Meta-analysisindependent cross-checkabstract checked★ key study I-EGG-113 in-depth review
Eating eggs does not raise TMAO in blood tests
Effect of egg consumption on circulating choline, betaine, and trimethylamine n-oxide in adults: a systematic review and meta-analysis of randomized controlled trials.
Overview
Aryaeian N et al.. Nutr J 2025 · PMID 41146117 · DOI 10.1186/s12937-025-01227-0
Pooled trials found no change in TMAO after egg consumption (WMD -0.08 umol/L).
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?
Test whether eggs raise TMAO.
- How was the study done?
Meta-analysis of randomized trials.
- How many people, animals or samples were studied?
5-6 RCTs.
- What was actually found?
No effect on TMAO, choline or betaine.
- How large was the observed effect?
TMAO WMD -0.08 (-0.47 to 0.32) umol/L.
- What do the results mean in everyday life?
The 'eggs -> TMAO -> heart attack' chain breaks at its first step.
- What are the study's limitations?
Few small trials.
- What does it say about Elawady's specific claim?
Contradicts it.
- Do the results apply to Germany and Europe?
Universal.
- What can explicitly not be concluded from this study?
It cannot settle whether TMAO itself harms the heart.
Scientific in-depth review
1. Full reference
- Authors
- Aryaeian N et al.
- Journal
- Nutr J
- Year
- 2025
- Identifier
- PMID 41146117 DOI 10.1186/s12937-025-01227-0
- 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
Authors declare no competing interests.
2. Research question
Does egg consumption change circulating choline, betaine and TMAO in adults?
3. Study design and population
- Study design
- Meta-analysis – Systematic review and meta-analysis of RCTs with NutriGRADE
- Population
Adults in 6 RCTs (5 for TMAO)
- Country
Multinational
- Period
not stated in abstract
- Sample size
6 RCTs
- Inclusion and exclusion criteria
not detailed in abstract
4. Methods and endpoints
- Exposure / intervention
Egg consumption
- Comparator
Control diets
- Endpoints
Plasma choline, betaine, TMAO
- Statistical methods
Random-effects WMD; subgroup analyses; meta-regression; Egger/Begg tests; trim-and-fill
5. Actual results
- Results
TMAO WMD -0.08 umol/L (95% CI -0.47 to 0.32; p = 0.692; I2 = 23%); choline WMD 0.10 (-0.92 to 1.12); betaine WMD 0.21 (-8.50 to 8.92). No publication bias for TMAO. NutriGRADE moderate certainty.
- Absolute risks
not reported
- Authors' conclusion
No clear effect of egg consumption on circulating choline, betaine or TMAO could be demonstrated.
6. Strengths
- Only RCTs
- Low heterogeneity for TMAO
- Publication bias assessed
7. Weaknesses
- Few, small, short trials
8. Risk of bias
- Orienting tool
- AMSTAR 2
- Type of assessment
- simplified assessment (abstract only)
- Full formal assessment
- no
- Overall risk of bias
- some concerns
- Rationale
Small number of trials; simplified judgement.
9. Assessment of the statistical interpretation
Even the upper CI (+0.32 umol/L) implies a negligible change in risk under the TMAO-mortality dose-response (stats/C-EGG-05_tmao.py).
10. Relevance to the specific claim
Directly tests the first link of the archive's chain (eggs -> TMAO): no effect in RCTs.
11. Independent contrary findings
Acute post-meal TMAO rises after eggs plus labelled phosphatidylcholine (A-EGG-13).
12. Transferability to Germany and Europe
Universal biology.
13. Overall methodological judgement
Key counter-evidence: eggs do not raise circulating TMAO in trials.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | moderate |
| Risk of bias | some concerns |
| Precision of results | moderate |
| 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
Long-term trials; people with kidney disease.
15. Linked fact checks
- Egg-yolk phosphatidylcholine is converted by gut bacteria into TMAO, and therefore eggs raise the risk of major cardiovascular events (about 2.5-fold). – Studies contradicting or limiting the claim