Overview
L-Theanine (γ-glutamylethylamide) is a non-proteinogenic amino acid primarily found in tea leaves, particularly green tea, and is recognized for its calming and cognitive-enhancing effects. It promotes relaxation without sedation by increasing alpha brain wave activity, which is associated with a state of wakeful relaxation and reduced anxiety [1][2][3]. Research indicates that L-theanine may improve sleep quality by reducing sleep onset latency and daytime dysfunction, likely through its anxiolytic properties rather than direct sedation [6]. It also supports cognitive function, especially attention and focus, particularly when combined with caffeine, due to synergistic effects on alertness and calmness [4]. Proposed mechanisms include modulation of neurotransmitters such as GABA, dopamine, and serotonin, and potential neuroprotective effects via antioxidant and anti-inflammatory pathways [1][2].
Dosage Guide
Therapeutic Doses
For treatment of specific conditions
Special Forms
Alternative forms for specific needs
Patented, pure form of L-theanine; clinically studied, enantiomerically pure (L-isomer only)
Clinical Notes
- L-theanine is generally well-tolerated with minimal side effects at recommended doses.
- No established RDA or UL; doses up to 400 mg/day appear safe in short-term studies.
- May enhance effects of sedatives or antihypertensive drugs; use with caution in patients on CNS depressants.
- Does not cause drowsiness during daytime; suitable for daytime use in anxiety and focus support.
- Ensure product contains pure L-theanine (Suntheanine® or equivalent) rather than tea extract with variable content.
Research
L-theanine contributes to cerebral protection from ischemia via antioxidant, anti-inflammatory, and antiatherogenic mechanisms.
L-theanine is among the phytochemicals with clinically demonstrable potential to support cognitive function and reduce cognitive decline.
L-theanine induces alpha brain waves and has anxiolytic effects, supporting initiation of high-quality sleep without side effects.
Acute L-theanine intake improves mood (calmness, alertness) and attention, especially when combined with caffeine.
L-theanine in green tea contributes to antioxidant effects with potential applications in periodontal health.
L-theanine supplementation significantly improves subjective sleep onset latency and daytime dysfunction in a meta-analysis of RCTs.
L-theanine is a key bioactive component of green tea linked to multiple health benefits, including neuroprotection and stress reduction.
L-theanine improves multiple subjective sleep outcomes in adults, including sleep latency and daytime function.
Products Containing L-Theanine(2 reports)
This supplement combines magnesium L-threonate, L-theanine, and apigenin to support cognitive function, relaxation, and metabolic health. The primary ingredients—magnesium and L-theanine—are dosed within clinically studied ranges and are associated with improved brain health, reduced anxiety, and enhanced sleep quality. Apigenin is included at a modest dose, potentially contributing antioxidant and anti-inflammatory effects, though human evidence remains limited.
HYDROXYCUT HARDCORE LIQUID HEAT is a thermogenic weight management supplement with caffeine and cayenne pepper extract as its primary active ingredients. These compounds are clinically shown to enhance metabolic rate, reduce energy intake, and support fat oxidation. The formulation includes supporting doses of B-vitamins and green coffee bean extract to complement energy metabolism and cardiovascular health.