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Head-to-head evidence comparison — which supplement is right for you?
L-Theanine vs Magnesium: they're closely matched on evidence (6 vs 8.5/10); they're alternatives for improve deep sleep quality — the best pick depends on your goals. Take the 60-second quiz for a pick tailored to your goals.
L-Theanine and Magnesium are closely matched across evidence, studies, and safety.
Verdict
Likely helps
4 of 5 studies with measurable effects showed benefit.
Top outcomes
Verdict
Likely helps
12 of 16 studies with measurable effects showed benefit.
Top outcomes
100-200mg
Morning with coffee for focus, Evening for relaxation, As needed for stress
Suntheanine® capsules or powder
200-350mg elemental magnesium daily
Evening for sleep/relaxation (glycinate), Morning for energy (malate), Anytime (citrate)
Depends on goal - see notes
30-60 minutes
30-60 minutes
30-60 minutes
Varies
1-2 weeks
1-2 weeks
1 week
Immediate
The effects of L-theanine consumption on sleep outcomes: A systematic review and meta-analysis
Sleep medicine reviews (2025) · Meta analysis · n=897
The findings indicate the potential use of L-theanine in the management of sleep disturbances; however, the lack of studies on "pure" L-theanine warrants further investigation.
Efficiency of Different Supplements in Alleviating Symptoms of ADHD with or Without the Use of Stimulants: A Systematic Review
Nutrients (2025) · Systematic review
The evidence revealed the potential use of supplements as complementary ADHD treatments under clinical guidance.
Analysis of the Effects of Known Sleep-Support Supplements in Relation to Life Habits, Sleep Conditions, and Sleep Problems
Nutrients (2023) · Rct · n=160
All the tested supplements were found to ameliorate sleep problems significantly (Analysis 1).
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.
Meta-analysis (n=897) and multiple RCTs support sleep benefits. Studies often used L-theanine in combination with other compounds, limiting pure L-theanine effect attribution. Effects include reduced sleep onset latency and improved subjective sleep quality.
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 L-Theanine and Magnesium are closely matched — the best choice depends on your specific health goals.
For improve deep sleep quality, Magnesium has a higher relevance score (90 vs 60).
No known interactions between L-Theanine and Magnesium have been documented in our database. However, always consult a healthcare provider before combining supplements.
The honest tier list — proven staples vs situational vs mostly marketing. The hub the other guides feed into.
Caffeine+L-theanine works; bacopa needs weeks; most "brain pills" are hype. The honest tier list.
Ashwagandha, L-theanine, magnesium, saffron — what actually helps stress, and the safety caveats.
Melatonin, magnesium, glycine, L-theanine — tiered by evidence, plus a wind-down timeline.
The right pick depends on your goals. Answer a few quick questions for a personalised recommendation — or dig into the full evidence on each.