Nootropic profile
L-Theanine
An amino acid found naturally in tea leaves, L-Theanine promotes relaxation without drowsiness. It is widely used for reducing anxiety, improving focus, and enhancing sleep quality - often stacked with caffeine for calm, sustained attention.
Best for
Educational only: this is not medical advice. Always check with a qualified healthcare professional before starting any supplement.
What is L-Theanine?
L-Theanine (γ-glutamylethylamide) is a non-protein amino acid found primarily in tea leaves (Camellia sinensis) and certain mushrooms. It is one of the most well-studied and widely used nootropics, prized for its ability to promote a state of calm focus without causing sedation.
What it does for you
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How to take it
- Typical dose: 100–200 mg per day
- With caffeine: A common stack is 100 mg L-Theanine with 50 mg caffeine (2:1 ratio) for calm, focused energy
- For sleep: 200–400 mg taken 30–60 minutes before bed
- For anxiety: 200 mg as needed, up to 2–3 times per day
- Upper limit: Generally considered safe up to 400 mg per day, though some studies have used higher doses without adverse effects
Watch out for
- Side effects: Very few reported side effects. Occasional reports of headache or dizziness at high doses.
- Drug interactions: May enhance the effects of blood pressure medications. Consult a doctor if taking antihypertensives.
- Pregnancy: Insufficient data - consult a healthcare provider before use during pregnancy or breastfeeding.
- Generally Recognised as Safe (GRAS): L-Theanine has GRAS status from the FDA for use in food and beverages.
The science, if you're curious.
- L-Theanine increases levels of GABA (gamma-aminobutyric acid), the brain's primary inhibitory neurotransmitter, promoting relaxation and reducing neural...
- It stimulates alpha brain wave activity, which is associated with a relaxed but alert mental state - similar to meditation.
- L-Theanine modulates glutamate receptors, helping to prevent excitotoxicity and supporting healthy neural signalling.
- It increases levels of dopamine and serotonin in certain brain regions, contributing to improved mood and motivation.
Where to find it
- Green tea: The most common natural source, containing approximately 25–60 mg per cup
- Black tea: Contains slightly less L-Theanine than green tea
- White tea: Contains moderate amounts of L-Theanine
- Bay bolete mushrooms: (Imleria badia) - a less common natural source
- Supplements: Available as capsules, tablets, and powder. Look for products labelled "Suntheanine" for a patented, high-purity form.
The research
L-theanine, a natural constituent in tea, and its effect on mental state
Nobre AC, Rao A, Owen GN - Asia Pacific Journal of Clinical Nutrition
L-theanine promotes relaxation and improves attention when combined with caffeine, without causing drowsiness.
L-Theanine reduces psychological and physiological stress responses
Kimura K, Ozeki M, Juneja LR, Ohira H - Biological Psychology
L-theanine (200mg) significantly reduced psychological and physiological stress responses without causing sedation.
Improved cognitive performance in human volunteers following administration of guarana (Paullinia cupana) extract: comparison and interaction with Panax ginseng
Kennedy DO, Haskell CF, Wesnes KA, Scholey AB - Pharmacology Biochemistry and Behavior
Caffeine significantly improved attention, speed, and accuracy, with enhanced effects when combined with theanine.
Frequently asked
An amino acid found naturally in tea leaves, L-Theanine promotes relaxation without drowsiness. It is widely used for reducing anxiety, improving focus, and enhancing sleep quality - often stacked with caffeine for calm, sustained attention.
The main benefits people report from L-Theanine are: Anxiety & Calm, Cognitive Enhancement, Energy, Focus, Mood, Sleep.
Typical dose: 100–200 mg per dayWith caffeine: A common stack is 100 mg L-Theanine with 50 mg caffeine (2:1 ratio) for calm, focused energyFor sleep: 200–400 mg taken 30–60 minutes before bedFor anxiety: 200 mg as needed, up to 2–3 times per dayUpper limit: Generally considered safe up to 400 mg per...
Side effects: Very few reported side effects. Occasional reports of headache or dizziness at high doses.Drug interactions: May enhance the effects of blood pressure medications. Consult a doctor if taking antihypertensives.Pregnancy: Insufficient data - consult a healthcare provider before use durin...
L-Theanine increases levels of GABA (gamma-aminobutyric acid), the brain's primary inhibitory neurotransmitter, promoting relaxation and reducing neural...It stimulates alpha brain wave activity, which is associated with a relaxed but alert mental state - similar to meditation.L-Theanine modula...
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