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For informational purposes only. Always consult a qualified medical professional before taking any supplement, herb, vitamin, mineral, or bioactive, especially if you use medications or have a medical condition. Read the full disclaimer.
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PromisingReviewed

Amino Acids

L-Theanine

Protein building blocks and amino-acid-derived compounds used in muscle, neurotransmitter, nitric oxide, and connective tissue pathways.

Page last reviewed: 2026-07-23 - next review due: 2027-01-23

Source Coverage

Included: US reference
Review gap: Canadian reference
Add or verify Health Canada context where an official Canadian reference exists.
Review gap: EU reference
Add or verify EFSA or EU health-claim context where an official EU reference exists.
Included: Clinical / safety source

Function

Tea amino acid associated with relaxed alertness and modulation of excitatory neurotransmitter signaling.

Natural Sources

Green tea, black tea, white tea, matcha, some mushrooms.

Food vs Supplement Context

Natural sources describe where this item appears in foods, culinary ingredients, or traditional preparations. Concentrated supplements can differ by dose, extract type, preparation, standardization, and medication context, so they should be evaluated separately.

Testing & Monitoring Context

  • No routine lab test establishes a required daily need for most foods and bioactives; monitoring is usually based on the intended outcome, dose, medical history, and adverse effects.

Suggested Guidelines When Purchasing

What to look for: Prefer a product identity that matches the studied ingredient or ordinary food source described on this page.

Use caution or avoid: Avoid products that hide dose, source, standardization, allergens, or safety-relevant ingredients.

  • Prefer ordinary food sources first when they provide the intended compound in a practical way.
  • For supplements, require clear labeling of active ingredient, dose per serving, serving size, and other ingredients.
  • Prefer products with third-party testing or transparent contaminant testing, especially for concentrated extracts, algae, mushrooms, minerals, and sports products.
  • Do not let marketing claims override the evidence, safety flags, source coverage, or dose context on this page.

Intake Guidance

No official DRI

No official RDA, AI, or RDI has been established for this bioactive as a required daily intake.

Evidence Summary

Evidence Legend

Established use: Supported by official guidance, regulatory claim context, strong consensus, or repeated human evidence for a specific use.
Promising: Human studies or reviews suggest benefit for specific outcomes, but evidence is not broad enough to treat as settled general guidance.
Emerging: Early human, mechanistic, or mixed evidence; worth tracking, but not strong enough for confident user-facing claims.
Traditional use: Historically or traditionally used, but modern clinical evidence may be limited, mixed, or product-specific.
Category example: Included to describe a supplement or food category, not because a strong health claim is attached yet.

Sources

FoodData Central

U.S. Department of Agriculture - acquired 2026-07-23 - Food Database