What is L-Theanine (L-Theanine)?
L-Theanine is a non-proteinojenic amino acid primarily found in the tea plant (Camellia sinensis). It has been shown to cross the blood-brain barrier, affect neurotransmitter levels such as GABA and dopamine in the central nervous system, and increase alpha brain wave activity associated with relaxed alertness. It is generally associated with a 'calm but alert' mental state.
- CAS number: 3081-61-6
- Molecular formula: C₇H₁₄N₂O₃
What Does L-Theanine Do? Why Is It Used?
L-Theanine is valued in functional beverage and pre-workout formulations, especially when combined with caffeine, for providing focus and calm alertness. Its association with relaxation without sedation and its good tolerance even at high doses make it a formulation-friendly compound. However, it should be noted that health claims cannot be made (EFSA rejection).
Usage as a Sports Nutrition Ingredient
The following information is based on sports nutrition research (ISSN position statements, randomized controlled trials, and meta-analyses); the level of evidence is clearly specified for each item.
- Caffeine + Theanine: Focus and Calm Alertness (Pre-workout Synergy): The most supported use in sports nutrition is in combination with caffeine. Randomized controlled trials have shown that the combination improves cognitive measures such as attention switching and subjective alertness (PMID 18681988; PMID 21040626). Level of evidence: moderate for cognitive/attention outcomes; limited for direct physical performance (strength/endurance) outputs.
- Mitigating Caffeine Side Effects: It is suggested that Theanine somewhat buffers caffeine-induced restlessness, tremors, and blood pressure increases; this is the rationale for 'cleaner energy' in pre-workout formulations. Evidence: moderate/limited, mostly based on cognitive and subjective measures.
- Pre-competition Anxiety: Some studies have reported reductions in subjective stress/anxiety measures; it provides a theoretical basis for managing pre-competition tension in sports, but direct evidence for sports performance is weak.
Forms and Differences
L-Theanine is available in different forms; form selection is made based on bioavailability, stability, and intended use:
- L-Theanine (natural, green tea derived): It is the biologically active L-form naturally found in green tea (Camellia sinensis) leaves. This isomer, which occurs naturally in the body, is used in supplements.
- Suntheanine (fermentation/enzymatic L-theanine): Pure L-isomer theanine produced enzymatically (e.g., the Suntheanine brand). It is a standardized form used in most clinical studies; unlike racemic D/L mixtures, it is the pure L-form.
Usage in Dietary Supplements
- Combination with Caffeine (Focus): The most common use is taken together with caffeine. Clinical studies have typically shown measurable improvements in attention switching (task-switching) and subjective alertness with a combination of 97-100 mg L-theanine + 40-50 mg caffeine (Owen 2008; Giesbrecht 2010).
- Relaxation and Subjective Stress: Used alone at a dose of 200 mg for relaxation purposes. Some randomized studies have reported improvements in stress-related symptoms and subjective relaxation measures; however, the level of evidence is moderate and variable.
- Sleep Support: Evening use to aid sleep is common; however, L-theanine is not sedative, and its direct effect on initiating sleep is supported by weak evidence. The effect is more often explained by pre-sleep relaxation.
Usage in the Food Industry
- Functional Beverages: Used as an additive in relaxation beverages, tea-based functional beverages, and caffeinated products positioned as 'calm energy' (caffeine-theanine combination). It is water-soluble and has a neutral-light umami taste.
- Tea and Umami Enhancement: L-theanine is one of the main components of the characteristic umami (brothy) taste of green tea; it is evaluated for flavor and positioning in premium tea and functional food formulations.
Effects on Health
- Relaxation and Alpha Wave Activity: In EEG studies, L-theanine increased alpha brain waves associated with relaxed alertness without causing sedation; this is the neurophysiological basis for the feeling of relaxation.
- Attention and Cognitive Function (with Caffeine): Improvements in attention switching and alertness measures have been shown when taken with caffeine; the cognitive benefit when taken alone is small/inconsistent.
- Neurotransmitter Modulation: It is suggested that it modulates systems such as GABA, dopamine, and serotonin, and binds to glutamate receptors with low affinity — this is the presumed mechanism for its relaxation and stress-buffering effects.
Status of Health Claims (EFSA) — Transparent Information
EFSA (2011, Journal 2011;9(6):2238) has decided that a cause-and-effect relationship could NOT be established for claims regarding the improvement of cognitive function, alleviation of psychological stress, maintenance of normal sleep, and reduction of menstrual discomfort for green tea L-theanine; these claims were REJECTED. In 2018, regarding black tea and attention claims, EFSA attributed the possible effect more to CAFFEINE content than to theanine. There is no authorized (approved) health claim for L-theanine in the EU.
Usage Limits and Safety
- Typical Usage Dose: Typical supplement dose is 100-200 mg/day; in combination with caffeine, it is generally 97-100 mg. Single doses of 200-400 mg have been well tolerated in studies.
- Upper Limit of Intake (UL): There is NO established Tolerable Upper Intake Level (UL) (honest disclosure). It is generally well tolerated; theoretical interactions with blood pressure-lowering medications and effects on heart/blood pressure when combined with caffeine should be considered.
- Turkish Legislation (Sports Foods / TETGK): The Turkish Food Codex Dietary Supplements Regulation recognizes amino acids as supplement ingredients and requires the L-form; no specific numerical upper limit has been published for L-theanine in the Regulation (NOT MADE UP — does not exist). The product falls under general supplement legislation and notification procedures.
Warning: Theoretical interactions with sedatives and antihypertensives may occur; palpitations/insomnia may be seen in sensitive individuals in combinations containing caffeine. Data is limited during pregnancy/lactation.
Technical Specifications
| Parameter | Value |
|---|---|
| Moisture | ≤5.0 % |
| Total Heavy Metals | ≤10 ppm |
| E. Coli | Negative in 10 g |
| Salmonella | Negative in 25 g |
| Solubility | Water Soluble |
Scientific Studies
The following independent researches relate to the sports performance, bioavailability, and effects of this compound (study types are specified):
- PubMed 18681988 — Combined effects of L-theanine and caffeine on cognitive performance and mood
- PubMed 21040626 — L-theanine and caffeine combination improves cognitive performance and increases subjective alertness
Technical Documents and Supply — Asuka Kimya
You can contact Asuka Kimya for SDS, TDS, CoA and supply conditions for L-Theanine.
References
- efsa.onlinelibrary.wiley.com
- efsa.onlinelibrary.wiley.com
- academic.oup.com
- pubmed.ncbi.nlm.nih.gov
- pubmed.ncbi.nlm.nih.gov
The usage, sports nutrition, and health information on this page have been compiled from official legislation/institution sources (EFSA, NIH ODS, ISSN, Turkish Food Codex Sports Foods / Dietary Supplements Regulation) and independent scientific publications (PubMed). The product is a food supplement/sports nutrition raw material; it does not aim to diagnose or treat diseases.