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.

Original statement

«الجهاز الهضمي للحيوانات المجترة تستطيع هضم السليلوز الموجود في الخضروات بكفاءة بفضل معدتها المتعددة والبكتيريا الخاصة»، أمّا «الإنسان بمعدته الواحدة لا يهضم السليلوز جيدًا، مما يسبب الغازات والانتفاخ»، و«الخضروات في حد ذاتها غالبًا ما تكون ضارة بسبب الاستخدام الواسع للمبيدات».

not verbatim – paraphrase. Translation by the project; the Arabic wording is authoritative.

Translation

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.

Origin

Source status

Archive quote (no location given)

Attribution

Elawady (archive paraphrase; source video not given)

Origin

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

Attribution uncertainty

The archive attributes this text to Dr. Diaa in its 'د. ضياء يقول' box but gives no video reference. Transcript check (the project's research files, keyword search of 307 archive transcripts): found_close_paraphrase. The ruminant/cellulose argument is found (6-qWOj0AXhc, VsuHx9JUze0). The archive's wording ('multiple stomachs and specialised bacteria', 'gas and bloating') is a Modern Standard Arabic rendering, not his transcribed words.

Claimed mechanism

No cellulase; no rumen; cellulose acts like 'plastic' and produces gas.

Claimed health effect

Gas, bloating; vegetables unsuitable for humans.

Population concerned

Everyone

Geographic restriction by Elawady

none found

Diverging source versions

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?

Humans cannot digest cellulose, therefore greens are cattle food and harmful.

2. What is demonstrably correct?

Human enzymes do not break down cellulose; ruminants rely on microbial fermentation in the rumen; part of plant fibre passes the gut unchanged; fermentation produces gas.

3. What is wrong or exaggerated?

Non-digestibility is the defining feature of dietary fibre and the basis of its benefits: colonic bacteria ferment many fibres (and some cellulose) into short-chain fatty acids that serve as energy for colon cells and act on host physiology (Koh 2016). Vegetables are not mostly cellulose; they provide water, vitamins (folate, vitamin K, vitamin C), potassium and other nutrients that humans absorb. Highest vs lowest fibre intake is associated with 15-30% lower all-cause and cardiovascular mortality (Reynolds 2019). The analogy to rumen bloat in cattle has no counterpart in normal human digestion.

4. What remains unclear?

How much cellulose an individual ferments depends on the microbiome (see C-VEG-02).

5. Which studies support it?

None for the conclusion.

6. Which studies contradict it?

Reynolds 2019; Aune 2017 (green leafy vegetables and salads inversely associated with CVD and mortality); Koh 2016.

7. What applies to Germany and Europe?

DGE and EU guidelines recommend vegetables daily (not fetched in this review).

8. What is known about Egypt?

Molokhia, salads and leafy greens are traditional Egyptian foods; no Egyptian data suggest harm from normal intake.

9. What practical conclusion is appropriate?

Gas after vegetables is normal fermentation; fibre-rich vegetables are recommended, not contraindicated.

Assessment details

Rationale for certainty of evidence

The premise (humans lack cellulose-digesting enzymes) is correct, but the conclusion is contradicted by fibre physiology (microbial fermentation to short-chain fatty acids) and by consistent meta-analyses linking fibre and vegetable intake to lower mortality and disease (Reynolds 2019: GRADE moderate for fibre).

Source quality

Archive quote plus an explicit video passage comparing humans with cows.

Regional transferability

Applies everywhere.

Individual exceptions

People with IBS or certain bowel conditions may need to limit some fibre types individually.

Regional scope of the claim

general (biological/medical)

Last reviewed

25 October 2026 provisional

In plain language

It is true that human enzymes cannot break down cellulose, unlike the microbes in a cow's stomach. But this is exactly what makes fibre useful: bacteria in our large intestine ferment it into substances that nourish the gut lining, and fibre adds bulk to stool. Vegetables also supply vitamins and minerals that we absorb well. Large studies link higher fibre and vegetable intake with lower rates of heart disease, diabetes, bowel cancer and death.

Studies on this claim

Regional context

Germany / EU

DGE and EU guidelines recommend vegetables daily (not fetched in this review).

Egypt

Molokhia, salads and leafy greens are traditional Egyptian foods; no Egyptian data suggest harm from normal intake.

• 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 Correct premise, wrong conclusion: indigestible fibre is beneficial, not a sign that vegetables are animal food.

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. 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
2. Fruit and vegetable intake and the risk of cardiovascular disease, total cancer and all-cause mortality-a systematic review and dose-response meta-analysis of prospective studies.. Aune D et al.. Int J Epidemiol 2017 · PMID 28338764 · DOI 10.1093/ije/dyw319
3. 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
4. Cryptic diversity of cellulose-degrading gut bacteria in industrialized humans.. Moraïs S et al.. Science 2024 · PMID 38484069 · DOI 10.1126/science.adj9223