• Kamal K Mahawar, Alastair Reid, Yitka Graham, Lindes Callejas-Diaz, Chetan Parmar, William Rj Carr, Neil Jennings, Rishi Singhal, and Peter K Small.
• Bariatric Unit, Department of General Surgery, Sunderland Royal Hospital, Sunderland, SR4 7TP, UK. kamal_mahawar@hotmail.com.
• Obes Surg. 2018 Jul 1; 28 (7): 1916-1923.

BackgroundMany respectable guidelines recommend lifelong vitamin B12 injections for Roux-en-Y gastric bypass (RYGB) patients in the absence of lack of consensus on the efficacy of oral route of prophylaxis and the appropriate doses needed for this purpose. The purpose of this review was to examine the published English language scientific literature in accordance with PRISMA principles to find out if orally given vitamin B12 is adequate for prophylactic purposes in RYGB patients and the appropriate dosages needed for this purpose if it is.MethodsWe examined the PubMed database for all English language articles examining various doses of oral vitamin B12 supplementation after proximal RYGB in adult patients. The search revealed 19 such articles.ResultsThe data suggest that oral vitamin B12 supplementation doses of ≤ 15 μg daily are insufficient to prevent deficiency in RYGB patients. Higher supplementation doses show better results and it appears that a dose of 600.0 μg vitamin B12 daily is superior to 350.0 μg daily suggesting an incremental dose-response curve. It further appears that supplementation doses of 1000.0 μg vitamin B12 daily lead to an increase in B12 levels and are sufficient for the prevention of its deficiency in most RYGB patients.ConclusionThe review finds that oral supplementation doses of ≤ 15 μg vitamin B12 daily are inadequate for prophylaxis of vitamin B12 deficiency in adult RYGB patients but doses of 1000 μg vitamin B12 daily might be adequate. Future studies need to examine this and even higher oral doses for vitamin B12 supplementation for patients undergoing RYGB.

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