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Head-to-head evidence comparison — which supplement is right for you?
Magnesium and Vitamin B12 are closely matched across evidence, studies, and safety.
Verdict
Likely helps
13 of 17 studies with measurable effects showed benefit.
Top outcomes
Verdict
Probably helps
16 of 23 studies with measurable effects showed benefit.
Top outcomes
Shared outcomes (2)
Outcomes where both Magnesium and Vitamin B12 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
500-1000mcg daily for maintenance; higher for deficiency
Morning (may be energizing), With or without food
Methylcobalamin (sublingual)
1-2 weeks
1-2 weeks
1 week
Immediate
2-4 weeks
4-8 weeks
Weeks to months
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.
Efficacy of different routes of vitamin B12 supplementation for the treatment of patients with vitamin B12 deficiency: A systematic review and network meta-analysis
Irish journal of medical science (2024) · Meta analysis · n=4275
Regarding the hemoglobin level, the pooled effect sizes showed no difference between all routes of administration that could reach statistical significance.
Dosage exploration of combined B-vitamin supplementation in stroke prevention: a meta-analysis and systematic review
The American journal of clinical nutrition (2024) · Meta analysis · n=76664
In areas without and with partial folic acid fortification, combined B-vitamin supplementation significantly reduced the risk of stroke by 34% [RR: 0.66; 95% confidence interval (CI): 0.50, 0.86] and 11% (RR: 0.89; 95% CI: 0.79, 1.00), respectively.
Vitamin Status in Patients with Phenylketonuria: A Systematic Review and Meta-Analysis
International journal of molecular sciences (2024) · Meta analysis · n=770
The effect sizes were expressed as standardised mean differences.
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.
AI-estimated from published studies. Interpret as directional guidance.
Both Magnesium and Vitamin B12 are closely matched — the best choice depends on your specific health goals.
For bone health, Magnesium has a higher relevance score (85 vs 75).
No known interactions between Magnesium and Vitamin B12 have been documented in our database. However, always consult a healthcare provider before combining supplements.