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Head-to-head evidence comparison — which supplement is right for you?
Myo-Inositol and St. John's Wort are closely matched across evidence, studies, and safety.
Verdict
Probably helps
5 of 10 studies with measurable effects showed benefit.
Top outcomes
Verdict
Mixed evidence
4 of 9 studies with measurable effects showed benefit.
Top outcomes
2-4g daily for PCOS; up to 12-18g for anxiety
Divided doses with meals, Morning and evening
Myo-inositol powder
300mg 3x daily (900mg total)
With meals, Divided into 2-3 doses
Standardized extract (0.3% hypericin)
3-6 months
4-6 weeks
2-3 months
Initial use or high doses
4-6 weeks
4-8 weeks
During use
First 1-2 weeks
Antenatal dietary supplementation with myo-inositol for preventing gestational diabetes
The Cochrane database of systematic reviews (2023) · Meta analysis · n=1319
For the primary neonatal outcomes, only one study measured the risk of a large-for-gestational-age infant and found myo-inositol was associated with both appreciable benefit and harm (RR 1.40, 95% CI 0.65 to 3.02; 1 study, 234 infants; low-certainty evidence).
Inositol Nutritional Supplementation for the Prevention of Gestational Diabetes Mellitus: A Systematic Review and Meta-Analysis of Randomized Controlled Trials
Nutrients (2022) · Meta analysis · n=1321
Pooled results were expressed as relative risk (RR) or mean difference (MD) with a 95% confidence interval (95% CI).
Short period-administration of myo-inositol and metformin on hormonal and glycolipid profiles in patients with polycystic ovary syndrome: a systematic review and updated meta-analysis of randomized controlled trials
European review for medical and pharmacological sciences (2022) · Meta analysis · n=612
Compared with metformin, the suitable supplemental dosage of myo-ins may be helpful in lowering levels of TG and avoiding adverse events (AEs).
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 multiple meta-analyses showing improved menstrual regularity and ovulation in PCOS. Evidence quality varies across studies with some showing minimal differences vs placebo. 4g daily most commonly studied dose.
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.
Both Myo-Inositol and St. John's Wort are closely matched — the best choice depends on your specific health goals.
For support mood, St. John's Wort has a higher relevance score (92 vs 90).
No known interactions between Myo-Inositol and St. John's Wort have been documented in our database. However, always consult a healthcare provider before combining supplements.