Otherindependent cross-checkabstract checked I-VEG-131 standard review
Every person tested had gut microbes that break down spinach cell walls
The cellulose-degrading microbial community of the human gut varies according to the presence or absence of methanogens.
Overview
Chassard C et al.. FEMS Microbiol Ecol 2010 · PMID 20662929 · DOI 10.1111/j.1574-6941.2010.00941.x
French researchers found bacteria able to degrade spinach cell walls in all volunteers, of different types depending on methane production.
Does the study support the specific claim? No · Methodological quality: moderate
Plain-language summary
Study explained simply
- What did the researchers want to find out?
Characterise human cellulose degraders.
- How was the study done?
Culture and PCR.
- How many people, animals or samples were studied?
Volunteers (n not in abstract).
- What was actually found?
Degraders present in all.
- How large was the observed effect?
Not applicable.
- What do the results mean in everyday life?
Modern European guts can ferment vegetable cell walls.
- What are the study's limitations?
Small lab study.
- What does it say about Elawady's specific claim?
Contradicts the claim.
- Do the results apply to Germany and Europe?
European.
- What can explicitly not be concluded from this study?
Cannot quantify fermentation in vivo.
Scientific in-depth review
1. Full reference
- Authors
- Chassard C et al.
- Journal
- FEMS Microbiol Ecol
- Year
- 2010
- Identifier
- PMID 20662929 DOI 10.1111/j.1574-6941.2010.00941.x
- Verification
- verified – PubMed efetch 2026-10-26; Crossref 2026-10-26
- Retracted
- no
- Corrections
- none
- Extent checked
- abstract only
- Conflicts of interest and funding
not stated in abstract
2. Research question
How does the cellulose-degrading community of the human gut differ by methane status?
3. Study design and population
- Study design
- Other – Microbiological study: culture of cellulose-degrading bacteria from human faeces using spinach cell-wall substrate; real-time PCR
- Population
Methane-excreting and non-methane-excreting human volunteers
- Country
France
- Period
not stated in abstract
- Sample size
not stated in abstract
- Inclusion and exclusion criteria
not stated in abstract
4. Methods and endpoints
- Exposure / intervention
Methane status
- Comparator
Methane vs non-methane excretors
- Endpoints
Cellulose-degrading microorganisms (culture and qPCR)
- Statistical methods
Descriptive
5. Actual results
- Results
Cell-wall-spinach (CWS) degrading microorganisms were present in all individuals; main cellulose degraders were Bacteroidetes in non-methane excretors and Firmicutes (ruminococci) in methane excretors.
- Absolute risks
not reported
- Authors' conclusion
The structure of the cellulolytic community varies with the presence of methanogens in the human gut.
6. Strengths
- Uses a vegetable (spinach) cell-wall substrate
7. Weaknesses
- Small; sample size not in abstract
- In vitro culture
8. Risk of bias
- Orienting tool
- none applicable
- Type of assessment
- simplified assessment (abstract only)
- Full formal assessment
- no
- Overall risk of bias
- not assessable
- Rationale
Laboratory study.
9. Assessment of the statistical interpretation
not applicable
10. Relevance to the specific claim
Shows that microbes able to degrade vegetable cell walls were found in every individual tested in an industrialised country.
11. Independent contrary findings
Moraïs 2024: cellulosome-producing ruminococci rare in industrialised people (but other degraders exist).
12. Transferability to Germany and Europe
French volunteers.
13. Overall methodological judgement
Contradicts the claim that industrialised guts lack the machinery to ferment plant cell walls.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | moderate |
| Risk of bias | not assessable |
| Precision of results | not applicable |
| Directness | direct |
| Reproducibility | partly replicated |
| Consistency with the overall evidence | consistent |
| Regional transferability | high |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
Quantitative contribution of each group.
15. Linked fact checks
- A 2024 Science paper shows that industrialised humans have lost the cellulose-degrading gut bacteria, so the modern human gut 'was never built to digest cellulose' and no longer carries the machinery to ferment plant cell walls. – Studies contradicting or limiting the claim
- Humans, having a single stomach, cannot digest the cellulose in vegetables (unlike ruminants), so greens and legumes cause gas and bloating and are food made for animals, not for humans. – Studies contradicting or limiting the claim