Exploring neurotransmitter regulation following probiotic supplementation in adults with subthreshold depression: A secondary analysis of a randomized controlled trial
Abstract
OBJECTIVE
This secondary analysis examined changes in plasma concentrations of gamma-aminobutyric acid (GABA) and serotonin following multi-species probiotic supplementation versus placebo in Australian adults with subthreshold depression and investigated the potential relationships between neurotransmitter changes and mental health outcomes.
METHODS
In a 12-week, double-blind, randomized, placebo-controlled trial, 39 participants took daily doses of one capsule (i.e., placebo or probiotic) containing 4 × 109 CFU of lyophilized strains: Limosilactobacillus fermentum LF16 (DSM26956), Lacticaseibacillus rhamnosus LR06 (DSM21981), Lactiplantibacillus plantarum LP01 (LMG P-21021) and Bifidobacterium longum 04 (DSM23233). Data collected at baseline, 6 and 12 weeks of intervention included validated self-reported questionnaires measuring psychometric symptom severity and plasma concentrations of two neurotransmitters (i.e., GABA and serotonin). Repeated measures ANOVA and mediation analyses were performed.
RESULTS
Plasma serotonin concentrations significantly increased at 6 weeks in both probiotic and placebo groups (2.5 (95% CI 1.3; 3.8) and 2.3 (95% CI 1.0; 3.6), respectively) but only in the placebo group (4.9 [95% CI 1.5; 8.3]) at 12 weeks. No significant changes were observed for plasma GABA concentrations.
CONCLUSIONS
An inverse regulation, leading to decreased plasma serotonin levels, was observed after 6 weeks of supplementation with the probiotic formulation. As evidenced…
How strong is the evidence?
Evidence Hub reads this as a secondary / pooled analysis, done in people. Its evidence level is 3 of 5 (Moderate · trial / cohort / secondary analysis). Trials without a large randomized design, cohorts and secondary analyses give moderate evidence. Reported size: 39 participants or records.
Read the paper
Related studies
- Improving sleep quality leads to better mental health: A meta-analysis of randomised controlled trials
- Tocilizumab in patients with severe COVID-19: a retrospective cohort study
- A new aging measure captures morbidity and mortality risk across diverse subpopulations from NHANES IV: A cohort study
- Fruit, vegetable, and legume intake, and cardiovascular disease and deaths in 18 countries (PURE): a prospective cohort study
- Are noise and air pollution related to the incidence of dementia? A cohort study in London, England
- Long COVID symptoms and duration in SARS-CoV-2 positive children — a nationwide cohort study
Go deeper in Evidence Hub
Evidence Hub adds a study data sheet (design, sample size, evidence level, key numbers), an AI summary and a chat grounded in the paper's text.