L-theanine is an amino acid predominantly found in the leaves of green tea. It is known for its mild calming effects without causing drowsiness.
L-theanine promotes relaxation, enhances concentration and cognitive functions, and reduces stress and anxiety levels.
Due to its influence on alpha brain waves and neurotransmitters such as serotonin and dopamine, L-theanine has become a popular supplement among those looking to enhance productivity and emotional wellbeing.
Health Benefits
- reduces stress and anxiety;
- increases concentration and attention without drowsiness;
- stimulates the production of dopamine and serotonin;
- improves sleep quality and promotes relaxation;
- may lower blood pressure and support cardiovascular health.
Daily Requirement and Sources
L-theanine is not an essential amino acid; however, its regular intake can be beneficial during psycho-emotional stress.
The recommended dose is between 100 to 400 mg per day.
Main sources:
- green and black tea – primary natural sources;
- supplements in the form of capsules or powders (commonly used in dosages of 200–400 mg);
- combinations with caffeine – to enhance concentration and mental clarity.
Possible forms and their learnability
Nutrient forms are listed from best to worst:
| Product | Price, $ |
|---|---|
Advance Physician Formulas, L-Theanine, 200 mg, 60 Capsules | 14.11 |
NaturesPlus, Pro L-Theanine 200, 200 mg, 60 Capsules | 7.39 |
NaturesPlus, Pro, Suntheanine L-Theanine 200, 100 mg, 60 Capsules | 14.30 |
Nutricost, L-Theanine, 200 mg, 240 Capsules | 19.31 |
Nutricost, L-Theanine, 200 mg, 120 Capsules | 8.71 |
NutraLife, L-Theanine, 200 mg, 60 Capsules | 11.30 |
NOW Foods, L-Theanine, 100 mg, 90 Veg Capsules | 14.88 |
NOW Foods, L-Theanine, Double Strength, 200 mg, 60 Veg Capsules | 17.59 |
NutraBio, L-Theanine, 200 mg, 90 Capsules | 23.01 |
Nature's Truth, Double Strength L-Theanine, 200 mg, 60 Quick Release Capsules | 10.21 |
Symptoms and Consequences of Deficiency
- increased anxiety and irritability;
- decreased concentration and mental performance;
- sleep issues (difficulty falling asleep, frequent awakenings);
- mental and emotional fatigue;
- elevated cortisol and stress levels.
Although a direct deficiency of L-theanine does not pose a life-threatening risk, its lack in the diet may reduce stress resilience and worsen cognitive state.
Possible Risks of Excess and Their Manifestations
- drowsiness and decreased concentration;
- muscle weakness and fatigue;
- headaches in sensitive individuals;
- d digestive disorders (heaviness, nausea);
- in rare cases – confusion or emotional instability.
A daily dose of up to 400 mg is considered safe. Exceeding this amount, especially in the form of supplements, may lead to side effects.