Meta-analysisindependent cross-checkfull text checked★ key study I-EGG-109 in-depth review
Large review links eggs to slightly higher heart risk, mainly in the USA
Associations of Dietary Cholesterol, Serum Cholesterol, and Egg Consumption With Overall and Cause-Specific Mortality: Systematic Review and Updated Meta-Analysis.
Overview
Zhao B et al.. Circulation 2022 · PMID 35360933 · DOI 10.1161/CIRCULATIONAHA.121.057642
Each extra egg per day: 4% higher CVD risk overall (RR 1.04), 8% in US studies, none in Asian studies.
Does the study support the specific claim? Partly · Methodological quality: moderate
Plain-language summary
Study explained simply
- What did the researchers want to find out?
Combine all cohort data on eggs, cholesterol and death.
- How was the study done?
Finnish cohort plus meta-analysis of 3.6 million people.
- How many people, animals or samples were studied?
27,078 men; 49 estimates.
- What was actually found?
Small positive association, strongest in US studies.
- How large was the observed effect?
RR 1.04 (1.00-1.08) per 50 g egg/day.
- What do the results mean in everyday life?
Very high egg intake might slightly increase heart risk in some populations; moderate intake is a small issue at most.
- What are the study's limitations?
Observational; big differences between studies.
- What does it say about Elawady's specific claim?
Partly supports the archive's direction but with a much smaller and region-dependent effect.
- Do the results apply to Germany and Europe?
Borderline in Europe.
- What can explicitly not be concluded from this study?
It cannot prove that eggs cause heart disease.
Scientific in-depth review
1. Full reference
- Authors
- Zhao B et al.
- Journal
- Circulation
- Year
- 2022
- Identifier
- PMID 35360933 DOI 10.1161/CIRCULATIONAHA.121.057642
- 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
ATBC supported by the US National Cancer Institute intramural programme; authors declared no competing interests (full text).
2. Research question
Are dietary cholesterol, serum cholesterol and egg consumption associated with overall and cause-specific mortality?
3. Study design and population
- Study design
- Meta-analysis – Prospective cohort analysis (ATBC Study, Finnish male smokers) plus systematic review and dose-response meta-analysis of cohort studies (PROSPERO CRD42021272756)
- Population
ATBC: 27,078 Finnish male smokers aged 50-69; meta-analysis: 49 risk estimates, 3,601,401 participants
- Country
Finland (cohort); USA, Europe, Asia (meta-analysis)
- Period
ATBC recruited 1985-1988, follow-up up to 31 years
- Sample size
ATBC 27,078 (22,035 deaths); meta-analysis 3.6 million participants, 255,479 events
- Inclusion and exclusion criteria
not detailed in abstract
4. Methods and endpoints
- Exposure / intervention
Dietary cholesterol, egg intake (per 50 g/day), serum total cholesterol
- Comparator
Lower intake
- Endpoints
All-cause, CVD and cause-specific mortality; CVD (meta-analysis)
- Statistical methods
Cox models with absolute risk differences; random-effects dose-response meta-analysis; Egger tests; Newcastle-Ottawa scale
5. Actual results
- Results
ATBC: per 300 mg/day cholesterol HR 1.10 (overall) and 1.13 (CVD mortality); per 50 g egg/day HR 1.06 and 1.09 (all P<0.0001); egg-mortality associations diminished after adjustment for dietary cholesterol. Meta-analysis: per 50 g egg/day CVD RR 1.04 (1.00-1.08), I2 80.1%; US 1.08 (1.02-1.14); Europe 1.05 (0.98-1.14); Asia 0.96 (0.87-1.06); P-interaction 0.02.
- Absolute risks
31-year absolute risk differences were computed in the cohort (values not extracted here).
- Authors' conclusion
Greater dietary cholesterol and egg consumption were associated with increased overall and CVD mortality; findings support restricted dietary cholesterol intake.
6. Strengths
- Very large updated meta-analysis
- Long follow-up cohort with absolute risk differences
- Explores regional heterogeneity
7. Weaknesses
- Cohort limited to male smokers
- High heterogeneity (I2 80%)
- Single baseline FFQ
- Observational, residual confounding possible
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 evidence; heterogeneity largely by region; simplified judgement.
9. Assessment of the statistical interpretation
Recomputed US vs Asia difference z = 2.04, p = 0.04 (stats/C-EGG-04_regional_heterogeneity.py). The pooled RR of 1.04 per egg/day is small and the association is confined to US (and borderline European) cohorts.
10. Relevance to the specific claim
Strongest recent support for a modest positive egg-CVD association; also shows the association is absent in Asian cohorts.
11. Independent contrary findings
Drouin-Chartier 2020 (I-EGG-01), Krittanawong 2021 (I-EGG-110), PURE (I-EGG-02) found no association at moderate intake.
12. Transferability to Germany and Europe
Europe borderline (RR 1.05, 0.98-1.14). Egypt: no direct data; Middle East cohort (Isfahan, I-EGG-111) null.
13. Overall methodological judgement
Credible but modest positive association concentrated in US data; it supports caution with high intakes, not a general egg ban.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | moderate |
| Risk of bias | some concerns |
| Precision of results | high |
| Directness | direct |
| Reproducibility | partly replicated |
| Consistency with the overall evidence | inconsistent |
| Regional transferability | moderate |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
Why regional differences exist (accompanying foods, cooking, baseline diet).