Cohort studyindependent cross-checkabstract checked★ key study I-CHK-102 in-depth review
More poultry linked to slightly more heart disease in US cohorts
Associations of Processed Meat, Unprocessed Red Meat, Poultry, or Fish Intake With Incident Cardiovascular Disease and All-Cause Mortality.
Overview
Zhong VW et al.. JAMA Intern Med 2020 · PMID 32011623 · DOI 10.1001/jamainternmed.2019.6969
Two extra servings a week were linked to 4% more cardiovascular events (about 1 extra case per 100 people over 30 years), but not to more deaths.
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?
Are processed meat, red meat, poultry or fish associated with incident CVD and all-cause mortality?
- How was the study done?
Pooled individual-level analysis of 6 US prospective cohorts
- How many people, animals or samples were studied?
29,682 participants; 6,963 CVD events; 8,875 deaths
- What was actually found?
Poultry: incident CVD adjusted HR 1.04 (95% CI 1.01-1.06), 30-year absolute risk difference 1.03% (0.36-1.70); all-cause mortality HR 0.99 (0.97-1.02), ARD -0.28% (-1.00 to 0.44).
- How large was the observed effect?
Poultry: incident CVD adjusted HR 1.04 (95% CI 1.01-1.06), 30-year absolute risk difference 1.03% (0.36-1.70); all-cause mortality HR 0.99 (0.97-1.02), ARD -0.28% (-1.00 to 0.44).
- What do the results mean in everyday life?
A very small statistical link that may reflect how chicken is cooked (e.g. fried).
- What are the study's limitations?
Single baseline diet assessment; Preparation methods (frying, skin) not separated in abstract; Residual confounding possible
- What does it say about Elawady's specific claim?
Only weak and inconsistent support; not shown in meta-analyses of all cohorts (I-CHK-101).
- Do the results apply to Germany and Europe?
US diet; frying habits may differ from Europe/Egypt.
- What can explicitly not be concluded from this study?
Cannot show that chicken causes heart disease.
Scientific in-depth review
1. Full reference
- Authors
- Zhong VW et al.
- Journal
- JAMA Intern Med
- Year
- 2020
- Identifier
- PMID 32011623 DOI 10.1001/jamainternmed.2019.6969
- Verification
- verified – PubMed efetch 2026-10-26; Crossref 2026-10-26
- Retracted
- no
- Corrections
- none
- Extent checked
- abstract only
- Conflicts of interest and funding
NIH (NHLBI) funding listed in PubMed
2. Research question
Are processed meat, red meat, poultry or fish associated with incident CVD and all-cause mortality?
3. Study design and population
- Study design
- Cohort study – Pooled individual-level analysis of 6 US prospective cohorts
- Population
US adults, mean age 53.7 y
- Country
USA
- Period
baseline 1985-2002, follow-up to 2016 (median 19 y)
- Sample size
29,682 participants; 6,963 CVD events; 8,875 deaths
- Inclusion and exclusion criteria
as described in the abstract
4. Methods and endpoints
- Exposure / intervention
Poultry intake per 2 servings/week
- Comparator
Lower intake
- Endpoints
Incident CVD; all-cause mortality
- Statistical methods
as reported in the abstract
5. Actual results
- Results
Poultry: incident CVD adjusted HR 1.04 (95% CI 1.01-1.06), 30-year absolute risk difference 1.03% (0.36-1.70); all-cause mortality HR 0.99 (0.97-1.02), ARD -0.28% (-1.00 to 0.44).
- Absolute risks
30-year ARD for CVD 1.03% (0.36-1.70) per 2 servings/week
- Authors' conclusion
Higher poultry intake was associated with a small increased risk of incident CVD but not with all-cause mortality.
6. Strengths
- Individual-level data, long follow-up
- Absolute risk differences reported
7. Weaknesses
- Single baseline diet assessment
- Preparation methods (frying, skin) not separated in abstract
- 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; diet measured once.
9. Assessment of the statistical interpretation
HR 1.04 per 2 servings/week; 30-year ARD about 1 percentage point (NNH about 97 over 30 years). The authors note preparation may explain the finding (full text not read).
10. Relevance to the specific claim
Strongest observational signal of a small adverse association of poultry with CVD.
11. Independent contrary findings
12. Transferability to Germany and Europe
13. Overall methodological judgement
Two extra servings a week were linked to 4% more cardiovascular events (about 1 extra case per 100 people over 30 years), but not to more deaths.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | moderate |
| Risk of bias | some concerns |
| Precision of results | high |
| Directness | direct |
| Reproducibility | not replicated |
| Consistency with the overall evidence | mixed |
| Regional transferability | moderate |
| Adequacy of the interpretation (by the archive) | not applicable |