Cohort studyindependent cross-checkfull text checked★ key study I-EGG-116 in-depth review
Big pooled study: eggs linked to only slightly more fatal prostate cancer, in North America
Associations between unprocessed red and processed meat, poultry, seafood and egg intake and the risk of prostate cancer: A pooled analysis of 15 prospective cohort studies.
Overview
Wu K et al.. Int J Cancer 2016 · PMID 26685908 · DOI 10.1002/ijc.29973
Fatal prostate cancer RR 1.14 (1.00-1.30) for about 3.5+ eggs/week; no link outside North America.
Does the study support the specific claim? Partly · Methodological quality: high
Plain-language summary
Study explained simply
- What did the researchers want to find out?
Pool cohorts on meat, eggs and prostate cancer.
- How was the study done?
Pooled analysis of 15 cohorts.
- How many people, animals or samples were studied?
842,149 men.
- What was actually found?
Small association of eggs with advanced/fatal cancer in North America only.
- How large was the observed effect?
RR 1.14.
- What do the results mean in everyday life?
If there is any effect, it is small and not seen in Europe or Asia.
- What are the study's limitations?
Observational; one diet measurement.
- What does it say about Elawady's specific claim?
The 81% figure is not representative of the overall evidence.
- Do the results apply to Germany and Europe?
No association in non-North-American cohorts.
- What can explicitly not be concluded from this study?
It cannot show that eggs cause prostate cancer.
Scientific in-depth review
1. Full reference
- Authors
- Wu K et al.
- Journal
- Int J Cancer
- Year
- 2016
- Identifier
- PMID 26685908 DOI 10.1002/ijc.29973
- Verification
- verified – PubMed efetch 2026-10-26; Crossref works API 2026-10-26
- Retracted
- no
- Corrections
- none
- Extent checked
- full text
- Conflicts of interest and funding
NCI/NIH and Cancer Research UK grants (PubMed); author manuscript in PMC.
2. Research question
Are meat, poultry, seafood and egg intakes associated with prostate cancer by stage and fatality?
3. Study design and population
- Study design
- Cohort study – Pooled analysis of individual data from 15 prospective cohorts (Pooling Project)
- Population
842,149 men in 15 cohorts (North America, Europe, Japan, Australia)
- Country
Multinational
- Period
Cohort baselines from the 1980s-1990s
- Sample size
842,149 men; 52,683 incident cases incl. 4,924 advanced
- Inclusion and exclusion criteria
not detailed in abstract
4. Methods and endpoints
- Exposure / intervention
Egg intake >=25 g/day (about 3.5 eggs/week)
- Comparator
<5 g/day
- Endpoints
Total, advanced and fatal prostate cancer
- Statistical methods
Study-specific Cox models pooled with random effects; tests for regional heterogeneity
5. Actual results
- Results
Eggs >=25 vs <5 g/day: advanced prostate cancer RR 1.14 (1.01-1.28; p-trend 0.01); fatal RR 1.14 (1.00-1.30; p-trend 0.01). Positive egg associations were limited to North American studies; the regional difference was statistically significant for eggs. Poultry was inversely associated with fatal cancer (RR 0.69, 0.59-0.82).
- Absolute risks
not reported
- Authors' conclusion
Higher egg intake was associated with a modestly higher risk of advanced and fatal prostate cancer, limited to North American studies; regional differences warrant investigation.
6. Strengths
- Very large pooled individual-level analysis
- Harmonised exposure and outcome definitions
7. Weaknesses
- Baseline diet only
- Residual confounding
- Includes HPFS, the source cohort of Richman 2011
8. Risk of bias
- Orienting tool
- ROBINS-E
- Type of assessment
- simplified assessment (abstract only)
- Full formal assessment
- no
- Overall risk of bias
- some concerns
- Rationale
Observational; simplified judgement.
9. Assessment of the statistical interpretation
Fatal RR 1.14 with SE 3.6 times smaller than Richman 2011 (stats/C-EGG-06_prostate.py): the precise pooled estimate is much smaller than the 81% figure.
10. Relevance to the specific claim
The strongest data on eggs and fatal prostate cancer: a modest 14% association, confined to North America, rather than 81%.
11. Independent contrary findings
No association outside North America.
12. Transferability to Germany and Europe
European cohorts showed no positive association; Egypt: no data.
13. Overall methodological judgement
Partial support for a weak association; does not support the archive's effect size or general applicability.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | high |
| Risk of bias | some concerns |
| Precision of results | high |
| Directness | direct |
| Reproducibility | partly replicated |
| Consistency with the overall evidence | inconsistent |
| Regional transferability | low |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
Why only North American cohorts show the association.
15. Linked fact checks
- Eating 2.5 or more eggs per week is associated with an 81% higher risk of lethal prostate cancer. – Studies with mixed or unclear results