Cohort studyindependent cross-checkfull text checked★ key study I-FRU-01 in-depth review
Which fruits are linked to diabetes?
Fruit consumption and risk of type 2 diabetes: results from three prospective longitudinal cohort studies.
Overview
Muraki I et al.. BMJ 2013 · PMID 23990623 · DOI 10.1136/bmj.f5001
Blueberries, grapes and apples linked to lower diabetes risk; juice and cantaloupe to slightly higher risk; glycaemic load did not explain the differences.
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?
Fruits and diabetes
- How was the study done?
Three cohorts
- How many people, animals or samples were studied?
187,382
- What was actually found?
Whole fruits mostly protective; juice harmful
- How large was the observed effect?
Juice HR 1.08; grapes 0.88; cantaloupe 1.10
- What do the results mean in everyday life?
Eat whole fruit rather than juice
- What are the study's limitations?
Observational; US
- What does it say about Elawady's specific claim?
Undermines GL argument for melon ban; supports whole fruit over juice
- Do the results apply to Germany and Europe?
Moderate
- What can explicitly not be concluded from this study?
Causation; watermelon specifically
Scientific in-depth review
1. Full reference
- Authors
- Muraki I et al.
- Journal
- BMJ
- Year
- 2013
- Identifier
- PMID 23990623 DOI 10.1136/bmj.f5001
- Verification
- verified – PubMed efetch 2026-10-25; full text via Europe PMC PMC3978819
- Retracted
- no
- Corrections
Erratum: BMJ 2013;347:f6935
- Extent checked
- full text
- Conflicts of interest and funding
ICMJE: no relevant financial relationships; NIH and MRC grants. Erratum BMJ 2013;347:f6935 (CI corrected).
2. Research question
Are individual fruits and fruit juice differentially associated with T2D?
3. Study design and population
- Study design
- Cohort study – Three prospective cohorts (NHS, NHS II, HPFS), pooled
- Population
66,105 + 85,104 women, 36,173 men
- Country
USA
- Period
1984-2009
- Sample size
187,382; 12,198 cases
- Inclusion and exclusion criteria
Free of major chronic disease
4. Methods and endpoints
- Exposure / intervention
10 individual fruits (cantaloupe included; watermelon asked sporadically); fruit juice
- Comparator
Per 3 servings/week
- Endpoints
Incident T2D
- Statistical methods
Cox; substitution; GI/GL groups
5. Actual results
- Results
Per 3 servings/week whole fruit HR 0.98 (0.97-0.99). Blueberries 0.74 (0.66-0.83); grapes/raisins 0.88 (0.83-0.93); apples/pears 0.93 (0.90-0.96); bananas 0.95; grapefruit 0.95; oranges 0.99; strawberries 1.03; cantaloupe 1.10 (1.02-1.18). Fruit juice 1.08 (1.05-1.11). Full text: fruits grouped by GL per serving - high GL (8.1-19.2): prunes, bananas, grapes, raisins, apples, pears; moderate (5.7-8.0): cantaloupe, blueberries, oranges; low (1.3-5.6): peaches, plums, apricots, strawberries, grapefruit. High-GL fruits associated with LOWER risk; GI/GL did not account for associations. GL per serving 6.2 raw orange vs 13.4 orange juice; fibre 3.1 vs 0.5 g. Substitution of whole fruits for juice associated with lower risk except strawberries and cantaloupe.
- Absolute risks
12,198 cases in 3,464,641 person-years
- Authors' conclusion
Specific whole fruits (blueberries, grapes, apples) associated with lower T2D risk; fruit juice with higher risk.
6. Strengths
- Large, repeated FFQ
- Individual fruits
- GL analysis
7. Weaknesses
- US health professionals
- Watermelon not regularly measured
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
9. Assessment of the statistical interpretation
Small HRs per 3 servings/week.
10. Relevance to the specific claim
Central for C-FRU-01, C-FRU-03, C-FRU-04, C-FRU-05.
11. Independent contrary findings
12. Transferability to Germany and Europe
Moderate.
13. Overall methodological judgement
Key study: GL ranking contradicts the archive's melon rationale; juice associated with higher risk; small cantaloupe signal exists.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | high |
| Risk of bias | some concerns |
| Precision of results | high |
| Directness | direct |
| Reproducibility | partly replicated |
| Consistency with the overall evidence | consistent |
| Regional transferability | moderate |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
Cantaloupe signal replication.
15. Linked fact checks
- Watermelon and melon (cantaloupe) should be avoided; the archive's food page supports this with studies showing that a high dietary glycaemic load raises type 2 diabetes risk. – Studies with mixed or unclear results
- Fruit juices, including canned juices and nectars, are allowed or preferred (mango only as juice; on one third-party site fresh juices are forbidden and only canned juices allowed). – Studies contradicting or limiting the claim
- Apples and pears should be eaten only peeled. – Studies contradicting or limiting the claim
- Sweet fruits such as dates, grapes, figs and mango need not be avoided; conventional diets wrongly restrict them and push bland fruit. – Studies supporting the claim