How to get L-theanine naturally?: A comprehensive guide to dietary sources

October 4, 2025 •

2 min read

According to a review in Frontiers in Nutrition, the unique amino acid L-theanine is found almost exclusively in tea plants and certain fungi. Discover how to get L-theanine naturally by integrating specific dietary sources into your daily routine for their calming and cognitive benefits.

Quick Summary

L-theanine, an amino acid, is found in tea and certain mushrooms, offering benefits like relaxation and improved focus. Content varies based on the source and preparation.

Key Points

Tea is the richest natural source: L-theanine is found abundantly in tea leaves, especially green tea, matcha, white tea, and black tea.
Matcha offers a concentrated dose: As powdered, shade-grown green tea, matcha provides a higher, more concentrated intake of L-theanine compared to steeped teas.
Mushrooms are a secondary source: Certain mushrooms, such as the bay bolete, also contain L-theanine, though in smaller amounts than tea.
L-theanine promotes 'calm alertness': When combined with the caffeine naturally found in tea, L-theanine can enhance focus and concentration without causing jitters or anxiety.
Choose fresh, shade-grown leaves: The L-theanine content is higher in younger, early-harvest leaves and tea plants grown in the shade.
Herbal teas do not contain L-theanine: Herbal infusions like chamomile or peppermint are not true teas and therefore do not provide L-theanine.
Brewing methods impact content: The way you steep your tea affects the final L-theanine concentration in your cup; hotter water and longer steeping can extract more.

Understanding L-theanine: The Calming Amino Acid

L-theanine is an amino acid not produced by the human body, obtained through diet or supplements. It promotes relaxation without drowsiness by increasing alpha brain waves, associated with 'calm alertness'. L-theanine primarily comes from the tea plant (Camellia sinensis) and some mushrooms. It can cross the blood-brain barrier, affecting neurotransmitters that regulate mood, focus, and sleep. L-theanine also contributes to the 'umami' flavor in tea, balancing caffeine's bitterness.

Primary Natural Sources of L-theanine

Tea from the Camellia sinensis Plant

Tea is the most common natural source of L-theanine. Green, black, white, and oolong teas, all from the same plant, contain varying amounts depending on processing and growing conditions.

Green Tea: Known for high L-theanine, especially shade-grown varieties like Gyokuro and Kabusecha. Shading increases L-theanine levels.
Matcha: Powdered green tea made from shade-grown leaves provides a concentrated dose of L-theanine.
White Tea: Contains L-theanine, with higher levels in early spring harvests.
Black Tea: Has less L-theanine than green or white tea due to fermentation.
Herbal Teas: Do not contain L-theanine as they are not from the Camellia sinensis plant.

Mushrooms Containing L-theanine

Certain mushrooms contain L-theanine in smaller amounts than tea. The bay bolete (Boletus badius) is one such species.

How to Maximize L-theanine Intake Through Diet

Opt for high-quality matcha or shade-grown green teas, especially first flush harvests.
Adjust steeping time; hotter water and longer steeping can extract more L-theanine but also increase caffeine and bitterness. Cooler water and longer steep can extract more L-theanine while minimizing caffeine.
Start your day with matcha for focused energy.
Add bay bolete mushrooms to meals.
Maintain a daily tea routine.

Natural L-theanine vs. Supplements: A Comparison


Feature	Natural L-theanine (from Tea)	L-theanine Supplements
Source	Tea leaves (Camellia sinensis), certain mushrooms	Synthetically produced or naturally extracted
Dosage Control	Variable	Precise, standardized dosage
Co-existing Compounds	Contains caffeine, antioxidants, and other beneficial compounds	Isolated L-theanine
Jitters/Anxiety	Can counteract caffeine's stimulating effect	May cause side effects at high doses
Form	Liquid, powdered, solid	Capsules, tablets, or powders
Cost	Generally more cost-effective	Higher cost, especially for high-quality versions
Regulation	Regulated as a food product	Regulated as a dietary supplement; quality control varies

Key Benefits Associated with Natural L-theanine

Stress Reduction and Relaxation: Promotes alpha brain waves and may lower cortisol.
Improved Focus and Cognitive Performance: L-theanine and caffeine in tea can enhance cognitive function and attention.
Better Sleep Quality: Calming effects can aid sleep preparation.
Potential Immune Support: May support the immune system.
Support for Cardiovascular Health: May contribute to lower blood pressure by reducing stress.

Conclusion

Incorporating L-theanine into your diet through natural sources like tea, particularly matcha and shade-grown green teas, can promote relaxation, enhance focus, and support overall well-being. Certain mushrooms like the bay bolete offer a less concentrated alternative. Natural sources provide L-theanine alongside other beneficial compounds, offering a more holistic approach compared to isolated supplements. For additional information, the Cleveland Clinic is a reputable source.

Frequently Asked Questions

Matcha, a powdered green tea made from shade-grown leaves, contains the highest concentration of L-theanine because you consume the entire tea leaf instead of just the brewed infusion.

While tea and bay bolete mushrooms are the primary natural sources, some evidence suggests minimal amounts may also be found in certain plant-based foods like soybeans, though these are not considered significant dietary sources.

Yes, L-theanine is an amino acid distinct from caffeine, so decaffeinated versions of green, black, or white tea will still contain it, allowing for a relaxing, caffeine-free experience.

Shade-growing tea plants induces a stress response that boosts the production of L-theanine while slowing the conversion of amino acids into catechins, resulting in higher levels of L-theanine in the leaves.

L-theanine from natural tea sources is consumed with other beneficial compounds like caffeine and antioxidants, which create a balanced effect. Supplements offer a standardized, isolated dose, which may be more potent but lacks the full synergistic profile of the natural product.

The choice depends on your needs. For regular, moderate intake and a holistic profile, natural sources are ideal. For higher, controlled doses for specific therapeutic purposes, a supplement may be necessary, though more research on its effects is needed.

After consuming a tea or supplement, L-theanine is absorbed and reaches the brain within 30 to 60 minutes, with effects typically lasting several hours.