Abstract
The human gut microbiome influence on brain function and mental health is an emerging area of intensive research. Animal and human research indicates adolescence as a sensitive period when the gut-brain axis is fine-tuned, where dietary interventions to change the microbiome may have long-lasting consequences for mental health. This study reports a systematic review and meta-analysis of microbiota-targeted (psychobiotics) interventions on anxiety in youth, with discussion of a consultation on the acceptability of psychobiotic interventions for mental health management amongst youth with lived experience. Six databases were searched for controlled trials in human samples (age range: 10–24 years) seeking to reduce anxiety. Post intervention outcomes were extracted as standard mean differences (SMDs) and pooled based on a random-effects model. 5416 studies were identified: 14 eligible for systematic review and 10 eligible for meta-analysis (total of 324 experimental and 293 control subjects). The meta-analysis found heterogeneity I2 was 12% and the pooled SMD was −0.03 (95% CI: −0.21, 0.14), indicating an absence of effect. One study presented with low bias risk, 5 with high, and 4 with uncertain risk. Accounting for risk, sensitivities analysis revealed a SMD of −0.16 (95% CI: −0.38, 0.07), indicative of minimal efficacy of psychobiotics for anxiety treatment in humans. There is currently limited evidence for use of psychobiotics to treat anxiety in youth. However, future progress will require a multidisciplinary research approach, which gives priority to specifying mechanisms in the human models, providing causal understanding, and addressing the wider context, and would be welcomed by anxious youths.
Highlights
IntroductionAltering the gut microbiota with nutritional therapeutics such as psychobiotics (i.e. active compounds such as probiotics and prebiotics) shows promise in treating mental health problems such as depression and anxiety
Altering the gut microbiota with nutritional therapeutics such as psychobiotics shows promise in treating mental health problems such as depression and anxiety
The Bifidobacterium family is linked to GABA expression in the brain, whereas the Enterococcus and Streptococcus families are shown to produce serotonin, and Lactobacillus are linked to GABA and acetylcholine[12]
Summary
Altering the gut microbiota with nutritional therapeutics such as psychobiotics (i.e. active compounds such as probiotics and prebiotics) shows promise in treating mental health problems such as depression and anxiety. Recent research on psychobiotics as active ingredients in host physiology shows influence on the nervous system, consequentially shaping psychological processes, behaviour and exerting health benefits in psychiatric. The Bifidobacterium family is linked to GABA expression in the brain, whereas the Enterococcus and Streptococcus families are shown to produce serotonin, and Lactobacillus are linked to GABA and acetylcholine[12]. Brevis and Bifidobacterium (B.) dentium increased GABA concentrations in-vitro, a finding which was replicated in an in-vivo model which showed that a L. brevis ingested strain regulated emotional behavioural and central GABA receptor expression in a mouse model[1].
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