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L-Theanine

Also known as: theanine, suntheanine

AAdequate Evidence8 studies referenced

Common dosage

100-200mg

Category

amino acid

Description

Amino acid found in green tea that promotes alpha brain waves, enhancing relaxation without drowsiness. Synergistic with caffeine for focus.

Safety & interactions

Very safe. No known serious side effects. Can be taken with caffeine for calm focus.
Check all interactions →

Protocols featuring L-Theanine

Sleep Optimization ProtocolSStrong Evidence
Cognitive Performance ProtocolAAdequate Evidence
Stress Resilience ProtocolAAdequate Evidence
Travel & Jet Lag RecoveryAAdequate Evidence
Evening Wind-Down ProtocolAAdequate Evidence
Focus & Productivity StackAAdequate Evidence

Studies on L-Theanine (8)

1.

Effects of L-Theanine Administration on Stress-Related Symptoms and Cognitive Functions in Healthy Adults: A Randomized Controlled Trial

Hidese S, et al. (2019) · Nutrients · n=30

RCTPubMedDOI
2.

L-Theanine reduces psychological and physiological stress responses

Kimura K, et al. (2007) · Biol Psychol · n=12

RCTPubMedDOI
3.

The effects of L-theanine consumption on sleep outcomes: A systematic review and meta-analysis.

Bulman A (2025) · Sleep medicine reviews · n=897

PubMedDOI
4.

Effects of Tea (Camellia sinensis) or its Bioactive Compounds l-Theanine or l-Theanine plus Caffeine on Cognition, Sleep, and Mood in Healthy Participants: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

Payne ER (2025) · Nutrition reviews

PubMedDOI
5.

Effects of chamomile and -theanine beverage on menstrual pain, menstrual symptoms, mood, and sleep quality in young women experiencing primary dysmenorrhea: A randomized, double-blind, placebo-controlled study.

Soh Z (2025) · Journal of food and drug analysis · n=15

PubMedDOI
6.

Minimal Influence of Formulated Nutritional Interventions on Sleep and Next-Morning Physical Performance, Cognitive Function, and Postural Sway in Adult Males: A Randomized, Placebo-Controlled, Crossover Study.

Morrison M (2025) · International journal of sport nutrition and exercise metabolism

PubMedDOI
7.

Performance-enhancing effects of caffeine and L-Theanine among Iranian elite wrestlers: a focus on cognitive and specific physical performance.

Razazan R (2025) · Journal of the International Society of Sports Nutrition

PubMedDOI
8.

High-dose L-theanine-caffeine combination improves neurobehavioural and neurophysiological measures of selective attention in acutely sleep-deprived young adults: a double-blind, placebo-controlled crossover study.

Nawarathna GS (2025) · The British journal of nutrition

PubMedDOI

Health domains

Cognitive performanceSleep & recoveryStress management

ProtocolEngine provides general health information based on published research. This is not medical advice. Consult a healthcare professional before starting any supplement or health protocol.