Systematic reviewindependent cross-checkabstract only checked★ key study I-INTA-03 in-depth review
Is tea good or bad for health overall?
Tea Consumption and Health Outcomes: Umbrella Review of Meta-Analyses of Observational Studies in Humans.
Overview
Yi M et al.. Molecular nutrition & food research 2019 · PMID 31216091 · DOI 10.1002/mnfr.201900389
Across 96 meta-analyses, tea showed more benefits than harms; only very hot tea (>55-60 °C) was linked to oesophageal and gastric cancer.
Does the study support the specific claim? No · Methodological quality: moderate
Plain-language summary
Study explained simply
- What did the researchers want to find out?
Overview of tea and health
- How was the study done?
Umbrella review
- How many people, animals or samples were studied?
96 meta-analyses
- What was actually found?
More benefit than harm; harm only for very hot tea
- How large was the observed effect?
Lower risks at 2-3 cups/day
- What do the results mean in everyday life?
Normal tea drinking is safe for most people; let it cool
- What are the study's limitations?
Observational
- What does it say about Elawady's specific claim?
Contradicts 'dangerous drink'; supports a temperature caveat
- Do the results apply to Germany and Europe?
Moderate
- What can explicitly not be concluded from this study?
Causation
Scientific in-depth review
1. Full reference
- Authors
- Yi M et al.
- Journal
- Molecular nutrition & food research
- Year
- 2019
- Identifier
- PMID 31216091 DOI 10.1002/mnfr.201900389
- Verification
- verified – PubMed efetch 2026-10-25
- Retracted
- no
- Corrections
- none
- Extent checked
- abstract only
- Conflicts of interest and funding
Research support (non-US government) per PubMed record
2. Research question
Strength and validity of associations between tea consumption and diverse health outcomes
3. Study design and population
- Study design
- Systematic review – Umbrella review of meta-analyses of observational studies
- Population
All human populations in included meta-analyses
- Country
Multinational
- Period
Not stated in abstract
- Sample size
96 meta-analyses, 40 unique outcomes
- Inclusion and exclusion criteria
Meta-analyses of observational studies on tea consumption
4. Methods and endpoints
- Exposure / intervention
Tea consumption
- Comparator
Lower or no tea consumption
- Endpoints
Mortality, cardiovascular, metabolic, cancer, skeletal, cognitive, maternal outcomes
- Statistical methods
Umbrella synthesis; dose-response summaries
5. Actual results
- Results
Tea consumption showed greater benefit than harm; 2-3 cups/day associated with reduced total mortality, cardiac death, coronary artery disease, stroke and type 2 diabetes. Harmful associations for oesophageal and gastric cancer when tea is drunk hotter than 55-60 °C.
- Absolute risks
not reported
- Authors' conclusion
Tea consumption, except very hot tea, seems generally safe at usual intake; RCTs needed for causality.
6. Strengths
- Broad overview of many outcomes
- Identifies a specific harm (very hot tea)
7. Weaknesses
- Observational evidence only
- Overlapping meta-analyses
8. Risk of bias
- Orienting tool
- AMSTAR 2
- Type of assessment
- simplified assessment (abstract only)
- Full formal assessment
- no
- Overall risk of bias
- some concerns
- Rationale
Simplified judgement from abstract.
9. Assessment of the statistical interpretation
Associations, not causal effects; the temperature-related cancer signal is a genuine caveat.
10. Relevance to the specific claim
Overall benefit-harm balance of tea.
11. Independent contrary findings
Very hot tea and upper GI cancers.
12. Transferability to Germany and Europe
Moderate.
13. Overall methodological judgement
Usual tea drinking is generally safe; very hot tea is a specific risk.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | moderate |
| Risk of bias | some concerns |
| Precision of results | moderate |
| Directness | direct |
| Reproducibility | replicated |
| Consistency with the overall evidence | consistent |
| Regional transferability | moderate |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
Causality; added sugar; preparation strength.