The effects of L-theanine, caffeine and their combination on cognition and mood
Haskell CF
Published in Biological Psychology
Methodology
Randomised, placebo-controlled, double-blind balanced crossover trial testing L-theanine (250 mg), caffeine (50 mg), their combination and placebo on cognitive tasks and mood measures at 60 and 90 minutes.
Key Findings
In healthy young adults, 50 mg caffeine improved accuracy on attention-switching tasks and reduced susceptibility to distraction, while 250 mg L-theanine alone slowed simple reaction time; the combination improved attention-switching accuracy and reduced distractibility more than caffeine alone, and caffeine increased alertness ratings.
Conclusions
L-theanine combined with caffeine improves focused attention beyond caffeine alone in healthy adults, supporting the popular pairing for cognitive performance, though effects are acute and modest.
Limitations
Small crossover sample of healthy young adults, single-dose acute testing only, no data on repeated use or tolerance, and habitual caffeine intake may modify responses.
Supplements Studied
These results suggest that beverages containing L-theanine and caffeine may have a different pharmacological profile to those containing caffeine alone.
Related Health Concerns
Study Details
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Disclosures
Funding
Industry-supported (tea/amino acid supplier) with academic conduct
This information is for educational purposes only. Always consult a healthcare professional before starting any supplement regimen.