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Head-to-head evidence comparison — which supplement is right for you?
L-Theanine and SAMe are closely matched across evidence, studies, and safety.
Verdict
Likely helps
3 of 4 studies with measurable effects showed benefit.
Top outcomes
Verdict
Mostly mechanism / observational
0 of 2 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
400-1600mg for mood; 600-1200mg for joints
On empty stomach, Morning and/or midday
Enteric-coated tablets (SAMe tosylate or butanedisulfonate)
30-60 minutes
30-60 minutes
30-60 minutes
Varies
2-6 weeks
4-8 weeks
4-8 weeks
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).
S-Adenosylmethionine for osteoarthritis of the knee or hip
The Cochrane database of systematic reviews (2009) · Meta analysis · n=656
For pain, the analysis indicated a small SMD of -0.17 (95% CI -0.34 to 0.01), corresponding to a difference in pain scores between SAMe and placebo of 0.4 cm on a 10 cm VAS, with no between trial heterogeneity (I(2) = 0).
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).
S-Adenosylmethionine (SAMe) for Liver Health: A Systematic Review
Nutrients (2024) · Systematic review · n=15
The most common doses were SAMe 1000 mg or 1200 mg per day with or without another treatment or natural supplement.
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.
Meta-analysis of 656 patients showed small effect size (SMD -0.17) corresponding to only 0.4cm improvement on 10cm pain scale. Effect is modest and barely reaches statistical significance threshold.
AI-estimated from published studies. Interpret as directional guidance.
Both L-Theanine and SAMe are closely matched — the best choice depends on your specific health goals.
For support mood, SAMe has a higher relevance score (90 vs 65).
No known interactions between L-Theanine and SAMe have been documented in our database. However, always consult a healthcare provider before combining supplements.