Laboratory / cell studyindependent cross-checkabstract only checked I-INTA-18 standard review
Is oxytocin absorbed when swallowed?
Impact of Peptide Structure on Colonic Stability and Tissue Permeability.
Overview
Taherali F et al.. Pharmaceutics 2023 · PMID 37514143 · DOI 10.3390/pharmaceutics15071956
Peptide hormones like oxytocin are broken down in the gut and poorly absorbed; that is why they are usually injected.
Does the study support the specific claim? Unclear · Methodological quality: low
Plain-language summary
Study explained simply
- What did the researchers want to find out?
Oxytocin stability in the gut
- How was the study done?
Laboratory study
- How many people, animals or samples were studied?
Oxytocin and 11 analogues
- What was actually found?
Native oxytocin is enzymatically vulnerable
- How large was the observed effect?
Up to 79% stability gain with modifications
- What do the results mean in everyday life?
Oxytocin traces in milk are unlikely to act like an injection
- What are the study's limitations?
Indirect lab data
- What does it say about Elawady's specific claim?
Weakens a consumer-harm argument
- Do the results apply to Germany and Europe?
High
- What can explicitly not be concluded from this study?
Exact absorption from milk
Scientific in-depth review
1. Full reference
- Authors
- Taherali F et al.
- Journal
- Pharmaceutics
- Year
- 2023
- Identifier
- PMID 37514143 DOI 10.3390/pharmaceutics15071956
- Verification
- verified – PubMed efetch 2026-10-25
- Retracted
- no
- Corrections
- none
- Extent checked
- abstract only
- Conflicts of interest and funding
not stated in abstract
2. Research question
How cyclisation and D-amino-acid substitution affect colonic stability and permeability of oxytocin and analogues
3. Study design and population
- Study design
- Laboratory / cell study – Laboratory study of peptide stability (human colon model) and permeability (rat colonic tissue)
- Population
Not applicable
- Country
Not stated in abstract
- Period
not stated
- Sample size
Native oxytocin and 11 analogues
- Inclusion and exclusion criteria
Not applicable
4. Methods and endpoints
- Exposure / intervention
Peptide structural modifications
- Comparator
Native oxytocin
- Endpoints
Enzymatic stability; tissue permeability
- Statistical methods
not stated in abstract
5. Actual results
- Results
Most marketed peptide drugs are given parenterally because of gastrointestinal instability and poor permeability. Native oxytocin's disulfide cyclisation gave better colonic stability than a linear derivative; specific D-amino-acid substitutions increased stability at 1.5 h by 58.2% (linear) and 79.1% (cyclic).
- Absolute risks
Not applicable
- Authors' conclusion
Strategic peptide design could enable oral delivery to the colon.
6. Strengths
- Direct study of oxytocin stability
7. Weaknesses
- In vitro/ex vivo
- Colon model, not whole-gut digestion of milk
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
Indicates that unmodified oxytocin is enzymatically vulnerable and poorly permeable; does not quantify absorption from milk.
10. Relevance to the specific claim
Plausibility that ingested oxytocin from milk has little systemic effect.
11. Independent contrary findings
No study of oxytocin absorption from milk in humans was found.
12. Transferability to Germany and Europe
High.
13. Overall methodological judgement
Indirect support for low oral bioavailability of oxytocin.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | low |
| Risk of bias | not assessable |
| Precision of results | not applicable |
| Directness | very indirect |
| Reproducibility | unknown |
| Consistency with the overall evidence | unknown |
| Regional transferability | high |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
Human data on oral oxytocin from milk.