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Head-to-head evidence comparison — which supplement is right for you?
Magnesium wins 2 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
Verdict
Likely helps
13 of 17 studies with measurable effects showed benefit.
Top outcomes
Verdict
Mixed evidence
4 of 9 studies with measurable effects showed benefit.
Top outcomes
Shared outcomes (1)
Outcomes where both Magnesium and St. John's Wort have evidence — compare verdict strength side-by-side.
200-350mg elemental magnesium daily
Evening for sleep/relaxation (glycinate), Morning for energy (malate), Anytime (citrate)
Depends on goal - see notes
300mg 3x daily (900mg total)
With meals, Divided into 2-3 doses
Standardized extract (0.3% hypericin)
1-2 weeks
1-2 weeks
1 week
Immediate
4-6 weeks
4-8 weeks
During use
First 1-2 weeks
Magnesium supplementation in pregnancy
The Cochrane database of systematic reviews (2014) · Meta analysis · n=9090
Women receiving magnesium were significantly less likely to require hospitalisation during pregnancy (RR 0.65, 95% CI 0.48 to 0.86; three trials, 1158 women).Of the 10 trials included in the review, only two were judged to be of high quality overall.
Magnesium Supplementation and Blood Pressure: A Systematic Review and Meta-Analysis
Hypertension (2025) · Meta analysis · n=2709
38 RCTs with 2709 participants analyzed
Magnesium and Potassium Supplementation for Systolic Blood Pressure Reduction in the General Normotensive Population: A Systematic Review and Subgroup Meta-Analysis for Optimal Dosage and Treatment Length
Nutrients (2024) · Meta analysis
Both supplements demonstrated greater reductions in SBP for the general population at lower dosages and longer treatment durations.
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-analysis of 38 RCTs with 2709 participants showing -7.68 mmHg reduction in hypertensive individuals. Effects are greatest in those with hypomagnesemia. Limited evidence in normotensive populations.
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.
Magnesium has a higher evidence score (8.5/10 vs 7.8/10) and wins in 2 of 3 categories.
For support mood, St. John's Wort has a higher relevance score (92 vs 60).
No known interactions between Magnesium and St. John's Wort have been documented in our database. However, always consult a healthcare provider before combining supplements.