Can probiotics reduce bipolar symptoms? A systematic review

Background: There is growing evidence suggesting a connection between gut dysbiosis and the development of psychiatric disorders. A number of studies have shown that probiotics contribute to symptom reduction in major depressive disorder, but very few such studies have been conducted on bipolar disorder. The present study is a systematic review of such studies. Methods: Systematic review following PRISMA guidelines of studies published in the past ten years which involve the use of probiotics in patients with bipolar disorder. Results: Of 4717 articles screened, 5 were included in this review [n = 193]. Collectively, the studies measured the effects of probiotics on the symptoms of bipolar disorder as well as rehospitalization rates. Conclusion: Despite the limited number of studies done on this topic, there is evidence that probiotics improve symptoms of bipolar disorder, particularly manic symptoms, with no significant negative effects.