Head-to-head evidence comparison — which supplement is right for you?
L-Theanine wins 2 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
250-750mg
30-60 minutes before desired effect, Before bed for sleep, Before stressful events for anxiety
Capsules or powder
100-200mg
Morning with coffee for focus, Evening for relaxation, As needed for stress
Suntheanine® capsules or powder
30-60 minutes
30-60 minutes
30-60 minutes
30-60 minutes
30-60 minutes
30-60 minutes
Varies
Gamma aminobutyric acid (GABA) receptor agonists for acute stroke
The Cochrane database of systematic reviews (2018) · Meta analysis · n=3838
The most frequent adverse events related to chlormethiazole were somnolence (RR 4.56, 95% CI 3.50 to 5.95; two trials; 2527 participants; moderate-quality evidence) and rhinitis (RR 4.75, 95% CI 2.67 to 8.46; two trials; 2527 participants; moderate-quality evidence).
GABA Analogue HSK16149 in Chinese Patients With Diabetic Peripheral Neuropathic Pain: A Phase 3 Randomized Clinical Trial
JAMA network open (2024) · Rct · n=393
Of 725 randomized patients in the full-analysis set (393 men [54.2%]; mean [SD] age, 58.80 [9.53] years; 700 [96.6%] of Han Chinese ethnicity), 177 received placebo; 178, HSK16149, 40 mg/d; 179, HSK16149, 80 mg/d; 66, HSK16149, 120 mg/d; 63, HSK16149, 160 mg/d; and 62, pregabalin, 300 mg/d.
Neurometabolite differences in Autism as assessed with Magnetic Resonance Spectroscopy: A systematic review and meta-analysis
Neuroscience and biobehavioral reviews (2024) · Meta analysis
Data were extracted and grouped by metabolite, brain region and several other factors before calculation of standardised effect sizes.
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.
The Role of Supplements and Over-the-Counter Products to Improve Sleep in Children: A Systematic Review
International journal of molecular sciences (2023) · Systematic review
Although good sleep quality in children has been proven to be a key factor for optimal cognitive, physical and psychological development, a significant and ever-increasing percentage of the pediatric population suffers from sleep disorders.
L-Theanine has a higher evidence score (9/10 vs 8.5/10) and wins in 2 of 3 categories.
For reduce anxiety & stress, L-Theanine has a higher relevance score (85 vs 75).
No known interactions between GABA and L-Theanine have been documented in our database. However, always consult a healthcare provider before combining supplements.