Effect of Probiotics on Psychiatric Symptoms and Central Nervous System Functions in Human Health and Disease: A Systematic Review and Meta-Analysis

Abstract

Background: The gut microbiota impacts on central nervous system (CNS) function via the microbiota–gut–brain axis. Thus, therapeutics targeting the gut microbiota such as probiotics have the potential for improving mental health. This meta-analysis synthesizes the evidence regarding the impacts of probiotics on psychological well-being, psychiatric symptoms and CNS functioning. Methods: The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were applied for executing this review using the databases PubMed, Web of Science and Cochrane Library. The data were summarized at qualitative and quantitative level. Results: Fifty-four randomized placebo-controlled studies were included, of which 30 were eligible for meta-analysis. If investigated, the probiotics mostly exerted effects on CNS function. Most probiotics did not affect mood, stress, anxiety, depression and psychiatric distress when compared to placebo at the qualitative level. At quantitative level, depression and psychiatric distress improved slightly in the probiotic condition (depression: mean difference −0.37 (95% CI: −0.55, −0.20); p ≤ 0.0001; psychiatric distress: mean difference −0.33 (95% CI: −0.53, −0.13); p = 0.001). Conclusions: To date it is unclear to which extent and in which specific areas next generation probiotics selected and developed for their ability to improve psychiatric condition and potentially other CNS functions are promising.

Gut Microbiome: A Brief Review on Its Role in Schizophrenia and First Episode of Psychosis

“…Although certain studies have demonstrated their beneficial psychological effects, such as anxiolytic-like activity [24], and the literature has outlined the great potential positive impact of probiotics and emerging psychobiotics on mental disorders [23], the outcomes of treatment trials with probiotics have been somewhat insignificant, both for depressive symptoms [25] and psychotic symptoms [26]. On a similar note, although 'gut biotics' [27], such as prebiotics and synbiotics, could be potentially helpful in treating mental health disorders and particularly depression and anxiety [27][28][29], recent meta-analytic data indicate that there is not yet strong enough evidence to support the inclusion of probiotic, prebiotic and symbiotic supplements in treatment guidelines for depression [30]. At the same time, research around paraprobiotics, proteobiotics and postbiotics is still very limited [27], with a need for much more data from randomised controlled trials.…”

Differences in the Perception of Dietary Supplements between Dietary Supplement/Medicine Users and Non-Users

“…Indeed, some people use dietary supplements for the prevention of diseases. At this time, there are many studies that examine the effect of dietary supplements, such as probiotics [ 46 , 47 ], B-complex multivitamin/mineral supplementation [ 48 ], magnesium [ 49 ], and omega-3 [ 50 ] for anxiety, but there are few reports on whether anxiety towards health encourages people to use dietary supplements. Anxiety was associated with dietary supplement/complementary alternative medicine in cancer survivors [ 51 ], women with early breast cancer [ 52 ], and patients with liver disease [ 53 ] but not healthy subjects.…”

The Role of Psychobiotics to Ensure Mental Health during the COVID-19 Pandemic—A Current State of Knowledge

“…Administration of the 4-week multispecies probiotics intervention ( Bifidobacterium bifidum W23, Bifidobacterium lactis W52, Lactobacillus acidophilus W37, Lactobacillus brevis W63, Lactobacillus casei W56, Lactobacillus salivarius W24, and Lactococcus lactis W19 and W58) resulted in a significant reduction in overall cognitive reactivity to sad mood, which was largely accounted for by reduced rumination and aggressive thoughts [ 91 ]. To confirm the hypothesis that probiotics administration is associated with a significant reduction in depression, several systematic reviews and meta-analyses of the existing evidence were conducted [ 97 , 98 , 99 , 100 , 101 , 102 , 103 , 104 , 105 , 106 , 107 , 108 ]. The evidence for probiotics alleviating depressive symptoms is compelling, which is confirmed by the secondary evidence found, but additional double-blind randomized control trials in clinical populations are necessitated to further assess efficacy.…”