L-Theanine ： Attention & Focus Difficulties
B エビデンス 少なくとも1件のランダム化試験がこれを支持しており、おおむね一貫した結果が得られています。The L-theanine + caffeine combination is one of the most replicated nootropic pairings in cognitive research, consistently showing improvements in attention, task switching, and alertness without jitteriness.
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B
結論
The L-theanine + caffeine combination is one of the most replicated nootropic pairings in cognitive research, consistently showing improvements in attention, task switching, and alertness without jitteriness.
Key Study Findings
Systematic Review
Efficiency of Different Supplements in Alleviating Symptoms of ADHD with or Without the Use of …
Dose: None
vs: Placebo or methylphenidate
Outcome: ADHD symptom severity (inattention, hyperactivity)
効果: None
None
対象集団: ADHD patients (systematic review of supplements)
Systematic Review
The effects of L-theanine supplementation on the outcomes of patients with mental disorders: a systematic …
Dose: None
vs: None
Outcome: Anxiety symptoms
効果: None
None
対象集団: Schizophrenia patients
Systematic Review
Association between sleep pattern and pharmacological treatment in children with attention deficit disorder with hyperactivity: …
Dose: None
vs: None
Outcome: sleep quality
効果: None
None
対象集団: Children
Randomized Controlled Trial
4.3 weeks
Single-blind
Assessing brain function in stressed healthy individuals following the use of a combination of green …
Dose: None
vs: placebo
Outcome: Brain response to stress and quality of life
効果: None
p = 0.001
対象集団: Chronically stressed but healthy subjects
Systematic Review
884 weeks
The Cognitive-Enhancing Outcomes of Caffeine and L-theanine: A Systematic Review.
Dose: 9.4%
vs: None
Outcome: None
効果: None
None
対象集団: None
Randomized Controlled Trial
Effects of L-theanine-caffeine combination on sustained attention and inhibitory control among children with ADHD: a …
Dose: 2.5 mg/kg
vs: Placebo
Outcome: None
効果: None
p = 0.040
対象集団: Children with ADHD
Key Statistics
20
研究数
1500
参加者数
↑
Positive
B
グレード
Referenced Papers
Efficiency of Different Supplements in Alleviating Symptoms of ADHD with or Without the Use of Stimulants: A Systematic Review.
Systematic Review
Nutrients
2025
1 件の引用
The effects of L-theanine supplementation on the outcomes of patients with mental disorders: a systematic review.
Systematic Review
BMC psychiatry
2024
12 件の引用
Association between sleep pattern and pharmacological treatment in children with attention deficit disorder with hyperactivity: a systematic review.
Systematic Review
Revista paulista de …
2023
3 件の引用
Frontiers in nutrition
2023
3 件の引用
Cureus
2021
20 件の引用
Scientific reports
2020
34 件の引用
Journal of psychiatric …
2019
46 件の引用
Acta neuropsychiatrica
2017
84 件の引用
Alternative medicine review …
2011
82 件の引用
Dosage & Usage
mg = milligrams · mcg = micrograms (1,000× smaller) · IU = International Units
一般的な使用量
- general:
- 100-200 mg/day
- withcaffeine:
- 200 mg L-theanine + 100 mg caffeine
上限量： 900 mg/day (no adverse effects observed in studies)
研究で検討された用量
| 用量 | 期間 | 効果 | N |
|---|---|---|---|
| None | -- | Mixed | -- |
| None | -- | Positive | -- |
| None | -- | Mixed | -- |
| None | 4.3 weeks | Positive | -- |
| 9.4% | 884 weeks | Positive | -- |
| 2.5 mg/kg | -- | Negative | -- |
| 450-900 mg L-theanine daily | 10 weeks | Neutral | 46 |
| 250 mg/day | 8 weeks | Positive | 20 |
推奨摂取タイミング： Morning or as needed; rapid onset (30-60 minutes)
Safety & Side Effects
報告されている副作用
- ⚠ Generally very well-tolerated
- ⚠ Mild drowsiness in sensitive individuals
- ⚠ Mild headache (rare)
既知の相互作用
- ● Antihypertensive drugs (may enhance blood pressure lowering)
- ● Stimulant medications (counteracts some stimulant side effects)
- ● Sedative medications (additive calming effects)
耐容上限摂取量： 900 mg/day (no adverse effects observed in studies)
サプリメントの摂取を開始する前に、必ず医療専門家にご相談ください。
Frequently Asked Questions
Does L-Theanine help with Attention & Focus Difficulties?
Based on 20 studies with 1,500 participants, there is moderate evidence from clinical studies that L-Theanine may support Attention & Focus Difficulties management. Our evidence grade is B (Good Evidence).
How much L-Theanine should I take for Attention & Focus Difficulties?
Studies have used various dosages. A commonly studied range is 100-200 mg/day. Always consult your healthcare provider before starting any supplement regimen.
Are there side effects of L-Theanine?
Reported side effects may include Generally very well-tolerated, Mild drowsiness in sensitive individuals, Mild headache (rare). Most side effects are mild and dose-dependent. Consult your doctor if you experience any adverse reactions.
How strong is the evidence for L-Theanine and Attention & Focus Difficulties?
We rate the evidence as Grade B (Good Evidence). This rating is based on 20 peer-reviewed studies with 1,500 total participants. The overall direction of effect is positive.
Related Evidence
に関する他の成分： Attention & Focus Difficulties
L-Theanine 他の症状・状態について
References
- [1] Shatha Al Shahab et al.. Nutrients. 2025. Efficiency of Different Supplements in Alleviating Symptoms of ADHD with or Without the Use of Stimulants: A Systematic Review. doi:10.3390/nu17091482 PubMed
- [2] Reza Moshfeghinia et al.. BMC Psychiatry. 2024. The effects of L-theanine supplementation on the outcomes of patients with mental disorders: a systematic review. doi:10.1186/s12888-024-06285-y PubMed
- [3] Nathalia Sena Rocha et al.. Rev Paul Pediatr. 2023. Association between sleep pattern and pharmacological treatment in children with attention deficit disorder with hyperactivity: a systematic review. doi:10.1590/1984-0462/2023/41/2022065 PubMed
- [4] Gisèle Pickering et al.. Front Nutr. 2023. Assessing brain function in stressed healthy individuals following the use of a combination of green tea, Rhodiola, magnesium, and B … doi:10.3389/fnut.2023.1211321 PubMed
- [5] Anas Anas Sohail et al.. Cureus. 2021. The Cognitive-Enhancing Outcomes of Caffeine and L-theanine: A Systematic Review. doi:10.7759/cureus.20828 PubMed
- [6] Chanaka N Kahathuduwa et al.. Sci Rep. 2020. Effects of L-theanine-caffeine combination on sustained attention and inhibitory control among children with ADHD: a proof-of-concept neuroimaging RCT. doi:10.1038/s41598-020-70037-7 PubMed
- [7] Jerome Sarris et al.. J Psychiatr Res. 2019. L-theanine in the adjunctive treatment of generalized anxiety disorder: A double-blind, randomised, placebo-controlled trial. doi:10.1016/j.jpsychires.2018.12.014 PubMed
- [8] Shinsuke Hidese et al.. Acta Neuropsychiatr. 2017. Effects of chronic l-theanine administration in patients with major depressive disorder: an open-label study. doi:10.1017/neu.2016.33 PubMed
- [9] Michael R Lyon et al.. Altern Med Rev. 2011. The effects of L-theanine (Suntheanine®) on objective sleep quality in boys with attention deficit hyperactivity disorder (ADHD): a randomized, double-blind, … PubMed
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