Nutrition Diet: What foods are high in L-theanine?

October 4, 2025 •

4 min read

Discovered in 1949, L-theanine is a unique, non-protein amino acid primarily found in the leaves of the tea plant and certain mushrooms. It is celebrated for its ability to foster a state of relaxed alertness and mental clarity, often without inducing drowsiness. For those seeking to enhance their cognitive function and promote relaxation naturally, understanding what foods are high in L-theanine? is a crucial first step toward optimizing your diet.

Quick Summary

L-theanine is an amino acid found predominantly in teas from the Camellia sinensis plant, including green tea and matcha, which is the most concentrated source. Smaller amounts are also present in specific types of mushrooms, such as the bay bolete.

Key Points

Tea is the main source: L-theanine is found primarily in tea leaves from the Camellia sinensis plant, including green, matcha, white, and black teas.
Matcha offers the most: Ceremonial grade, shade-grown matcha is the most concentrated food source of L-theanine, as it involves consuming the entire ground tea leaf.
Mushrooms contain small amounts: The bay bolete mushroom (Boletus badius) is one of the only non-tea food sources, though its L-theanine content is significantly lower.
Processing affects content: The level of oxidation in tea leaves impacts L-theanine content, which is why minimally processed green and white teas often have more than fully oxidized black tea.
Natural vs. supplemental intake: Natural food sources provide variable L-theanine amounts, while supplements offer a higher, more standardized dose for targeted effects.
Enhances focus and relaxation: The L-theanine in tea promotes a state of calm alertness, especially when paired with the caffeine also present in the beverage.

The Primary Dietary Sources of L-theanine

While L-theanine is available in supplement form, incorporating it directly from natural dietary sources is an effective strategy for many people. The primary sources of this calming amino acid are derived from the Camellia sinensis plant, but a select few mushroom species also contain it.

Tea leaves from the Camellia sinensis plant

All true teas—green, black, white, and oolong—come from the same plant, but their L-theanine content varies significantly based on processing and growing conditions.

Matcha: As a powdered green tea, matcha is typically the richest food source of L-theanine. This is because it is made from shade-grown leaves, a process that boosts the leaves' amino acid content, and when consumed, you ingest the entire leaf rather than just the infusion. Ceremonial grade matcha is often cited as having the highest concentration.
Green Tea: Standard green tea contains a healthy dose of L-theanine, which provides the unique savory, umami flavor. Factors such as the specific cultivar, season of harvest, and amount of steeping time can all influence the final L-theanine content in your cup.
White Tea: This minimally processed tea, made from young leaves and buds, also contains L-theanine. Due to its delicate processing, it retains a good amount of the natural compounds, though it often has a slightly lower concentration than green tea.
Black Tea: The fermentation or oxidation process used to produce black tea reduces its L-theanine content compared to green and white teas. However, some studies have found surprising variability, with some lower-quality black tea bags showing higher amounts due to factors like brewing methods.
Oolong Tea: Oolong is a partially oxidized tea, meaning its L-theanine content typically falls somewhere between green and black tea.

Mushrooms with L-theanine

Outside of the tea family, the natural sources of L-theanine are very limited. One notable exception is a particular species of edible mushroom.

Bay bolete (Boletus badius or Xerocomus badius): This mushroom is one of the only other non-synthetic sources of L-theanine. While its content is not as high as in tea, incorporating bay bolete into cooking can offer a small, natural boost of the amino acid alongside its earthy flavor.

Natural Sources vs. Supplements

For those wondering how to maximize their intake, it's important to consider the difference between consuming L-theanine through food and using supplements. Food sources provide a natural, holistic approach, but dosage can be inconsistent. A cup of green tea can offer anywhere from 8 to 30 mg of L-theanine, depending on preparation. In contrast, supplements offer a standardized, higher dosage, with many clinical studies using 200 mg or more per day to observe significant effects on stress and anxiety. The decision to use supplements over food sources often depends on individual health goals and the desired level of effect. The combination of L-theanine and caffeine naturally found in tea is well-regarded for its synergistic effect in promoting calm focus.

Maximizing Your L-theanine Intake

To increase your L-theanine consumption through diet, you can follow these simple tips:

Brewing Technique: Use a shorter steeping time for green and white teas to minimize the release of bitter-tasting compounds like catechins, which can mask the sweet umami flavor of L-theanine.
Start with Matcha: Since matcha provides the highest and most concentrated amount of L-theanine per serving, it's an excellent way to get a significant dose. Try adding it to smoothies, lattes, or baked goods.
Experiment with Blends: Consider blending different types of tea or infusing L-theanine-rich teas with other complementary flavors.
Incorporate Mushrooms: Use bay bolete mushrooms in savory dishes like soups, stews, and risotto to add both flavor and a touch of L-theanine.

Comparison of L-theanine Content in Teas


Tea Type	L-theanine Content (Approx. per gram of dry leaves)	Notes
Matcha (Shade-grown)	6–20 mg/g	Highest concentration; involves consuming the entire leaf.
Green Tea (General)	~6.56 mg/g	Varies by cultivar, harvest, and brewing method.
White Tea	~6.26 mg/g	Minimally processed; good source but generally lower than green.
Oolong Tea	~6.09 mg/g	Partial oxidation; medium content.
Black Tea	~5.13 mg/g	Fully oxidized; lowest content among true teas.

Note: L-theanine content can vary widely depending on the specific product, growing conditions, and preparation.

Conclusion: Finding Your Calm in Food

For anyone looking to incorporate L-theanine into their diet, the path starts with tea, and specifically matcha, for the most concentrated dose. While some wild mushrooms offer a very minor amount, the vast majority of dietary L-theanine comes from the Camellia sinensis plant. By experimenting with different teas and brewing techniques, you can naturally increase your intake of this unique amino acid to support relaxation and mental focus. As with any dietary strategy, consistency and mindful preparation are key to reaping the benefits of L-theanine-rich foods.

For more in-depth scientific information on the effects and sources of L-theanine, you can consult research articles on reputable sites such as the National Institutes of Health (NIH).

Frequently Asked Questions

Yes, green tea generally has a higher L-theanine content than black tea because black tea undergoes a fermentation process that reduces the amino acid's concentration.

Matcha is widely considered the best food source because it is made from shade-grown tea leaves and consumed as a whole powder, providing a more concentrated amount of L-theanine than brewed tea.

No, true L-theanine comes only from the Camellia sinensis tea plant and certain mushrooms. Herbal teas, such as chamomile or peppermint, are not made from this plant and do not contain L-theanine.

In tea, L-theanine and caffeine work synergistically. The L-theanine promotes relaxation and mental clarity, which can help to counteract the jittery side effects that some people experience from caffeine.

No, L-theanine is found in only a few specific mushroom species, most notably the bay bolete (Boletus badius). It is not present in most commonly consumed mushrooms.

For most green teas, steeping for a shorter time in slightly cooler water can help preserve the L-theanine and produce a sweeter, more savory taste, as longer steeping can release more bitter-tasting compounds.

While food sources like tea can help promote relaxation, the amount of L-theanine is much lower and more variable than in supplements. Clinical studies for anxiety relief often use higher, standardized doses found in supplements, so food may not provide the same therapeutic effect.