title: Probiotic supplementation can positively affect anxiety and depressive symptoms: a systematic review of randomized controlled trials.
abstract: Gastrointestinal microbiota, consisting of microbial communities in the gastrointestinal tract, play an important role in digestive, metabolic, and immune functioning. Preclinical studies on rodents have linked behavioral and neurochemical changes in the central nervous system with deficits or alterations in these bacterial communities. Moreover, probiotic supplementation in rodents has been shown to markedly change behavior, with correlated changes in central neurochemistry. While such studies have documented behavioral and mood-related supplementation effects, the significance of these effects in humans, especially in relation to anxiety and depression symptoms, are relatively unknown. Thus, the purpose of this paper was to systematically evaluate current literature on the impact of probiotic supplementation on anxiety and depression symptoms in humans. To this end, multiple databases, including Medline, PsycINFO, PubMed, Scopus, and Web of Science were searched for randomized controlled trials published between January 1990 and January 2016. Search results led to a total of 10 randomized controlled trials (4 in clinically diagnosed and 6 in non-clinical samples) that provided limited support for the use of some probiotics in reducing human anxiety and depression. Despite methodological limitations of the included trials and the complex nature of gut-brain interactions, results suggest the detection of apparent psychological benefits from probiotic supplementation. Nevertheless a better understanding of developmental, modulatory, and metagenomic influences on the GI microbiota, specifically as they relate to mood and mental health, represent strong priorities for future research in this area.
authors.affiliation: School of Kinesiology and Health Science, York University, Toronto, Ontario, Canada.
authors.forename: Meysam
authors.initials: M
authors.lastname: Pirbaglou
authors.affiliation: School of Kinesiology and Health Science, York University, Toronto, Ontario, Canada; Department of Psychology, York University, Toronto, Ontario, Canada.
authors.forename: Joel
authors.initials: J
authors.lastname: Katz
authors.affiliation: Department of Clinical Epidemiology & Biostatistics, McMaster University, Hamilton, Ontario, Canada.
authors.forename: Russell J
authors.initials: RJ
authors.lastname: de Souza
authors.affiliation: Department of Medicine, McMaster University, Hamilton, Ontario, Canada.
authors.forename: Jennifer C
authors.initials: JC
authors.lastname: Stearns
authors.affiliation: School of Kinesiology and Health Science, York University, Toronto, Ontario, Canada.
authors.forename: Mehras
authors.initials: M
authors.lastname: Motamed
authors.affiliation: School of Kinesiology and Health Science, York University, Toronto, Ontario, Canada; Department of Psychology, York University, Toronto, Ontario, Canada; University Health Network, Princess Margaret Cancer Centre, Toronto, Ontario, Canada. Electronic address: paul.ritvo@gmail.com.
authors.forename: Paul
authors.initials: P
authors.lastname: Ritvo
mesh_terms: D000339:Affect; D000818:Animals; D001007:Anxiety / Q000188:drug therapy*; D003863:Depression / Q000188:drug therapy*; D019587:Dietary Supplements; D000069196:Gastrointestinal Microbiome; D006801:Humans; D008603:Mental Health; D019936:Probiotics / Q000627:therapeutic use*
keywords: Anxiety; Depression; Mental health; Probiotic supplementation; Systematic review