The composition of the gut flora can have quite wide-ranging effects on the human body.4 Differences in gut flora can lead to differences in lactic acid metabolism, and the production of butyrate and gamma-aminobutyric acid (GABA), which may help to explain some of the pathology of mood disorders, including bipolar disorder.4
References:
1. McGuinness AJ, Loughman A, Foster JA, Jacka F. Mood disorders: the gut bacteriome and beyond. Biol Psychiatry 2024; 95 (4): 319–328.
2. Dickerson F, Severance E, Yolken R. The microbiome, immunity, and schizophrenia and bipolar disorder. Brain Behav Immun 2017; 62: 46–52.
3. Nguyen TT, Kosciolek T, Eyler LT, et al. Overview and systematic review of studies of microbiome in schizophrenia and bipolar disorder. J Psychiatr Res 2018; 99: 50–61.
4. McGuinness AJ, Davis JA, Dawson SL, et al. A systematic review of gut microbiota composition in observational studies of major depressive disorder, bipolar disorder and schizophrenia. Mol Psychiatry 2022; 27 (4): 1920–1935.