Cohort studyindependent cross-checkabstract checked I-GRN-119 standard review
French fries were linked to high blood pressure, chips were not
Potato intake and incidence of hypertension: results from three prospective US cohort studies.
Overview
Borgi L et al.. BMJ 2016 · PMID 27189229 · DOI 10.1136/bmj.i2351
In 187,000 US adults, eating French fries 4+ times a week was linked to 17% higher hypertension risk.
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?
Potatoes and hypertension.
- How was the study done?
Three cohorts.
- How many people, animals or samples were studied?
187,453 adults.
- What was actually found?
Fries linked; chips not.
- How large was the observed effect?
HR 1.17 for fries.
- What do the results mean in everyday life?
Limit fried potatoes.
- What are the study's limitations?
Self-report.
- What does it say about Elawady's specific claim?
Contradicts unrestricted fried potatoes.
- Do the results apply to Germany and Europe?
Moderate.
- What can explicitly not be concluded from this study?
Cannot prove causation.
Scientific in-depth review
1. Full reference
- Authors
- Borgi L et al.
- Journal
- BMJ
- Year
- 2016
- Identifier
- PMID 27189229 DOI 10.1136/bmj.i2351 · PMC4870381
- 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 financial relationships declared
2. Research question
Are baked/boiled potatoes, French fries or potato chips associated with incident hypertension?
3. Study design and population
- Study design
- Cohort study – Three prospective cohorts (NHS, NHS II, HPFS)
- Population
Non-hypertensive US adults
- Country
USA
- Period
not stated in abstract
- Sample size
187,453 (62,175 + 88,475 + 36,803)
- Inclusion and exclusion criteria
Non-hypertensive at baseline
4. Methods and endpoints
- Exposure / intervention
Potato intake by type
- Comparator
<1 serving/month
- Endpoints
Incident hypertension (self-report)
- Statistical methods
Cox models; random-effects pooling; substitution analysis
5. Actual results
- Results
>=4 servings/week vs <1/month: baked/boiled/mashed HR 1.11 (0.96-1.28; P trend 0.05); French fries 1.17 (1.07-1.27; P trend 0.001); potato chips 0.97 (0.87-1.08). Replacing one daily serving of baked/boiled/mashed potatoes with non-starchy vegetables: HR 0.93 (0.89-0.96).
- Absolute risks
not reported
- Authors' conclusion
Higher intake of baked, boiled or mashed potatoes and French fries was independently associated with hypertension.
6. Strengths
- Large cohorts, long follow-up
7. Weaknesses
- Self-reported hypertension
- Observational
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
Residual confounding.
9. Assessment of the statistical interpretation
Small relative risks; chips null for hypertension.
10. Relevance to the specific claim
Fried potatoes associated with hypertension; chips not.
11. Independent contrary findings
I-GRN-120 (total potato not associated with hypertension).
12. Transferability to Germany and Europe
Moderate.
13. Overall methodological judgement
Moderate-quality observational evidence.
| 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 | mixed |
| Regional transferability | moderate |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
Causality.
15. Linked fact checks
- Potatoes in all forms are allowed, including fried potatoes and packaged potato chips (crisps). – Studies with mixed or unclear results