Theanine is an amino acid, but it is not one of the protein-building ones, and it is far less common in food than the amino acids covered in the leucine or phenylalanine guides. Wikipedia’s theanine entry describes it as found mainly in tea leaves from the Camellia sinensis plant, with some fungi also producing it, and notes that it makes up roughly 1% to 2% of the dry weight of green tea leaves. That makes tea the practical answer to “which foods are high in theanine.”
This guide ranks the tea types and food sources that have published numbers, then flags the ones that are known sources but have no reliable per-cup figure. A systematic review of L-theanine for stress and anxiety concluded that theanine may help people manage stress and anxiety, but the trials it reviewed used supplements at 200 to 400 mg per day, far more than a cup of tea delivers. See the section on tea versus supplements below. For related reading, see the guides to foods high in catechins and foods that help with anxiety.
Best Food and Drink Sources of Theanine, Ranked by Amount Per Serving
Jump to: Matcha | Black Tea | White Tea | Specialty Black Tea | Green Tea | Decaf Black Tea | Gyokuro | Mushrooms | FAQ
The first five entries have published theanine figures. Tea values come from a Food Chemistry study of theanine in a cup of tea that measured L-theanine in a standard 200 ml (about 7 fl oz) cup brewed for 2 minutes, and matcha values come from a Japanese analysis of matcha and powdered green tea. Caffeine figures come from The USDA FoodData Central database (SR Legacy), scaled to the same 200 ml cup. The last three entries are real sources, but the studies behind this guide did not give a per-cup number, so they are described and not ranked.
1. Matcha: The Highest Theanine Per Serving
In a Japanese analysis of matcha and powdered green tea, tea ceremony grade matcha contained more than 1.8 g of theanine per 100 g of dry weight, which is about 18 mg per gram. A 2 g serving (roughly one teaspoon of powder) would therefore supply up to about 36 mg, which is arithmetic from that figure, not a measured value. The same paper found that most industrial-grade matcha and powdered green tea samples had lower values, so a cheap culinary matcha will deliver less.
Matcha is the only tea here where you drink the whole leaf, ground into powder, so nothing is left behind in the strainer.
Best eaten: whisked with hot water, or stirred into milk or a smoothie.
| Nutrient | Amount |
|---|---|
| Serving | 2 g (about 1 tsp) matcha powder |
| Theanine | Up to about 36 mg (estimate) |
| Basis | Ceremonial grade, over 18 mg per g dry weight |
2. Black Tea: The Top Brewed Tea for Theanine
Regular black tea averaged 24.2 mg of theanine per 200 ml cup in the Food Chemistry study, with 9.1 mg per gram of dry leaf. That was the highest of any brewed tea in the study and about three times the green tea figure. The USDA lists brewed black tea at about 20 mg of caffeine per 100 g, so a 200 ml cup carries roughly 40 mg.
Black tea is also the cheapest and easiest option, since the standard supermarket tea bag falls in this category.
Best eaten: brewed for 4 to 5 minutes, plain or with a splash of milk.
| Nutrient | Amount |
|---|---|
| Serving | 200 ml (about 7 fl oz) cup, 2-minute brew |
| Theanine | 24.2 mg (plus or minus 5.7) |
| Per gram of dry leaf | 9.1 mg |
| Caffeine (USDA) | About 40 mg |
3. White Tea: A Mild Source
White tea averaged 11.5 mg of theanine per 200 ml cup, or 4.5 mg per gram of leaf, in the Food Chemistry study. Only two white tea samples were tested, so treat the figure as a rough guide and not a firm average.
It has a delicate flavor and works best with water that is hot but not boiling.
Best eaten: brewed lightly and served without milk.
| Nutrient | Amount |
|---|---|
| Serving | 200 ml cup, 2-minute brew |
| Theanine | 11.5 mg (plus or minus 2.1) |
| Per gram of dry leaf | 4.5 mg |
4. Specialty Black Tea: Lower Than Standard Black
The study also tested a category it labeled black specialty teas, which averaged 10.9 mg per 200 ml cup and 5.3 mg per gram. That is less than half the regular black tea figure, which shows how much theanine can vary within the same type of tea.
Specialty blends can differ a lot, and only five were tested.
Best eaten: plain, so you can taste the blend.
| Nutrient | Amount |
|---|---|
| Serving | 200 ml cup, 2-minute brew |
| Theanine | 10.9 mg (plus or minus 1.6) |
| Per gram of dry leaf | 5.3 mg |
5. Green Tea: Less Than Many People Expect
Green tea averaged 7.9 mg of theanine per 200 ml cup and 3.6 mg per gram in the Food Chemistry study, with wide variation between the three samples. The study reported that green tea released less theanine than black tea at every steeping time up to 30 minutes. Green tea is still worth drinking for its catechins, which the guide to foods high in catechins covers, but it is not the highest theanine option per cup.
The USDA lists brewed green tea at about 12 mg of caffeine per 100 g, or roughly 24 mg per 200 ml cup.
Best eaten: brewed with water below boiling and steeped for a few minutes.
| Nutrient | Amount |
|---|---|
| Serving | 200 ml cup, 2-minute brew |
| Theanine | 7.9 mg (plus or minus 3.8) |
| Per gram of dry leaf | 3.6 mg |
| Caffeine (USDA) | About 24 mg |
6. Decaf Black Tea: Theanine With Almost No Caffeine
The Food Chemistry study tested one decaffeinated black tea and found it contained significantly more theanine than the regular version of the same brand. One product is too few to generalize, and the exact figure appears only in the paper’s chart, so no number is given here. The USDA lists brewed decaffeinated black tea at about 1 mg of caffeine per 100 g, or roughly 2 mg per 200 ml cup.
If caffeine makes you jittery, decaf is the simplest way to keep tea in the evening routine.
