---
type: Concept
title: L-Theanine
description: A calming amino acid nearly unique to the tea plant that pairs with caffeine
  to produce composed alertness rather than jitteriness.
tags:
- tea
- l-theanine
- chemistry
- health
resource: raw/tea-health-faq.md
timestamp: '2026-07-16T15:54:42Z'
citadel_version: 0.3.0
---

L-theanine is an amino acid that is nearly unique to the [tea](../objects/tea.md) plant, [Camellia sinensis](../objects/camellia-sinensis.md) — it is not found in most of the foods eaten day to day, which is part of what makes tea distinctive.[^s1] It dissolves into the cup as the leaf steeps, and it is responsible for much of the "settled" feeling drinkers describe after a good brew.[^s1] On its own, L-theanine nudges the body toward a calm, relaxed state.[^s2]

The more notable effect is what happens when L-theanine pairs with the [caffeine](caffeine.md) also present in the leaf: together they produce a calm, focused alertness rather than caffeine's sharper edge alone — sometimes described as "awake without the jitters" — giving tea a steadier, gentler lift than coffee's jolt.[^s3] This partnership, not any absence of caffeine, is why tea has a reputation for a composed kind of alertness: tea is not caffeine-free, it simply carries L-theanine alongside its caffeine.[^s4]

Shading is where that abundance comes from. Light normally converts L-theanine into catechins as the leaf grows; for roughly 20 to 30 days before harvest, bushes destined for gyokuro and for tencha (the leaf later stone-ground into [matcha](../objects/matcha.md)) are covered to block about 90% of the sunlight, halting that conversion so L-theanine accumulates in the leaf instead.[^s5] Because less L-theanine is being converted, [catechins](tea-antioxidants.md) — the astringent antioxidants — fall too, making shaded teas markedly less bitter; caffeine and chlorophyll rise instead, which is why shaded leaf turns a vivid jade green and keeps a solid caffeine punch despite tasting so soft.[^s6][^s7] Because L-theanine itself tastes sweet and brothy, the shaded cup reads as deep umami rather than grass — the reason gyokuro and good matcha taste sweet, marine, and savoury instead of vegetal.[^s8]

## See also
- [Caffeine](caffeine.md)
- [Tea](../objects/tea.md)
- [Tea Antioxidants](tea-antioxidants.md)
- [Camellia Sinensis](../objects/camellia-sinensis.md)
- [Matcha](../objects/matcha.md)

## Sources
[^s1]: [raw/tea-health-faq.md](../../raw/tea-health-faq.md), line 17 — L-theanine defined as an amino acid nearly unique to the tea plant, dissolving into the cup while steeping, behind the "settled" feeling (ingested 2026-07-16)
[^s2]: [raw/tea-health-faq.md](../../raw/tea-health-faq.md), line 21 — on its own, L-theanine nudges toward a calm, relaxed state (ingested 2026-07-16)
[^s3]: [raw/tea-health-faq.md](../../raw/tea-health-faq.md), line 25 — combined with caffeine, produces calm, focused alertness ("awake without the jitters"), steadier and gentler than coffee (ingested 2026-07-16)
[^s4]: [raw/tea-health-faq.md](../../raw/tea-health-faq.md), line 29 — tea's calm reputation comes from L-theanine alongside caffeine, not from being caffeine-free (ingested 2026-07-16)
[^s5]: [raw/tea-processing-and-cultivars.md](../../raw/tea-processing-and-cultivars.md), lines 105-114 — shading blocks ~90% of sunlight for 20-30 days before harvest, halting the light-driven conversion of L-theanine into catechins (ingested 2026-07-16)
[^s6]: [raw/tea-processing-and-cultivars.md](../../raw/tea-processing-and-cultivars.md), lines 115-117 — catechins fall under shading since less L-theanine converts into them (ingested 2026-07-16)
[^s7]: [raw/tea-processing-and-cultivars.md](../../raw/tea-processing-and-cultivars.md), lines 118-119 — caffeine and chlorophyll rise under shading (ingested 2026-07-16)
[^s8]: [raw/tea-processing-and-cultivars.md](../../raw/tea-processing-and-cultivars.md), lines 121-125 — shaded teas read as umami rather than vegetal; gyokuro and matcha (ingested 2026-07-16)
