Cross-sectional studyindependent cross-checkabstract checked I-BAR-146 standard review
Small US study: vitamins in patients who take their supplements
Postoperative micronutrient changes in bariatric surgery patients compliant with nutritional supplementation.
Overview
Sandhu et al.. Surg Endosc 2023 · PMID 37775602 · DOI 10.1007/s00464-023-10421-2
Patients who took their supplements did not show worse vitamin or mineral levels after surgery.
Does the study support the specific claim? No · Methodological quality: very low
Plain-language summary
Study explained simply
- What did the researchers want to find out?
Micronutrients with adherence
- How was the study done?
Cross-sectional
- How many people, animals or samples were studied?
~65
- What was actually found?
No worsening except B12 changes (mostly high)
- How large was the observed effect?
not applicable
- What do the results mean in everyday life?
Supplements work when taken
- What are the study's limitations?
Very small
- What does it say about Elawady's specific claim?
Limits "lifelong deficiency"
- Do the results apply to Germany and Europe?
Applicable
- What can explicitly not be concluded from this study?
Generalisation
Scientific in-depth review
1. Full reference
- Authors
- Sandhu et al.
- Journal
- Surg Endosc
- Year
- 2023
- Identifier
- PMID 37775602 DOI 10.1007/s00464-023-10421-2
- Verification
- verified – PubMed efetch 2026-10-26 + Crossref API
- Retracted
- no
- Corrections
- none
- Extent checked
- abstract only
- Conflicts of interest and funding
not stated in abstract
2. Research question
Do patients compliant with supplementation develop micronutrient deficiencies after RYGB or VSG?
3. Study design and population
- Study design
- Cross-sectional study – Cross-sectional adherence survey with retrospective laboratory comparison
- Population
Consecutive adults after RYGB or VSG who reported supplement adherence
- Country
USA
- Period
not stated in abstract
- Sample size
about 65 (laboratory comparisons)
- Inclusion and exclusion criteria
Patients >=18 y after RYGB or VSG
4. Methods and endpoints
- Exposure / intervention
Bariatric surgery with supplement adherence
- Comparator
Preoperative values; RYGB vs VSG
- Endpoints
Vitamins, minerals, iron studies
- Statistical methods
Pre-post comparisons
5. Actual results
- Results
No significant pre-post differences for any marker except vitamin B12 (normal 85.0% pre vs 61.5% post); 80% of abnormal B12 values were elevated. No differences between RYGB and VSG.
- Absolute risks
not applicable
- Authors' conclusion
Compliant patients did not have worsened micronutrient deficiencies; no difference between techniques.
6. Strengths
- Focus on adherent patients
7. Weaknesses
- Very small, retrospective
- Self-reported adherence
- Selection bias
8. Risk of bias
- Orienting tool
- none applicable
- Type of assessment
- simplified assessment (abstract only)
- Full formal assessment
- no
- Overall risk of bias
- high
- Rationale
Small, uncontrolled.
9. Assessment of the statistical interpretation
Underpowered.
10. Relevance to the specific claim
Weak evidence that deficiencies are largely preventable with adherence - limits "lifelong deficiency" wording.
11. Independent contrary findings
Larger studies show deficiencies despite supplementation (I-BAR-120).
12. Transferability to Germany and Europe
US data.
13. Overall methodological judgement
Low-quality supporting evidence for preventability.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | very low |
| Risk of bias | high |
| Precision of results | low |
| Directness | direct |
| Reproducibility | unknown |
| Consistency with the overall evidence | mixed |
| Regional transferability | moderate |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
Long-term adherent cohorts.
15. Linked fact checks
- Bariatric surgery causes lifelong deficiencies of iron, B12, vitamin D, calcium and protein, requiring lifelong supplements. – Studies contradicting or limiting the claim