Meta-analysisindependent cross-checkabstract checked★ key study I-BAR-149 in-depth review
Meta-analysis: vitamin shortages 5-17 years after surgery
Long-term prevalence of vitamin deficiencies after bariatric surgery: a meta-analysis.
Overview
Chen et al.. Langenbecks Arch Surg 2024 · PMID 39030449 · DOI 10.1007/s00423-024-03422-9
Years after surgery, about 1 in 3 people lacked vitamin D and about 1 in 12 lacked vitamin B12.
Does the study support the specific claim? Yes · Methodological quality: moderate
Plain-language summary
Study explained simply
- What did the researchers want to find out?
Long-term vitamin deficiencies
- How was the study done?
Meta-analysis
- How many people, animals or samples were studied?
54 studies
- What was actually found?
Vitamin D 35.8%, B12 8.5%
- How large was the observed effect?
Proportions
- What do the results mean in everyday life?
Lifelong vitamin checks are needed
- What are the study's limitations?
Heterogeneous
- What does it say about Elawady's specific claim?
Supports the claim in substance, not universality
- Do the results apply to Germany and Europe?
Applicable
- What can explicitly not be concluded from this study?
Comparison with non-operated people
Scientific in-depth review
1. Full reference
- Authors
- Chen et al.
- Journal
- Langenbecks Arch Surg
- Year
- 2024
- Identifier
- PMID 39030449 DOI 10.1007/s00423-024-03422-9
- Verification
- verified – PubMed efetch 2026-10-26 + Crossref API
- Retracted
- no
- Corrections
- none
- Extent checked
- abstract only
- Conflicts of interest and funding
Grants listed: Guangdong Medical Research Foundation, the Fundamental Research Funds for the Central Universities, the Funding by Science and Technology Projects in Guangzhou, the Guangdong Province general university youth innovative talent project, the scientific research project of the Chinese medicine bureau in Guangdong Province
2. Research question
What is the long-term (>=5 y) prevalence of vitamin deficiencies after bariatric surgery?
3. Study design and population
- Study design
- Meta-analysis – Systematic review and meta-analysis of studies with >=5 y follow-up
- Population
Patients after bariatric surgery (RYGB, SG, BPD-DS and others)
- Country
Multinational
- Period
Search to June 2023
- Sample size
54 articles; follow-up 5-17 years
- Inclusion and exclusion criteria
Clinical studies with >=5 y follow-up
4. Methods and endpoints
- Exposure / intervention
Bariatric surgery
- Comparator
Between procedures and regions
- Endpoints
Vitamin A, B12, D, E, K, folate deficiency
- Statistical methods
Pooled prevalence; subgroup and meta-regression analyses
5. Actual results
- Results
Long-term deficiency prevalence: vitamin D 35.8%, vitamin E 16.5%, vitamin A 13.4%, vitamin K 9.6%, vitamin B12 8.5%. Vitamin A and folate deficiency increased with follow-up time. RYGB had more B12 deficiency than SG and BPD-DS. Europe: vitamin A deficiency 25.8% vs 0.8% in America.
- Absolute risks
Vitamin D deficiency in about 1 in 3, B12 deficiency in about 1 in 12 long-term.
- Authors' conclusion
High prevalence of long-term vitamin deficiencies, varying by region, procedure and follow-up; targeted supplementation programmes are needed.
6. Strengths
- Long-term studies only
- Large number of studies
7. Weaknesses
- Heterogeneous definitions and supplementation
- Preoperative prevalence not subtracted
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
Abstract only.
9. Assessment of the statistical interpretation
Prevalences without non-surgical comparator; vitamin D deficiency is also common in people with obesity without surgery.
10. Relevance to the specific claim
Shows that vitamin deficiencies persist in a substantial minority for 5-17 years - supports the "long-term" part of the claim, while showing it is not universal.
11. Independent contrary findings
Deficiencies also exist before surgery.
12. Transferability to Germany and Europe
Includes European data.
13. Overall methodological judgement
Moderate evidence supporting long-term deficiency risk.
| 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
Effect of adherence.
15. Linked fact checks
- Bariatric surgery causes lifelong deficiencies of iron, B12, vitamin D, calcium and protein, requiring lifelong supplements. – Studies supporting the claim