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Improving Bariatric Patient Aftercare Outcome by Improved Detection of a Functional Vitamin B12 Deficiency



Vitamin B12 deficiency is common after bariatric surgery. Vitamin B12 is a poor predictor of functional vitamin B12 status, since deficiencies might even occur within the reference limits. Therefore, vitamin B12 deficiencies with serum vitamin B12 levels are between 140 and 200 pmol/L remain undetected. Methylmalonic acid (MMA), however, will detect these deficiencies as accumulates due to functional intracellular vitamin B12 deficiencies. MMA is a relative expensive analysis and is therefore not generally available. To lower the costs, we only request MMA when vitamin B12 levels are between these levels. As a result, more biochemical deficiencies are found. However, it was not known whether bariatric patients with vitamin B12 levels between 140 and 200 pmol/L would benefit from supplementation.


Bariatric patients with vitamin B12 levels between 140 and 200 pmol/L with (n = 45) and without (n = 45) intramuscular hydroxocobalamin injections were compared.


Treated patients showed a significant increase of vitamin B12 levels (P < 0.001) and a significant decrease in MMA levels (P < 0.001). Biochemical improvement occurs in both patients with and without clinical symptoms. The control group showed a significant increase of MMA levels (P < 0.001). To examine whether biochemical benefits of vitamin B12 supplementation are correlated with clinical improvement, patient records were checked for complaints. Complaints were disappeared after treatment, while no improvement was seen in untreated patients.


This study shows that all bariatric patients with vitamin B12 levels between 140 and 200 pmol/L benefit clinical and biochemical from vitamin B12 supplementation, regardless the MMA levels.

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Correspondence to H. J. M. Smelt.

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Conflict of Interest

J.F. Smulders report educational grants from Covidien and Fitforme and S.W. Nienhuijs report an educational grant from Covidien outside the submitted work. A.K. Boer, M. Said, and H.J.M. Smelt have nothing to disclose.

Ethical Approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

The Institutional Review Board of the Catharina Hospital Eindhoven approved this study and the study was performed according to the Declaration of Helsinki.

Informed Consent

Informed consent was obtained from all individual participants included in the study.

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Smelt, H.J.M., Smulders, J.F., Said, M. et al. Improving Bariatric Patient Aftercare Outcome by Improved Detection of a Functional Vitamin B12 Deficiency. OBES SURG 26, 1500–1504 (2016).

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