Meta-analysisindependent cross-checkabstract only checked★ key study I-GUT-07 in-depth review
Dietary fibre and health
Carbohydrate quality and human health: a series of systematic reviews and meta-analyses.
Overview
Reynolds A et al.. Lancet 2019 · PMID 30638909 · DOI 10.1016/S0140-6736(18)31809-9
People eating the most fibre had 15–30% lower risk of death and major chronic diseases.
Does the study support the specific claim? No · Methodological quality: high
Plain-language summary
Study explained simply
- What did the researchers want to find out?
Fibre and disease.
- How was the study done?
Meta-analyses.
- How many people, animals or samples were studied?
185 cohorts, 58 trials.
- What was actually found?
Lower disease risk.
- How large was the observed effect?
15–30%.
- What do the results mean in everyday life?
Fibre is good for health.
- What are the study's limitations?
Observational outcomes.
- What does it say about Elawady's specific claim?
Contradicts C-GUT-05.
- Do the results apply to Germany and Europe?
Applicable.
- What can explicitly not be concluded from this study?
Effect in IBS.
Scientific in-depth review
1. Full reference
- Authors
- Reynolds A et al.
- Journal
- Lancet
- Year
- 2019
- Identifier
- PMID 30638909 DOI 10.1016/S0140-6736(18)31809-9
- Verification
- verified – PubMed efetch 2026-10-25
- Retracted
- no
- Corrections
ErratumIn: Lancet. 2019 Feb 2;393(10170):406. doi: 10.1016/S0140-6736(19)30119-9.
- Extent checked
- abstract only
- Conflicts of interest and funding
not stated in abstract | Funding (abstract): Health Research Council of New Zealand, WHO, others
2. Research question
Carbohydrate quality (fibre, whole grains, GI) and non-communicable disease
3. Study design and population
- Study design
- Meta-analysis – Series of systematic reviews and meta-analyses of prospective studies and RCTs
- Population
Adults without chronic disease
- Country
Multinational
- Period
to 2017/2018
- Sample size
185 prospective studies (~135 million person-years); 58 trials (4,635)
- Inclusion and exclusion criteria
Excluded chronic disease, weight-loss and supplement trials
4. Methods and endpoints
- Exposure / intervention
Higher dietary fibre, whole grains
- Comparator
Lower intake
- Endpoints
Mortality, CHD, stroke, T2D, colorectal cancer, risk factors
- Statistical methods
Random effects; GRADE
5. Actual results
- Results
Highest vs lowest fibre: 15–30% lower all-cause and CV mortality, CHD, stroke, T2D, colorectal cancer; trials: lower weight, systolic BP, cholesterol; greatest benefit at 25–29 g/day.
- Absolute risks
not reported in abstract
- Authors' conclusion
Higher fibre and whole grain intakes; relationships could be causal; replace refined grains with whole grains.
6. Strengths
- Large
- Combines cohorts and trials
- GRADE moderate for fibre
7. Weaknesses
- Observational main outcomes
- Erratum
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 WHO-commissioned review.
9. Assessment of the statistical interpretation
Dose-response.
10. Relevance to the specific claim
11. Independent contrary findings
12. Transferability to Germany and Europe
High.
13. Overall methodological judgement
Strong evidence that fermentable fibre is beneficial.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | high |
| Risk of bias | low |
| Precision of results | high |
| Directness | direct |
| Reproducibility | replicated |
| Consistency with the overall evidence | consistent |
| Regional transferability | high |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
15. Linked fact checks
- Residues of incomplete digestion and the fermentation of hard-to-digest food in the gut are harmful waste that stimulates the immune, nervous and hormonal systems. – Studies contradicting or limiting the claim