Case-control studyindependent cross-checkabstract checked I-WHT-124 standard review
Iranian study links refined grains to heart disease, with a reporting problem
Association of whole and refined grains food consumption with coronary artery disease in a multi-center, case-control study of Iranian adults: Iran Premature Coronary Artery Disease (IPAD).
Overview
Tabesh F et al.. Nutr Metab Cardiovasc Dis 2025 · PMID 39986935 · DOI 10.1016/j.numecd.2025.103866
In an Iranian case-control study, whole grains were linked to 46% lower odds of coronary disease; the refined-grain result (OR 1.43) is reported with a confidence interval that includes no effect.
Does the study support the specific claim? Partly · Methodological quality: low
Plain-language summary
Study explained simply
- What did the researchers want to find out?
Grains and coronary disease in Iran.
- How was the study done?
Case-control study.
- How many people, animals or samples were studied?
3267 adults.
- What was actually found?
Whole grains protective; refined grains possibly harmful.
- How large was the observed effect?
OR 0.54 and 1.43.
- What do the results mean in everyday life?
Consistent direction with Western data for whole grains.
- What are the study's limitations?
Recall bias; inconsistent statistics.
- What does it say about Elawady's specific claim?
Weak support for the refined-grain claim.
- Do the results apply to Germany and Europe?
Low-moderate.
- What can explicitly not be concluded from this study?
Cannot establish that refined grains cause CAD.
Scientific in-depth review
1. Full reference
- Authors
- Tabesh F et al.
- Journal
- Nutr Metab Cardiovasc Dis
- Year
- 2025
- Identifier
- PMID 39986935 DOI 10.1016/j.numecd.2025.103866
- Verification
- verified – PubMed efetch 2026-10-26; Crossref works API 2026-10-26
- Retracted
- no
- Corrections
- none
- Extent checked
- abstract only
- Conflicts of interest and funding
No conflicts declared.
2. Research question
Are whole and refined grain foods associated with premature coronary artery disease in Iranian adults of different ethnicities?
3. Study design and population
- Study design
- Case-control study – Multicentre hospital-based case-control study (IPAD)
- Population
Iranian adults (Fars, Azari, Kurd, Arab, Lor, Gilak, Qashqaei, Bakhtiari) undergoing angiography
- Country
Iran
- Period
not stated in abstract
- Sample size
2099 cases, 1168 controls
- Inclusion and exclusion criteria
Cases: stenosis >=75% in >=1 vessel or >=50% left main; controls: normal angiogram
4. Methods and endpoints
- Exposure / intervention
Whole and refined grain foods (FFQ)
- Comparator
Lowest quartile
- Endpoints
Premature CAD
- Statistical methods
Logistic regression, full adjustment
5. Actual results
- Results
Top vs bottom quartile: whole grain foods OR 0.54 (0.40-0.72; P<0.001); refined grain foods OR 1.43 (95% CI 0.91-1.84; P=0.013) as reported.
- Absolute risks
not reported
- Authors' conclusion
Findings support increasing whole grain and reducing refined grain foods to reduce CAD risk.
6. Strengths
- Regional (includes Arab ethnicity)
- Angiographically defined cases and controls
7. Weaknesses
- Case-control: recall bias, reverse causation
- Controls are patients referred for angiography
- Reported refined-grain OR and CI are internally inconsistent
8. Risk of bias
- Orienting tool
- ROBINS-E
- Type of assessment
- simplified assessment (abstract only)
- Full formal assessment
- no
- Overall risk of bias
- high
- Rationale
Case-control design with hospital controls and dietary recall after diagnosis.
9. Assessment of the statistical interpretation
OR 1.43 is not centred in its CI (0.91-1.84; geometric centre 1.29), and a CI including 1 conflicts with P=0.013 (stats/C-WHT-03_04). The refined-grain result cannot be relied on as reported.
10. Relevance to the specific claim
Regional evidence pointing in the direction of the claim, but weak design and a reporting inconsistency.
11. Independent contrary findings
12. Transferability to Germany and Europe
Low-moderate.
13. Overall methodological judgement
Weak supporting evidence from the Middle East.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | low |
| Risk of bias | high |
| Precision of results | low |
| Directness | direct |
| Reproducibility | partly replicated |
| Consistency with the overall evidence | mixed |
| Regional transferability | high |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
Prospective Middle-Eastern cohorts.