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Head-to-head evidence comparison — which supplement is right for you?
Kava vs L-Theanine: they're closely matched on evidence (6 vs 6/10); they're alternatives for reduce anxiety & stress — the best pick depends on your goals. Take the 60-second quiz for a pick tailored to your goals.
Kava and L-Theanine are closely matched across evidence, studies, and safety.
Verdict
Probably helps
3 of 6 studies with measurable effects showed benefit.
Top outcomes
Verdict
Too few graded studies
1 of 1 studies with measurable effects showed benefit.
Top outcomes
Shared outcomes (1)
Outcomes where both Kava and L-Theanine have evidence — compare verdict strength side-by-side.
150-300mg kavalactones daily. The cited trials used 120 to 250 mg of kavalactones a day.
Evening for relaxation, 30-60 minutes before stressful events, Before bed for sleep
Water-extracted root powder or capsules
100-200mg
Morning with coffee for focus, Evening for relaxation, As needed for stress
Suntheanine® capsules or powder
and 6 more not shown
30-60 minutes
30-60 minutes
30-60 minutes
1-2 hours
30-60 minutes
30-60 minutes
30-60 minutes
Varies
Herbal medicines in the treatment of psychiatric disorders: 10-year updated review
Phytotherapy research : PTR (2018) · Systematic review
Other encouraging herbal medicines with preliminary evidence include Curcuma longa (turmeric) in depression, Withania somnifera (ashwagandha) in affective disorders, and Ginkgo biloba (ginkgo) as an adjunctive treatment in Schizophrenia.
GABA-modulating phytomedicines for anxiety: A systematic review of preclinical and clinical evidence
Phytotherapy research : PTR (2018) · Systematic review
An open-ended search to 5 July 2017 was conducted using MEDLINE (PubMed), Scopus, and Cochrane library online databases and performed in a stepped format from preclinical to clinical investigations.
Herbal medicine for insomnia: A systematic review and meta-analysis
Sleep medicine reviews (2015) · Meta analysis · n=1602
There was no statistically significant difference between any herbal medicine and placebo, or any herbal medicine and active control, for any of the thirteen measures of clinical efficacy.
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).
Single-dose trials of L-theanine alone. In a crossover trial of 27 young adults given 100, 200 and 400 mg (PMID 32777998), only 400 mg shortened the P3b attention signal, and no dose changed reaction time. In a crossover trial of 20 healthy men, 200 mg improved recognition reaction time (PMID 26869148). In a crossover trial, 250 mg alone raised headache ratings and lowered correct serial subtractions, and the benefits came with caffeine (PMID 18006208). Most cognitive gains in this literature are for L-theanine combined with caffeine, which this curve does not show. The 400 mg ceiling rests on an 8-week trial of 80 schizophrenia inpatients, where side effects at 400 mg a day matched placebo (PMID 37697164). No trial found a best dose.
AI-estimated from published studies. Interpret as directional guidance.
Both Kava and L-Theanine are closely matched — the best choice depends on your specific health goals.
For reduce anxiety & stress, Kava has a higher relevance score (90 vs 85).
No documented interaction was found in the data searched. This does not establish that this exact combination is safe.
What’s safe while nursing, the truth about milk-supply herbs, and what to avoid (it passes into milk).
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.
The right pick depends on your goals. Answer a few quick questions for a personalised recommendation — or dig into the full evidence on each.