Active ingredient ‘Better gut microbiome function’

Summary Background The human gut microbiome and its effect on brain function and mental health is emerging as an area of intensive research. Both animal and human research point towards adolescence as a sensitive period when the gut-brain axis is fine-tuned, and when we can use dietary intervention to change the microbiome, with long-lasting consequences for mental health. Here we report the results of a systematic review/meta-analysis of microbiota-targeted (psychobiotics) interventions on anxiety in youth, together with a summary of consultation work of youth with lived experience. Methods Seven databases were searched (no date cut-offs), and controlled trials in clinical and healthy human samples (age range: 10-24) seeking to reduce anxiety were included. All data on between group-differences post intervention and outcomes were extracted as standard mean differences (SMDs) and pooled together based on a random-effects model. Findings 5416 studies were identified, 14 were eligible for the qualitative summary, of which 10 were included in the meta-analyses (total of 324 experimental and 293 control subjects). The heterogeneity I 2 was12% and the pooled SMD was −0.04 (95% CI: −0.21, 0.14). One study presented with low bias risk whereas 5 with high and 4 with uncertain risk, accounting for that, sensitivities analysis revealed a SMD of −0.16 (95%CI: −0.39, 0.06). Interpretation 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.