Meta-analysisindependent cross-checkabstract checked I-FAT-107 standard review
Omega-6 oils: no clear heart benefit or harm in trials
Omega-6 fats for the primary and secondary prevention of cardiovascular disease.
Overview
Hooper L et al.. Cochrane Database Syst Rev 2018 · PMID 30488422 · DOI 10.1002/14651858.CD011094.pub4
Mortality RR 1.00; possible small reduction in heart attacks.
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?
Test omega-6 fats in trials.
- How was the study done?
Cochrane review.
- How many people, animals or samples were studied?
19 RCTs, 6461 people.
- What was actually found?
No clear effect on deaths; lower cholesterol.
- How large was the observed effect?
Mortality RR 1.00.
- What do the results mean in everyday life?
Corn/sunflower oils are acceptable but not proven protective.
- What are the study's limitations?
Imprecise.
- What does it say about Elawady's specific claim?
Neutral.
- Do the results apply to Germany and Europe?
Applicable.
- What can explicitly not be concluded from this study?
Cannot show olive oil is worse.
Scientific in-depth review
1. Full reference
- Authors
- Hooper L et al.
- Journal
- Cochrane Database Syst Rev
- Year
- 2018
- Identifier
- PMID 30488422 DOI 10.1002/14651858.CD011094.pub4
- Verification
- verified – PubMed efetch 2026-10-26
- Retracted
- no
- Corrections
- none
- Extent checked
- abstract only
- Conflicts of interest and funding
WHO funded the review update.
2. Research question
Does increasing omega-6 fat intake affect CVD and mortality?
3. Study design and population
- Study design
- Meta-analysis – Cochrane systematic review and meta-analysis of RCTs (>=12 months)
- Population
Adults with or without CVD
- Country
Multinational
- Period
searches to 2017
- Sample size
19 RCTs; 6461 participants
- Inclusion and exclusion criteria
RCTs >=12 months
4. Methods and endpoints
- Exposure / intervention
Increased omega-6 (LA, GLA)
- Comparator
Lower omega-6
- Endpoints
Mortality, CVD events, MI, lipids
- Statistical methods
Random effects; GRADE
5. Actual results
- Results
All-cause mortality RR 1.00 (0.88-1.12; low quality); CVD events 0.97 (0.81-1.15); CVD mortality 1.09 (0.76-1.55; very low); CHD events 0.88 (0.66-1.17); MI 0.88 (0.76-1.02; low); total cholesterol -0.33 mmol/L (high quality); NNT 53 for MI (authors).
- Absolute risks
not reported
- Authors' conclusion
No evidence that increasing omega-6 fats reduces cardiovascular outcomes other than MI; benefits remain to be proven; may benefit people at high MI risk.
6. Strengths
- Cochrane methods
- Unpublished data
7. Weaknesses
- Few low-risk-of-bias trials
- Imprecise
8. Risk of bias
- Orienting tool
- AMSTAR 2
- Type of assessment
- simplified assessment (abstract only)
- Full formal assessment
- no
- Overall risk of bias
- low
- Rationale
High-quality review.
9. Assessment of the statistical interpretation
Neutral to slightly favourable; wide CIs.
10. Relevance to the specific claim
Corn and sunflower oils (rich in linoleic acid) are not shown to reduce CVD events in RCTs, nor to cause harm overall; they lower cholesterol.
11. Independent contrary findings
Cohorts (I-FAT-05) show lower CHD with LA.
12. Transferability to Germany and Europe
Applicable.
13. Overall methodological judgement
Neutral RCT evidence for omega-6 oils.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | high |
| Risk of bias | low |
| Precision of results | low |
| Directness | direct |
| Reproducibility | unknown |
| Consistency with the overall evidence | mixed |
| Regional transferability | moderate |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
Long-term RCTs.