Related Experiment Video
Updated: Jan 24, 2026
Author Spotlight: Evaluating the Adjuvant Efficacy and Safety of Angong Niuhuang Pill in Viral Encephalitis Treatment
Published on: April 19, 2024
Efficacy of probiotic intervention in unmedicated depression: a systematic review and meta-analysis
Liu Haiyan1, Wang Dan1, Wan Xiaochao1
1The 82nd Army Group Hospital of the People's Liberation Army (PLA), Baoding, Hebei, China.
Objective:
To assess the independent efficacy and safety of probiotics in unmedicated adults with depression, with a focus on studies approximating monotherapy conditions.
Methods:
This systematic review and meta-analysis followed PRISMA 2020 guidelines and was registered with PROSPERO (CRD420251015474). Four major databases were searched through March 2025 for randomized controlled trials (RCTs) investigating probiotic monotherapy in individuals with depression not receiving psychotropic treatment. All forms of standardized probiotic formulations (e.g., capsules, sachets) were eligible. The primary outcome was the change in validated depression rating scales. Standardized mean differences (SMDs) were synthesized using a random-effects model. Sensitivity and subgroup analyses addressed intervention type, assessment method (self-report vs. clinician-rated scales), and funding source. Safety outcomes were systematically assessed.
Results:
Six RCTs with 341 randomly assigned participants (169 probiotic, 172 placebo) were included. Probiotic monotherapy was associated with a small but statistically significant reduction in depressive symptoms (SMD = -0.38, 95% CI: -0.57 to -0.18, p = 0.0002, I² = 51%). Exploratory subgroup analysis indicated potential greater benefit in mild to moderate depression compared to major depressive disorder. Sensitivity analysis excluding industry-funded trials or studies with adjunctive agents resulted in non-significant findings (SMD = -0.21, 95% CI: -0.65 to 0.23, p = 0.35). Minor adverse events were reported, with no significant difference between groups and no serious adverse events.
Conclusion:
Probiotic monotherapy may provide modest improvement in depressive symptoms and is generally safe for unmedicated individuals with mild to moderate depression. Given the small effect size, possible industry-related bias, and study heterogeneity, these findings should be interpreted cautiously. Larger, independently-funded RCTs are warranted to confirm efficacy and clarify mechanisms.
Systematic Review Registration:
https://www.crd.york.ac.uk/prospero/, iidentifier CRD420251015474.
Related Concept Videos
01:05Long-term Depression
01:10Review and Preview
Percentiles are a type of fractile that partition data into...
01:13Review and Preview
03:12Freezing Point Depression and Boiling Point Elevation
The boiling point of a liquid is the temperature at which its vapor pressure is equal to ambient atmospheric pressure. Since the vapor pressure of a solution is lowered due to the presence of nonvolatile solutes, it stands to reason that the solution’s boiling point will subsequently be increased. Vapor pressure increases with temperature, and so a solution will require a higher temperature than will pure solvent to achieve any given vapor pressure, including one...
01:28Depressants
Alcohol is a common depressant that can induce a sense of relaxation and reduced inhibition at low doses. Contrary to its occasional...
01:03Nursing Interventions I: Taxonomy of Nursing Interventions
A nursing intervention is a treatment or action based on scientific concepts and knowledge from the nursing, behavioral, and physical sciences. Identifying and prioritizing nursing interventions based on the desired outcome...