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.

Original statement

No Arabic original wording available.

Translation

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.

Origin

Source status

Archive editors

Attribution

Archive editors

Origin

https://eltayebat.com/rule/leafy-greens-cucurbits/

Attribution uncertainty

Archive featured card and narrative on Moraïs et al. 2024; presented as 'the deepest support for Dr. Diaa's ruminant argument'.

Claimed mechanism

Loss of cellulosome-producing Ruminococcus species.

Claimed health effect

Inability to ferment plant cell walls.

Population concerned

Industrialised populations

Geographic restriction by Elawady

none found

Scientific assessment

Mostly false – Essential parts of the statement are not supported by the evidence or are strongly exaggerated.

Certainty of evidence: moderate – Further research may still affect the assessment.

1. What was claimed?

Modern humans lack microbes to ferment cellulose, so vegetables are the wrong fuel.

2. What is demonstrably correct?

Correctly reported: cellulosome-producing ruminococci are abundant in hunter-gatherers, rural and ancient populations and rare in industrialised societies; one species likely came from ruminants.

3. What is wrong or exaggerated?

The paper is titled 'Cryptic diversity of cellulose-degrading gut bacteria in industrialized humans', i.e. such bacteria exist in industrialised humans, although rarely. Cellulose is only one component of plant fibre; pectins, hemicelluloses, inulin and resistant starch are fermented by many common gut bacteria. The paper says nothing about vegetables being harmful. The authors report these species in at most 4.6% of industrialised samples versus about 20-43% in non-industrialised and ancient samples, attribute their rarity to the westernised lifestyle, and suggest re-introducing them through targeted diets and specialised probiotics - the opposite of the inference that humans are not built to digest plant fibre. If anything, the authors interpret the loss as a consequence of the westernised lifestyle, which suggests that higher plant-fibre intake supports these microbes.

4. What remains unclear?

Whether low abundance of cellulose degraders has health consequences is unknown.

5. Which studies support it?

None for the archive's conclusion.

6. Which studies contradict it?

Moraïs 2024 abstract itself; Koh 2016; Reynolds 2019.

7. What applies to Germany and Europe?

Applies to industrialised populations including Germany.

8. What is known about Egypt?

Not specific.

9. What practical conclusion is appropriate?

The study is about microbiome ecology; it does not support avoiding vegetables.

Assessment details

Rationale for certainty of evidence

The paper's abstract states that humans, like all mammals, depend on the gut microbiome for cellulose digestion and that cellulose-degrading species are present but rare in industrialised populations; it does not show that the gut cannot ferment other plant cell-wall fibres, and it does not study health effects of eating vegetables.

Source quality

High-quality basic-science paper; archive interpretation goes beyond the findings.

Regional transferability

The finding concerns industrialised populations (including Germany); rural Egyptian populations were not specifically mentioned in the abstract.

Individual exceptions

Not applicable.

Regional scope of the claim

not specified

Last reviewed

25 October 2026 provisional

In plain language

The archive cites a 2024 study as proof that modern humans cannot digest plant fibre. The study actually found cellulose-digesting bacteria in humans, common in traditional and rural populations and rare in industrialised ones. It did not test whether eating vegetables is harmful. Many other fibre types in vegetables are fermented by common gut bacteria, and the loss of these microbes may itself reflect low-fibre western diets.

Studies on this claim

Regional context

Germany / EU

Applies to industrialised populations including Germany.

Egypt

Not specific.

• Pesticide residues in fruit and vegetables on the EU/German market (incl. imports from Egypt)
• Pesticide residues in produce sold on the Egyptian domestic market
• Nitrate in leafy vegetables
• Microbiological safety of fresh produce, herbs and spices

What applies in my country?

General scientific assessment

Mostly false The study is misread: it documents rare, not absent, cellulose degraders and makes no claim against vegetables.

The following areas of food safety are relevant to this statement:

• Pesticides and pesticide residues
• Contaminants (heavy metals, PFAS, PCBs, dioxins, nitrate)
• Pathogens (Salmonella, Campylobacter, etc.)

Fruit and vegetables

Limits: legal rules describe what is allowed, not what every single food contains. Measurement data come from samples and are meaningful only together with their method details.

Country of residence or purchase Compare with another country

References

1. From Dietary Fiber to Host Physiology: Short-Chain Fatty Acids as Key Bacterial Metabolites.. Koh A et al.. Cell 2016 · PMID 27259147 · DOI 10.1016/j.cell.2016.05.041
2. Carbohydrate quality and human health: a series of systematic reviews and meta-analyses.. Reynolds A et al.. Lancet 2019 · PMID 30638909 · DOI 10.1016/S0140-6736(18)31809-9
3. Cryptic diversity of cellulose-degrading gut bacteria in industrialized humans.. Moraïs S et al.. Science 2024 · PMID 38484069 · DOI 10.1126/science.adj9223