OYAH INGREDIENT LIBRARY

L-theanine

L-theanine is a non-protein amino acid found in tea. Many attention studies test it together with caffeine, so combination findings should not be assigned to L-theanine alone.

Evidence reviewUpdated 11 October 2026
LCalm attention / tea amino acid
Evidence signalSmall acute effects; combination evidence is stronger
Research focusAttention, task switching, mood and perceived stress
Key qualifierL-theanine alone versus L-theanine plus caffeine

What it is

L-theanine occurs naturally in tea leaves. Supplement studies usually examine an isolated amount of L-theanine, either alone or paired with caffeine. These are different interventions with different expected effects.

What human research suggests

Reviews report small improvements in selected attention or mood outcomes, especially during the first hours after L-theanine and caffeine are taken together. Results are inconsistent across tests, and recent reviews describe the cognition evidence as promising but inconclusive. This does not establish treatment for anxiety or a reliable improvement in daily productivity.

HOW THIS RELATES TO OYAH

L-theanine in an OYAH formula.

The related product page shows the current ingredient list and directions. Compare those details with each paper before deciding how closely the evidence applies. OYAH does not claim that the finished formula was tested in the linked studies.

Cognitive PerformanceView Cognitive Performance
Ingredient studyTests a defined ingredient, preparation and protocol.Finished-product evidenceWould require a clinical trial of the complete formula.Certificate of AnalysisReports the tests shown for a sample or lot; it does not establish benefit.
SAFETY & CONTEXT

What to consider before use.

L-theanine appears well tolerated in short human trials, but long-term and pregnancy data remain limited. Products containing caffeine carry separate considerations, including sleep disruption, anxiety, palpitations and sensitivity during pregnancy. People using blood-pressure medicine or sedatives should ask a healthcare professional about possible additive effects.

This guide is educational and is not medical advice. Speak with a qualified healthcare professional about pregnancy, breastfeeding, medical conditions, medicines, surgery or persistent symptoms.

READ THE SOURCES

Follow the evidence.

Each link opens the publication, indexed record or government guidance. Study findings remain limited to the preparation and protocol researchers examined.

  1. Tea compounds, cognition, sleep and mood2025 systematic review and meta-analysis of randomized trials · PMID 40314930 ↗
  2. L-theanine and cognitive performance2025 systematic review and meta-analysis · PMID 41227106 ↗
  3. Acute effects of tea constituents2014 systematic review and meta-analysis · PMID 24946991 ↗
  4. L-theanine with caffeine in cognitive tasks2008 randomized crossover trial · PMID 18681988 ↗
Current product directory

Know the product. Read the evidence.

Compare the current OYAH range, then open the product-specific evidence and ingredient guides. Ingredient studies do not establish the benefits of a finished OYAH formula.