SynthesisNutrition reviews2025
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.
Synthesis in Nutrition reviews, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 7 papers, 1 of them a synthesis that pooled it.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
7 citing papers in PubMed, 1 synthesis or guideline pooled it.
- Pooled it
- Tibetan Butter Tea Consumption and Cognitive Performance Among Tibetan Adolescents at High Altitude.Nutrients · 2026Article
- Compositional Diversity and Functional Interactions of Bioactive Compounds in Japanese Green Tea: Focus on Matcha, Sencha, and Gyokuro.Molecules (Basel, Switzerland) · 2026Review
- Income, diet, and cognitive function: observational analyses and candidate metabolomic pathways identified by Mendelian randomization.The journal of prevention of Alzheimer's disease · 2026Observational
- Evolutionary and pan-genomic analysis of theFrontiers in plant science · 2026Article
- Effects of L-theanine on cognition, mood and sleep: evidence from human trials.Frontiers in nutrition · 2026Review
- Pharmaceutical Activities of Theanine: A Phytochemical Nutrient.Food science & nutrition · 2025Review
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
5 authors.
Funding
Abstract
contextThe bioactive compounds found in tea from Camellia sinensis, namely theanine, caffeine, and polyphenols, can potentially improve short-term and long-term health outcomes.
objectiveThe aim of this study was to assess the effects of tea, theanine alone, or theanine plus caffeine on cognition, mood, and sleep outcomes, using data from randomized controlled trials (RCTs) in healthy participants. DATA SOURCES: The Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, Embase, and Ovid Medline were searched up to and including August 2023. DATA EXTRACTION: Data relevant to the participants, interventions, comparisons, outcomes (ie, cognition, mood, and sleep), and study design were extracted. DATA ANALYSIS: Fifty RCTs were included in the review, of which 15 were eligible for at least 1 meta-analysis, most commonly performed by use of standardized mean differences (SMD), in random effects models. After intake of theanine plus caffeine, and of placebo, small-to-moderate differences were found between these interventions in the first hour (h1) and second hour (h2), that favoured theanine plus caffeine, with regard to cognition and mood outcomes such as choice reaction time (h1: SMD, -0.48; 95% CI, -1.01, 0.05), digit vigilance task accuracy (h2: SMD, 0.20; 95% CI, 0.02, 0.38), attention switching task accuracy (h2: SMD, 0.33; 95% CI, 0.13, 0.54), and overall mood (h2: SMD, 0.26; 95% CI,-0.10, 0.63). There was a small-to-moderate difference between the effects of theanine and placebo that favored theanine on choice reaction time (h1: SMD, -0.35; 95% CI,-0.61, -0.10). The CIs frequently highlighted the uncertainty surrounding the direction and magnitude of these differences.
conclusionsThis meta-analysis provides evidence that theanine plus caffeine, and theanine alone, could be beneficial for cognitive and mood outcomes. More research using tea beverages or tea-equivalent bioactive doses and research in free-living participants is needed. PROSPERO REGISTRATION NO: CRD42022351601.
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Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.