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L-Theanine

Evidence: ★★★★☆ · Status: OTC Supplement

💡 Did you know? L-theanine, the calming compound in green tea, smooths out caffeine's jitter — which is why a matcha feels so different from a coffee.

In plain English

It's the "calm" molecule in green tea. Paired with caffeine, it removes the jitter and gives you smooth focus instead of a wired buzz.

How it works

Amino acid from tea that crosses the blood-brain barrier and increases GABA, glycine, and alpha-wave EEG activity while modulating glutamate (NMDA/AMPA) tone. Blunts the sympathetic overshoot of caffeine without reducing its focus benefit.

Molecular target & official sources

GABRA1 GABA-A receptor subunit (NCBI Gene) · L-Theanine (PubChem CID 439378)

Protocol

200 mg theanine : 100 mg caffeine for focus; 200–400 mg alone for sleep.

Bottom line

The most practical no-prescription focus stack.

Helps with: Sleep Better · Focus & Cognition · Stress & Anxiety

Stacks with

Caffeine — the classic calm-focus pairing (roughly 1:2 caffeine:theanine); removes the jitters without dulling the alertness.

Shares a pathway — often paired with: Magnesium, N-Acetylcysteine (NAC), Phentermine / Qsymia (phentermine-topiramate), Ashwagandha (Withania somnifera).

Availability & where to buy

Available over the counter. Widely available OTC — e.g. iHerb (ships worldwide); in Singapore also Guardian, Watsons, GNC, Shopee / Lazada. Look for a third-party-tested / GMP mark and check the dose per serving. Cheap — ~S$15–25/month. iHerb, Guardian, Shopee.

How it works: the GABA / Glutamate pathway →

Used in these protocols

Compare L-Theanine

Common questions

Does L-Theanine actually work?

Human-evidence rating: 4 of 5. The most practical no-prescription focus stack.

How do you take L-Theanine?

200 mg theanine : 100 mg caffeine for focus; 200–400 mg alone for sleep.

Is L-Theanine legal or approved?

Regulatory status: OTC Supplement.