
Two separate studies of Europeans found that the absence of certain gut microbes could be linked to depression, with an emphasis on the word “could” because there is not enough data to back up causality. The groups observed consisted a group of 1054 Belgians and another of 1064 Dutch people. The link between microbiota and mood was shown in several tests with mice, but a Belgian microbiologist called Jeroen Raes wanted to apply it to a larger group. The Belgian study observed the “normal” microbiome, but the study’s focus shifted to the abnormal. Out of the 1054 Belgians, 173 of them were either diagnosed with depression or had a poor quality of life. Comparing their microbiomes to the rest of the group, these Belgians were missing two microbes: Coprococcus and Dialister. The Dutch study also found the same two microbes missing from the participants diagnosed with depression.
More studies and treatments
Including the study of mice, there have been 3 independent studies that suggest a link between the absence of Coprococcus and Dialister and the presence of depression. Of course, it is still too early to claim anything final, but further studies can help solidify this connection. Raes suggests that this connection can lead to “novel therapies” including oral bacterial supplements and fecal transplant. Finding a link can change the way mental health patients are treated- promoting the growth of beneficial microbiota or replacing the lack of can possibly improve mental health.
Microbiology 