Caffeine and Green Tea Extract: what the published research says
PubMed indexes 7 records that name Caffeine and Green Tea Extract together, either in the title or in an interaction, co-administration, or pharmacokinetic context. Each one is listed below with its study design and, where the abstract states one, the authors’ own conclusion, quoted and linked. This page reports that literature. It does not tell you whether to combine them.
Every statement below is attributed to a named, dated, linked source.
This page lists published research relevant to Caffeine and Green Tea Extract. It deliberately does not state whether the combination is safe, whether it interacts, in which direction, at what dose, or how far apart to take them.
A study appearing here is not proof that an interaction exists. Two substances can be named together in a paper that never tested them in combination, and a source listed as background may cover only one of them.
Findings are quoted from each abstract as the authors wrote them. NutriStack has not re-analysed, pooled, or reconciled them, and they may disagree with each other.
NutriStack’s own interaction assessment for this pair is not published here. It has not completed qualified-human clinical review, so it is withheld from search. See the publication gate.
Nothing here is medical advice. Decisions about prescription medication and supplements belong with your prescriber or pharmacist, who can see your full regimen.
The research
7 studies naming Caffeine and Green Tea Extract.
Strongest relevance first: papers naming both substances in the title, then human trials and systematic reviews.
“This 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.”
Names both Caffeine and Green Tea Extract in its title.
The British journal of nutrition · 2025 · PMID 40999690
Human subjects7708 participants
“Caffeine and coffee consumption was inversely associated with disability and/or mortality. Further research is needed to clarify whether high caffeine intake is safe and effective for older adults.”
Names both Caffeine and Green Tea Extract in its title.
The journal of nutrition, health & aging · 2014 · PMID 24522465
ReviewHuman subjects
“Special attention is drawn to caffeine physiological effect on human organism. Controversies concerning the possible caffeine influence on human physical and psychological health are briefly summarized and presented.”
Names both Caffeine and Green Tea Extract in its title.
“Taken together, these functional ingredients have the potential to produce significant effects on metabolic targets such as thermogenesis, and fat oxidation. An ethnic or genetic effect, and habitual caffeine or green tea catechin intake may act as confounders; this remains to be revealed.”
Names both Caffeine and Green Tea Extract in its title.
International journal of obesity (2005) · 2009 · PMID 19597519
Meta-AnalysisReviewHuman subjects
“Catechins or an epigallocatechin gallate (EGCG)-caffeine mixture have a small positive effect on WL and WM. The results suggest that habitual caffeine intake and ethnicity may be moderators, as they may influence the effect of catechins.”
Names Caffeine and Green Tea Extract together in an interaction, co-administration, or pharmacokinetic context.
“Epigallocatechin-3-O-gallate (EGCg) formed a 1 : 1 complex with β-cyclodextrin (CD), in which the aromatic A ring and a part of the heterocyclic C ring were included from the wide secondary hydroxyl group side of the β-CD cavity in aqueous solution, while the B rings and 3-O-gallate groups (B' rings) were left outside the cavity. In contrast, ENTGCg formed a 1 : 2 complex with β-CD, in which the aromatic A and B rings of ENTGCg were included by two molecules of β-CD.”
Names Caffeine and Green Tea Extract together in an interaction, co-administration, or pharmacokinetic context.
Limitations
What this evidence cannot tell you.
Search-based evidence indexes have real limits, and it is worth being explicit about them:
Selection. These records were found by searching PubMed titles and abstracts for both substance names alongside interaction and pharmacokinetic terms. Relevant work that phrases things differently, or is not indexed in PubMed, will be missing.
No effect size. The quoted conclusions are the authors’ words about their own study. We have not extracted effect direction or magnitude, and a single study’s conclusion is not a consensus.
Population mismatch. Findings in healthy volunteers, animals, or a specific patient group may not transfer to you, your dose, or your formulation.
Absence is not safety. Few published studies means the combination is under-studied, which is not the same as established as safe.
Nearby evidence
Other pairs with published research.
Pages covering Caffeine or Green Tea Extract alongside a different substance.
NutriStack is a free iPhone app for organising a supplement routine: what you take, when, and what the published record says about it. Its exploratory interaction checker covers Caffeine, Green Tea Extract, and several hundred other substances.
The checker is a research and organisation tool, not a clinical decision aid, and its per-pair assessments are excluded from search until they pass claim-level review.
NutriStack is an informational and organizational tool, not a medical service, and not a substitute for professional advice. Always consult a qualified healthcare professional before starting, stopping, or changing any supplement or medication.
