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Head-to-head evidence comparison — which supplement is right for you?
Probiotics wins 1 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
Verdict
Probably helps
18 of 26 studies with measurable effects showed benefit.
Top outcomes
Verdict
Mixed evidence
4 of 9 studies with measurable effects showed benefit.
Top outcomes
Shared outcomes (2)
Outcomes where both Probiotics and St. John's Wort have evidence — compare verdict strength side-by-side.
10-20 billion CFU
With or without food (strain-dependent), Same time daily for consistency
Capsules with multiple strains
300mg 3x daily (900mg total)
With meals, Divided into 2-3 doses
Standardized extract (0.3% hypericin)
2-4 weeks
4-8 weeks
4-8 weeks
First 1-2 weeks
4-6 weeks
4-8 weeks
During use
First 1-2 weeks
Preventive Effect of Probiotics on Oral Mucositis Induced by Cancer Treatment: A Systematic Review and Meta-Analysis
International journal of molecular sciences (2022) · Meta analysis · n=708
Three trials using Lactobacilli-based probiotics reported that the incidence of oral mucositis in the probiotic group was significantly low (risk ratio [RR] = 0.84, 95% confidence interval [CI] = 0.77−0.93, p = 0.0004).
Probiotics for treating acute infectious diarrhoea
The Cochrane database of systematic reviews (2020) · Meta analysis · n=12127
Effect size was similar in the sensitivity analysis and marked heterogeneity persisted.
Probiotics for the prevention of Clostridium difficile-associated diarrhea in adults and children
The Cochrane database of systematic reviews (2017) · Meta analysis · n=9955
A complete case analysis (i.e. participants who completed the study) among trials investigating CDAD (31 trials, 8672 participants) suggests that probiotics reduce the risk of CDAD by 60%.
St John's wort for major depression
Cochrane Database of Systematic Reviews (2008) · Meta analysis · n=5489
As effective as standard antidepressants for mild-moderate depression
Efficacy of Pharmacological Interventions in Milder Depression: A Systematic Review and Meta-Analysis
Neuropsychopharmacology reports (2025) · Meta analysis · n=1049
A meta-analysis found no significant difference in response rates between the two treatments (risk ratio [RR] = 0.96, 95% CI: 0.78-1.18) or dropout rates (RR = 1.08, 95% CI: 0.62-1.88).
Systematic Review and Network Meta-Analysis of the Effects of Plant Extracts on Cognitive Function and Quality of Life in Stroke Patients
Phytotherapy research : PTR (2025) · Meta analysis
John's Wort extract (SUCRA 71.2%) was the most effective in reducing NIHSS scores, Berberine (SUCRA 84.1%) was most effective in reducing mRS scores, and St.
Based on meta-analyses showing benefits for IBS and digestive symptoms. Effect sizes varied considerably between studies with low to very low certainty of evidence. Initial GI symptoms common when starting but typically resolve within 1-2 weeks.
Based on multiple meta-analyses (n>5000) showing efficacy comparable to SSRIs for mild-moderate depression. Effect plateau around 900-1200mg. Not effective for severe depression. Requires standardized extract (0.3% hypericin).
AI-estimated from published studies. Interpret as directional guidance.
Probiotics has a higher evidence score (9/10 vs 9/10) and wins in 1 of 3 categories.
For support mood, St. John's Wort has a higher relevance score (92 vs 60).
No known interactions between Probiotics and St. John's Wort have been documented in our database. However, always consult a healthcare provider before combining supplements.