Best eaten: brewed as you would regular black tea.
7. Gyokuro and Other Shade-Grown Teas: Higher Theanine by Design
Shading the tea plants before harvest raises theanine, and Wikipedia’s entry lists matcha and gyokuro as examples. A study of gyokuro-style tea grown in Australia found that shading tea plants for several weeks raised the ratio of theanine to caffeine, and it links theanine to the strong savory (umami) taste of gyokuro. The paper reports ratios and not absolute amounts, so there is no reliable per-cup number to rank gyokuro against the teas above.
Gyokuro is a Japanese green tea that costs more than everyday tea, and it is usually brewed in small amounts at a low temperature.
Best eaten: brewed in a small pot with water around 60 to 70 degrees Celsius for a short steep.
8. Mushrooms: Present, but Not Quantified
Wikipedia says some fungi produce theanine and cites the bay bolete (Xerocomus badius) as an example. The FooDB entry for theanine also lists common mushrooms, oyster mushrooms, and mushrooms in general as sources, but gives no concentrations for them. Because there is no per-serving data, mushrooms should be treated as a minor, unmeasured source and not a way to reach a target.
Best eaten: sauteed, roasted, or added to soups, for their other nutrients.
Quick Reference: Theanine in Tea Types at a Glance
| Food | Serving | Theanine |
|---|---|---|
| Matcha, ceremonial grade | 2 g powder | Up to about 36 mg (estimate) |
| Black tea | 200 ml, 2-minute brew | 24.2 mg |
| White tea | 200 ml, 2-minute brew | 11.5 mg |
| Specialty black tea | 200 ml, 2-minute brew | 10.9 mg |
| Green tea | 200 ml, 2-minute brew | 7.9 mg |
| Decaf black tea | 200 ml, 2-minute brew | Higher than regular (no number given) |
| Gyokuro | Small pot | No per-cup figure |
| Mushrooms | Per serving | Not quantified |
How Much Theanine Do You Get From Tea Compared With Supplements?
The trials in a systematic review of L-theanine for stress and anxiety used 200 to 400 mg of L-theanine per day from supplements. Using the cup figures above, 200 mg would take about 8 cups of regular black tea (around 330 mg of caffeine) or about 25 cups of green tea. Those are calculations from the figures above, not measured values, and they show that normal tea drinking sits well below the amounts used in research.
The evidence for supplements is also still developing. The Examine theanine page says the most likely effects are less anxiety and stress, with sleep and focus benefits less certain and needing more research. Wikipedia’s theanine entry reports that the European Food Safety Authority found insufficient evidence for health claims in 2011, and that the U.S. FDA considers theanine generally recognized as safe in foods and beverages up to 250 mg per serving. If you are thinking about a supplement, talk to a doctor or pharmacist first.
5 Practical Tips for Getting Theanine From Tea
- Steep longer. The Food Chemistry study found theanine extraction rose quickly during the first 5 minutes and kept climbing slightly afterward, so the 2-minute figures above are on the low side for a cup you steep for 4 to 5 minutes.
- Choose black tea over green if theanine is the goal. Regular black tea delivered about three times the theanine of green tea per cup in the study. Keep green tea in the mix for its catechins, which are covered in the guide to foods high in catechins.
- Buy matcha by grade. The matcha analysis found ceremonial grade had the most theanine and industrial grades had less, so a bargain powder may not deliver what the label implies.
- Do not count on herbal teas. The Food Chemistry study notes that rooibos (redbush) tea contains no theanine because it does not come from the Camellia sinensis plant.
- Look at the whole picture for stress and focus. Sleep, caffeine, and meals matter alongside any single compound. The guides to foods that lower cortisol and foods that boost focus and concentration cover the food side, and the guide to foods that boost dopamine covers mood.
Frequently Asked Questions About Theanine in Food
What foods are highest in theanine?
Tea is the main dietary source. Among the teas with published numbers, ceremonial grade matcha is highest per serving, followed by regular black tea, white tea, specialty black tea, and green tea. Some mushrooms also contain it, but no per-serving figures are available.
Does green tea have more theanine than black tea?
Not per cup in the data used here. Regular black tea averaged 24.2 mg per 200 ml cup and green tea 7.9 mg in the same study. Shade-grown green teas such as matcha and gyokuro are a different case and tend to be richer in theanine.
Does coffee contain theanine?
Coffee is not listed among its dietary sources. Theanine comes from tea leaves and a few fungi.
How much theanine do you need per day?
There is no official daily requirement. Trials of supplements have used 200 to 400 mg per day, and the EFSA found insufficient evidence for health claims. A cup of tea supplies roughly 8 to 24 mg, depending on the type.
Does decaf tea still have theanine?
Yes. The one decaffeinated black tea tested contained more theanine than its regular version, though one sample is not enough to say that all decaf teas do.
The Bottom Line
Theanine is concentrated in tea, so the practical way to get it from food is to drink tea. Ceremonial grade matcha and regular black tea lead the numbers, while green tea is lower per cup than many people assume. A cup of tea supplies a fraction of the 200 to 400 mg used in supplement trials, so tea is best seen as a pleasant everyday habit and not a replacement for a supplement. Steep for longer, pick your tea by grade, and keep an eye on caffeine.
Theanine values are from published studies (a Food Chemistry paper for brewed teas at a 2-minute steep, and a Japanese analysis for matcha), and caffeine values are from the USDA FoodData Central database (SR Legacy), scaled to a 200 ml cup. Actual values vary by tea, leaf grade, water temperature, and steeping time.
This article is for educational purposes and is not a substitute for advice from a registered dietitian or physician. Talk to a healthcare professional before taking theanine supplements or changing your caffeine intake, especially if you are pregnant, take medication, or have a medical condition.
