The Benefits of Probiotics on Depression: A Systematic Mini-Review
Authors:   PPCR Program, Harvard T.H. Chan School of Public Health, Boston, MA, USA, Caruso Rosario ,   Health Professions Research and Development Unit, IRCCS Policlinico San Donato, 20097 Milan, Italy,   Department of Biomedical Sciences for Health, University of Milan, 20122 Milan, Italy, Chamba Rospigliosi Jose Luis ,   PPCR Program, Harvard T.H. Chan School of Public Health, Boston, MA, USA, Checo Mariana ,   Investigaciones Biomedicas de Profamilia, Santo Domingo, Dominican Republic,   PPCR Program, Harvard T.H. Chan School of Public Health, Boston, MA, USA, Lima de Oliveira Lilia Maria ,   PPCR Program, Harvard T.H. Chan School of Public Health, Boston, MA, USA, Schulte Farina Giovani ,   University of Caxias do Sul, Caxias do Sul, Brazil,   PPCR Program, Harvard T.H. Chan School of Public Health, Boston, MA, USA, Parron Fernandes Karen Barros ,   School of Medicine, Pontifical Catholic University of Parana (PUCPR), Londrina, Brazil,   Department of Health Sciences, Université du Québec à Chicoutimi (UQAC), Saguenay, Canada,   PPCR Program, Harvard T.H. Chan School of Public Health, Boston, MA, USA, Jaldin-Pinto Angelica Valeria ,   PPCR Program, Harvard T.H. Chan School of Public Health, Boston, MA, USA, Link Naira ,   PPCR Program, Harvard T.H. Chan School of Public Health, Boston, MA, USA, Mercado Dominguez Aimee ,   PPCR Program, Harvard T.H. Chan School of Public Health, Boston, MA, USA, Meza-Venegas Joyce Alexandra ,   PPCR Program, Harvard T.H. Chan School of Public Health, Boston, MA, USA,   Massachusetts General Hospital, Cardiac Psychiatry Research Program, Boston, MA, USA, Mohamed Ibrahim ,   PPCR Program, Harvard T.H. Chan School of Public Health, Boston, MA, USA, Nirta Lauren ,   PPCR Program, Harvard T.H. Chan School of Public Health, Boston, MA, USA,   MediSpeak Communications, Bukgu, Busan, South Korea, Nishizawa Takuro Nishizawa ,   PPCR Program, Harvard T.H. Chan School of Public Health, Boston, MA, USA, Radi-Zahran Ibrahim Antonio ,   Universidad Francisco Marroquin, Guatemala City, Guatemala,   PPCR Program, Harvard T.H. Chan School of Public Health, Boston, MA, USA, Urja Prakrity ,   Faith Regional Cardiovascular Institute, Norfolk, NE, USA,   PPCR Program, Harvard T.H. Chan School of Public Health, Boston, MA, USA, Pimentel Vespasiano Celso Francisco ,   PPCR Program, Harvard T.H. Chan School of Public Health, Boston, MA, USA, Tamayo Arturo ,   PPCR Program, Harvard T.H. Chan School of Public Health, Boston, MA, USA,   The Max Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Canada
Published: July 2023

Introduction: Evidence from randomized controlled trials investigating the effects of probiotics on depression published in the last four years has not yet been synthesized. The current systematic mini-review aimed to summarize the impact of probiotics in adults diagnosed with major depression with mild, moderate, or severe symptoms using studies published after May 2018. Methods: A systematic literature search was conducted in PubMed, Web of Science, and Embase databases to identify randomized controlled trials that investigated the effect of any strain of probiotics alone or as an add-on therapy for the treatment of adult patients with mild, moderate, or severe symptoms of major depression and without other neurological and/or psychiatric disorders, published between May 2018 and August 2022. Data were extracted and qualitatively reviewed to determine the treatment effect. In addition, the quality of the methodology and risk of bias was assessed using the Cochrane risk-of-bias tool (RoB 2). Results: Five studies met the inclusion criteria. All were randomized, parallel-group, placebo-controlled, double-anonymized trials with probiotics administered as an add-on therapy for treating mild and moderate symptoms of major depression only. In total, 303 patients (18–65 years) were randomized and treated with probiotics for 1–3 months. Four studies showed positive treatment effects, while one showed no difference between groups. Discussion: There is encouraging evidence showing the potential beneficial effect of probiotics as an add-on treatment for patients with major depression with mild-to-moderate symptoms. However, future phase III trials are required to corroborate these results.