L-theanine is one of the compounds contributing to Gyokuro’s umami, alongside glutamic acid and citric acid, as a study of its umami components found. It is an amino acid found almost exclusively in Camellia sinensis, the tea plant, making up roughly 50% of all free amino acids in tea. In a small study, 50 mg of L-theanine increased alpha activity measured 45–105 minutes after ingestion; this does not establish a reliable effect from a cup of tea. Coffee has caffeine. Tea has caffeine and theanine — and that difference matters.
Shade-grown teas — Gyokuro and Matcha especially — can be rich in theanine, but measured amounts vary between teas. In a shading study, theanine in shaded shoots increased early and then gradually declined; shading does not guarantee continuous accumulation. Below is a quick reference for what theanine is and where it sits in the chemistry of tea.
| Property | Detail |
|---|---|
| Full name | L-theanine (gamma-glutamylethylamide) |
| Found in | Tea plants |
| Taste contribution | Umami, sweetness — the savory depth underneath the bitterness |
| Teas that can be rich in theanine | Gyokuro, Matcha, Kabusecha; amounts vary between teas |
| Interaction with caffeine | Small trials report differing results depending on dose and task; sustained focus or prevention of a caffeine spike or crash is not established |
| Discovery | Isolated from Gyokuro by Yajiro Sakato in 1949; first reported in 1950 |
What studies have examined about L-theanine
Alpha waves are measured using an electroencephalogram (EEG); a change in this activity alone does not establish improved concentration. Nobre et al. (2008, Asia Pacific Journal of Clinical Nutrition) reported increased alpha activity in a small study using 50 mg of L-theanine, measured 45–105 minutes after ingestion. For related literature, see Juneja et al. (1999, Trends in Food Science and Technology). The EEG findings do not establish a guaranteed calming effect without changes in attention.
Tea contains both caffeine and L-theanine, but the cited trials do not isolate why ordinary tea and coffee feel different. Caffeine sharpens attention by blocking adenosine receptors. Small trials of L-theanine with caffeine have reported differing results depending on dose and task. They do not establish sustained focus or prevention of a caffeine spike or crash. To understand how caffeine in tea works on its own terms, see the caffeine ingredient guide.
For a broader look at what tea does for the body, see our guide to green tea benefits.
Which teas have the most L-theanine
Gyokuro and Matcha can be rich in theanine, but amounts vary between teas and with preparation. In a shading study, theanine in shaded shoots increased early and then gradually declined; shading does not guarantee continuous accumulation. This is why covered cultivation produces teas with a sweeter, more umami profile alongside higher theanine content.
| Tea type | Relative theanine level | Why |
|---|---|---|
| Gyokuro | Often rich; varies | Shaded for about 20 days; composition varies with cultivation |
| Matcha | Can be rich; varies | Powdered leaf is consumed; theanine intake depends on powder content and amount used |
| Kabusecha | Varies | Shaded for about a week; theanine content varies with cultivation |
| High-grade Sencha | Moderate | Spring first-flush; theanine is transported from roots to growing shoots |
| Hojicha | Low | High-temperature roasting degrades theanine |
| Bancha | Low | Mature leaves; more catechins, less amino acid |
Spring teas also tend to have more theanine than summer or autumn harvests. In a winter-to-spring study, theanine accumulated in roots and was transported to growing shoots.
A short history of L-theanine research
L-theanine was first isolated from Gyokuro in 1949 by Yajiro Sakato and reported in 1950 in Nippon Nogeikagaku Kaishi. The literature includes Juneja et al. (1999); Nobre et al. (2008) reported increased alpha activity in a small study using 50 mg of L-theanine. EFSA’s 2011 assessment did not establish a cause-and-effect relationship for the cognitive, stress and sleep claims it evaluated. The honest framing is that theanine is one of the amino acids supporting the flavor and experience tea has carried for generations.
How brewing temperature shapes theanine extraction
Even a single tea can taste noticeably different depending on water temperature and steep time. Theanine can be extracted at 60–70°C; catechin extraction varies with temperature and catechin type. The practical effect is that a cooler, slower brew emphasizes umami and pulls back the astringency. Gyokuro is commonly brewed around 50°C for two minutes; lower temperatures can limit extraction of some catechins. Sencha brewed at around 70°C for 60 seconds gives a more balanced profile — umami still present, but carrying a cleaner, brighter edge of astringency.
The first infusion and second infusion also differ. In the tested Sencha, amino acids extracted readily in the first brew; the balance across later brews depends on temperature and time. When you want to enjoy multiple infusions from the same leaves, keep the first infusion cool and short to pull the sweetness, then raise the temperature slightly for the second to draw out the remaining flavor and aroma. The mechanism of shade cultivation and the chemistry of brewing point to the same conclusion: the way tea is grown and the way it is prepared are quiet decisions about how much theanine reaches your cup.
Tea delivers theanine alongside flavor, warmth, and the full spectrum of compounds that make the cup what it is. Gyokuro and Matcha can be rich in theanine, but amounts vary between teas and with preparation. Browse our tea leaves collection and see what the shaded fields taste like.
References
- Nobre et al., Asia Pacific Journal of Clinical Nutrition (2008) — paper on L-theanine in tea and its effect on mental state.
- Juneja et al., Trends in Food Science & Technology (1999) — article on L-theanine as a green tea amino acid and its relaxation-effect framing.
- Vuong et al., Journal of the Science of Food and Agriculture (2011) — review of L-theanine properties, synthesis, and isolation from tea.
- Sakato, Nippon Nogeikagaku Kaishi (1950) — original Japanese paper associated with the isolation and naming of L-theanine from Gyokuro.
- PubChem — L-theanine — compound entry from the U.S. National Library of Medicine.
The health-related information provided here is drawn from published research and is provided for educational purposes. It is not medical advice. If you have specific health concerns, please consult a qualified healthcare professional.
Frequently Asked Questions
How does L-theanine interact with caffeine?
Small trials of L-theanine with caffeine report differing results depending on dose and task. They do not establish sustained focus or prevention of a caffeine spike or crash. Nor do they isolate why ordinary tea and coffee feel different. To understand how caffeine in tea works on its own terms, see the caffeine ingredient guide.
How much L-theanine is in a cup of tea?
There is no fixed amount per cup: Gyokuro, Matcha, and Kabusecha can be rich in theanine, but amounts vary between teas; high-grade Sencha has moderate levels. How much reaches the cup also depends on water temperature and steep time. Tea delivers theanine alongside flavor, warmth, and the full spectrum of compounds that make the cup what it is.
Is L-theanine the same as theanine?
Yes. "L-theanine" is the precise chemical designation; "theanine" is the shorthand. Both refer to the same compound. Theanine is one of the amino acids supporting tea's flavor and experience. Gyokuro and Matcha can be rich in theanine, but amounts vary between teas and with preparation.
