Randomised controlled trialindependent cross-checkabstract only checked I-FAT-06 standard review
Old corn-oil trial: cholesterol fell but deaths did not
Re-evaluation of the traditional diet-heart hypothesis: analysis of recovered data from Minnesota Coronary Experiment (1968-73).
Overview
Ramsden CE et al.. BMJ 2016 · PMID 27071971 · DOI 10.1136/bmj.i1246
No mortality benefit; HR 1.22 death per 30 mg/dL cholesterol drop.
Does the study support the specific claim? Unclear · Methodological quality: low
Plain-language summary
Study explained simply
- What did the researchers want to find out?
Re-test the diet-heart hypothesis.
- How was the study done?
Recovered RCT data + meta-analysis.
- How many people, animals or samples were studied?
9,423 residents.
- What was actually found?
No benefit on death.
- How large was the observed effect?
Meta-analysis CHD mortality 1.13 (0.83-1.54).
- What do the results mean in everyday life?
Uncertainty about seed oils vs animal fat.
- What are the study's limitations?
Old, institutional trial.
- What does it say about Elawady's specific claim?
Adds uncertainty.
- Do the results apply to Germany and Europe?
Moderate.
- What can explicitly not be concluded from this study?
That animal fats are better.
Scientific in-depth review
1. Full reference
- Authors
- Ramsden CE et al.
- Journal
- BMJ
- Year
- 2016
- Identifier
- PMID 27071971 DOI 10.1136/bmj.i1246
- Verification
- verified – PubMed efetch 2026-10-25
- Retracted
- no
- Corrections
ErratumIn: BMJ. 2024 Jun 28;385:q1450. doi: 10.1136/bmj.q1450.
- Extent checked
- abstract only
- Conflicts of interest and funding
Competing interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf and declare: support from the Intramural Program of the National Institute on Alcohol Abuse and Alcoholism for the submitted work; no financial relationships with any organizations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work. Grants listed in PubMed: NCCIH NIH HHS, PHS HHS
2. Research question
Does replacing SFA with linoleic-acid-rich vegetable oil reduce CHD and death?
3. Study design and population
- Study design
- Randomised controlled trial – Re-analysis of recovered RCT data (Minnesota Coronary Experiment 1968-73) plus systematic review/meta-analysis of RCTs.
- Population
9,423 institutionalised women and men aged 20-97
- Country
USA
- Period
1968-73
- Sample size
9,423 (2,355 exposed >=1 year); 5 RCTs (n=10,808) in meta-analysis
- Inclusion and exclusion criteria
Nursing home/mental hospital residents.
4. Methods and endpoints
- Exposure / intervention
Corn oil and corn-oil margarine diet
- Comparator
Diet high in animal fats/common margarines
- Endpoints
All-cause death; autopsy atherosclerosis.
- Statistical methods
Kaplan-Meier, Cox; meta-analysis.
5. Actual results
- Results
Serum cholesterol -13.8% vs -1.0%; no mortality benefit; HR 1.22 (1.14-1.32) for death per 30 mg/dL cholesterol reduction; meta-analysis CHD mortality 1.13 (0.83-1.54), all-cause 1.07 (0.90-1.27). Erratum 2024.
- Absolute risks
not reported
- Authors' conclusion
Replacement lowers cholesterol but evidence does not support reduced CHD or all-cause mortality; incomplete publication contributed to overestimation of benefits.
6. Strengths
- Recovered unpublished RCT data
7. Weaknesses
- Institutionalised population; short exposure for many
- Control diet contained trans-fat margarines
- Old trial
8. Risk of bias
- Orienting tool
- RoB 2
- Type of assessment
- simplified assessment (abstract only)
- Full formal assessment
- no
- Overall risk of bias
- high
- Rationale
High attrition/short exposure; historical data.
9. Assessment of the statistical interpretation
Null to unfavourable; wide CIs in meta-analysis.
10. Relevance to the specific claim
Mixed for C-FAT-04 (caution about linoleic-acid oils).
11. Independent contrary findings
12. Transferability to Germany and Europe
Moderate.
13. Overall methodological judgement
Important caveat, low certainty.
| 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 | inconsistent |
| Regional transferability | moderate |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
Role of trans fats in control diets.