Theanine plus caffeine improves cognitive and mood outcomes in healthy participants
This meta-analysis of 15 RCTs found small-to-moderate benefits of theanine plus caffeine over placebo on cognition and mood outcomes, including choice reaction time (SMD -0.48 at 1 hour) and digit vigilance task accuracy (SMD 0.20 at 2 hours). Theanine alone also showed a small-to-moderate benefit on choice reaction time (SMD -0.35 at 1 hour). However, confidence intervals were wide, indicating uncertainty in effect magnitude.
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Theanine plus caffeine improves cognitive and mood outcomes in healthy participants The current body of evidence comprises 1 study and 1 meta-analysis. EvidenceHub rates the overall confidence at 49/100 (low).
The Claim
Theanine plus caffeine improves cognitive and mood outcomes in healthy participants
This conclusion is most relevant to: Healthy participants (from 50 RCTs, 15 included in meta-analysis).
What the Research Shows
The conclusion draws on 1 linked study. Highlights from the cited literature:
- ▸Effects of Tea (Camellia sinensis) or its Bioactive Compounds l-Theanine or l-Theanine plus Caffeine on Cognition, Sleep, and Mood in Healthy Participants: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. (Nutrition reviews, 2025) —
How It Works
The proposed biological pathway:
- ▸Theanine and caffeine modulate neurotransmitter systems
- ▸Caffeine blocks adenosine receptors promoting alertness
- ▸Theanine increases alpha brain waves and reduces stress
- ▸Result: Improved cognitive performance and mood
Who Might Benefit
Evidence fit by population:
- ▸Healthy participants (from 50 RCTs, 15 included in meta-analysis)
Recommended Dose
Not specified in abstract
Limitations & Caveats
Important context when interpreting this evidence:
- ▸Confidence intervals were wide, highlighting uncertainty in direction and magnitude of effects
- ▸Only 15 of 50 included RCTs were eligible for meta-analysis, limiting generalizability
Frequently Asked Questions
Does theanine alone improve cognition?▼
Yes, theanine alone showed a small-to-moderate benefit on choice reaction time at 1 hour (SMD -0.35) compared to placebo.
What cognitive outcomes were improved by theanine plus caffeine?▼
Improvements were seen in choice reaction time, digit vigilance task accuracy, and attention switching task accuracy, particularly in the first two hours after intake.
Was the effect of theanine plus caffeine on mood significant?▼
There was a small-to-moderate difference favoring theanine plus caffeine on overall mood at 2 hours (SMD 0.26), but the confidence interval crossed zero, indicating uncertainty.
What population was studied in this meta-analysis?▼
The analysis included healthy participants from randomized controlled trials, though specific demographics (e.g., age, gender) were not detailed in the abstract.
References
- 1.Payne ER, Aceves-Martins M, Dubost J, Greyling A, de Roos B. “Effects of Tea (Camellia sinensis) or its Bioactive Compounds l-Theanine or l-Theanine plus Caffeine on Cognition, Sleep, and Mood in Healthy Participants: A Systematic Review and Meta-Analysis of Randomized Controlled Trials..” Nutrition reviews, 2025. PMID: 40314930 DOI: 10.1093/nutrit/nuaf054