Evidence guide · Theanine

L theanine and matcha.

The amino acid behind matcha's sweet, brothy taste, and the reason people say matcha feels calmer than coffee. What the human trials found, and what they cannot tell you.

AArabella L.Evidence guides, TeafyPublished 11 November 20265 min read

A bowl of vivid green matcha on a light wooden table with a few fresh tea leaves beside it

The short answer

L theanine is an amino acid found almost only in tea, and shading tea before harvest increases it, which is why matcha and gyokuro are rich in it. Small human trials suggest theanine taken with caffeine may modestly help attention, and one trial found 200 mg a day of theanine improved self reported sleep. Trial doses are usually higher than a bowl of matcha provides, and matcha still contains real caffeine.

In this guide
  1. What L theanine is
  2. What the human trials found
  3. Matcha, coffee and a capsule
  4. Matcha and sleep
  5. How much theanine is in matcha?
  6. Questions people ask
  7. Sources

What L theanine is

Theanine is an amino acid that tea plants make in their roots and send to the young leaves. It tastes sweet and brothy, and it is a big part of matcha's umami.

Why shaded tea is richer in theanine
RootsThe plant makes theanine and sends it up to new shoots.
Young leafTheanine collects in the tender top leaves.
SunlightLight turns theanine into catechins, which taste bitter.
ShadeCovering the bushes for two to three weeks slows that change.
Matcha, gyokuroShaded teas keep more theanine than sun grown sencha.

What the human trials found

Study
What was given
What they found
Limits
Camfield and colleagues, Nutrition Reviews, 2014, systematic review
Theanine with caffeine, single doses
Combined, they improved alertness and accuracy when switching attention between tasks
Small, short studies; doses above a typical bowl
Hidese and colleagues, Nutrients, 2019, randomised trial
200 mg theanine a day for 4 weeks
Better self reported sleep and stress scores in healthy adults
Small trial; capsules, not tea
Matsumoto and colleagues, 2011, randomised trial, Japan
Capsules of 210 mg theanine plus 378 mg catechins a day
Fewer influenza cases in healthcare workers than placebo
Capsules; a single trial
How strong is the evidence?

How strong the evidence is, graded by us from the study types: 5 is strong, 1 is very limited.

Theanine plus caffeine helps attention, short term
Theanine improves self reported sleep
Theanine reduces stress
A bowl of matcha does any of these

The honest summary: theanine is interesting and the early human research is encouraging. But the studies are small, they mostly use supplements, and the doses are usually higher than you get from a bowl or two of matcha.

Matcha, coffee and a capsule

2 g matcha
250 ml brewed coffee
Theanine capsule
Caffeine
About 64 mg
About 80 mg
None, unless added
Theanine
Some; varies with harvest and shade
None
Usually 100 to 200 mg
Studied for focus
Not directly
Caffeine alone, widely
In small trials, often with caffeine

Less caffeine per serve, plus theanine, is a plausible reason many people feel matcha is smoother than coffee. It is not proven that matcha releases caffeine more slowly, so we do not claim it.

Matcha and sleep

The sleep trial used theanine supplements, not tea. Matcha contains caffeine, and caffeine's average half life is about 4 hours (EFSA), so an afternoon bowl can still be with you at bedtime.

  1. Want a warm evening cup? Hojicha or genmaicha, both much lower in caffeine.
  2. Love matcha after lunch? Try 1 g instead of 2 g.
  3. Check your day with the caffeine planner in our matcha caffeine guide.

How much theanine is in matcha?

It varies with harvest, shading, cultivar and grade, so any single number would be a guess. What is consistent: first flush, well shaded leaf carries more theanine than later, sunnier harvests. That is also why it tastes sweeter.

Australian searches for matcha focus and theanine

Monthly Google searches in Australia.

OctNovDecJanFebMarAprMayJunJulAugSep
l theanine matcha · about 210 at peak

Peak month for l theanine matcha: Jun. Quietest: Dec.

Google Ads Keyword Planner, Australia, all languages, Google Search. Monthly figures are Google estimates, rounded into ranges.

Questions people ask

Does matcha contain L theanine?
Yes. Shading tea before harvest increases theanine, so matcha and gyokuro are richer in it than sun grown green teas.
Does L theanine help you focus?
Small studies suggest theanine taken with caffeine may modestly improve attention. The evidence is early and mostly uses supplement doses.
Is matcha good for focus?
Matcha contains caffeine and some theanine, a combination studied for attention in small trials, but matcha itself has not been well tested for focus.
Is matcha good before bed?
Not usually. A 2 g matcha has about 64 mg of caffeine. Hojicha or genmaicha are gentler evening choices.
How much theanine is in matcha?
It varies with harvest, shading and grade. Trial doses of 100 to 200 mg are usually more than a typical bowl provides.
Can I take L theanine with coffee?
Some trials gave theanine with caffeine. Whether it suits you is a question for your GP or pharmacist, especially if you take medicines.
A

Arabella L.

Evidence guides, Teafy

Arabella writes the Teafy evidence guides. She reads the trials and the official tables, grades how strong the evidence is, and says plainly what it does and does not show.

Sources

  1. Camfield DA, Stough C, Farrimond J, Scholey AB. Acute effects of tea constituents L theanine, caffeine, and epigallocatechin gallate on cognitive function and mood: a systematic review and meta analysis. Nutrition Reviews 2014;72(8):507 to 522
  2. Hidese S and colleagues. Effects of L theanine administration on stress related symptoms and cognitive functions in healthy adults: a randomized controlled trial. Nutrients 2019;11(10):2362
  3. Matsumoto K and colleagues. BMC Complementary and Alternative Medicine 2011;11:15, PMC3049752
  4. EFSA, Caffeine explained, and Scientific Opinion on the safety of caffeine, EFSA Journal 2015;13(5):4102
  5. MEXT Food Composition Database, matcha (16035): caffeine 3.2 g and tannin 10.0 g per 100 g
  6. Google Ads Keyword Planner, Australia, searches October 2025 to September 2026, checked 11 November 2026

We update this page when the numbers change, and date every change here.

Teas in this guide

Ceremonial Grade MatchaFrom our family farm in Shizuoka. Stone milled, first flush, 25 bowls a pouch.From $31.99Hojicha PowderRoasted to our own recipe in Shizuoka. Low caffeine, warm and nutty.From $25.99Kyoto Uji Ceremonial Matcha, OkumidoriSingle cultivar Okumidori from Uji. Stone milled, for whisking straight.From $54.95

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