Cross-sectional studyindependent cross-checkabstract checked I-GRN-113 standard review
Some coeliac patients make antibodies against corn protein
The Prevalence of Anti-Zein Antibodies: A Comparative Study between Celiac Disease and Irritable Bowel Syndrome.
Overview
Sánchez-Vargas LA et al.. Nutrients 2021 · PMID 33671228 · DOI 10.3390/nu13020649
About a third of newly diagnosed coeliac patients had antibodies to the maize protein zein, rarely seen in others.
Does the study support the specific claim? Partly · Methodological quality: low
Plain-language summary
Study explained simply
- What did the researchers want to find out?
Check immune reactions to maize protein.
- How was the study done?
Blood antibody tests.
- How many people, animals or samples were studied?
714 people.
- What was actually found?
Anti-zein IgA common in new coeliac patients.
- How large was the observed effect?
35.1% vs 2.3%.
- What do the results mean in everyday life?
Maize proteins resemble gluten in some ways.
- What are the study's limitations?
Antibodies are not disease.
- What does it say about Elawady's specific claim?
Partly supports botanical similarity; not that maize is unsafe.
- Do the results apply to Germany and Europe?
Moderate.
- What can explicitly not be concluded from this study?
Cannot show that maize damages the gut.
Scientific in-depth review
1. Full reference
- Authors
- Sánchez-Vargas LA et al.
- Journal
- Nutrients
- Year
- 2021
- Identifier
- PMID 33671228 DOI 10.3390/nu13020649 · PMC7922782
- Verification
- verified – PubMed efetch 2026-10-26; Crossref works API 2026-10-26
- Retracted
- no
- Corrections
- none
- Extent checked
- abstract only
- Conflicts of interest and funding
No conflicts declared; CONACYT funding.
2. Research question
How common are antibodies to maize zein in coeliac disease compared with IBS and healthy controls?
3. Study design and population
- Study design
- Cross-sectional study – Cross-sectional serology study
- Population
Newly diagnosed coeliac patients, IBS patients, healthy controls
- Country
not stated in abstract (funded by the Mexican CONACYT)
- Period
not stated in abstract
- Sample size
37 coeliac, 375 IBS, 302 controls
- Inclusion and exclusion criteria
Newly diagnosed coeliac disease (16 biopsy, 21 serology)
4. Methods and endpoints
- Exposure / intervention
Diagnosis group
- Comparator
IBS; healthy controls
- Endpoints
IgA and IgG anti-zein antibodies (in-house ELISA)
- Statistical methods
Prevalence comparison; correlation
5. Actual results
- Results
IgA anti-zein prevalence: coeliac 35.1%, IBS 4.3%, controls 2.3% (p<0.0001); no IgG anti-zein in any group; IgA anti-zein correlated with anti-gliadin (r=0.34) and anti-DGP (r=0.42) in coeliac patients.
- Absolute risks
not reported
- Authors' conclusion
Higher prevalence of IgA anti-zein in newly diagnosed coeliac disease, indicating a biased immune response to gliadin-related prolamins such as zein in susceptible people.
6. Strengths
- Comparison groups
7. Weaknesses
- In-house ELISA
- Small coeliac group
- Antibodies may reflect cross-reactivity, not clinical harm
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
- Rationale
Assay validation uncertain; newly diagnosed (untreated) patients have generally leaky mucosa.
9. Assessment of the statistical interpretation
Antibody presence is not evidence that maize damages the intestine.
10. Relevance to the specific claim
The best support for the claim that maize proteins are "gluten-like": some coeliac patients form antibodies to zein. No clinical harm shown; guidelines still treat maize as safe.
11. Independent contrary findings
ESsCD recommends whole-grain maize and rice in coeliac diets.
12. Transferability to Germany and Europe
Moderate.
13. Overall methodological judgement
Weak, indirect support for a biochemical similarity only.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | low |
| Risk of bias | some concerns |
| Precision of results | low |
| Directness | indirect |
| Reproducibility | not replicated |
| Consistency with the overall evidence | mixed |
| Regional transferability | moderate |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
Whether maize harms a small subgroup of non-responsive coeliac patients.
15. Linked fact checks
- Gluten is present in all grains, including oats, rice and maize, so 'gluten-free' bread or flour is a meaningless concept. – Studies with mixed or unclear results