Oral Vitamin B 12 Supplementation After Roux-en-Y Gastric Bypass: a Systematic Review

Many respectable guidelines recommend lifelong vitamin B 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 B is adequate for prophylactic purposes in RYGB patients and the appropriate dosages needed for this purpose if it is. We examined the PubMed database for all English language articles examining various doses of oral vitamin B supplementation after proximal RYGB in adult patients. The search revealed 19 such articles. The data suggest that oral vitamin B 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 B 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 B daily lead to an increase in B levels and are sufficient for the prevention of its deficiency in most RYGB patients. The review finds that oral supplementation doses of ≤ 15 μg vitamin B daily are inadequate for prophylaxis of vitamin B deficiency in adult RYGB patients but doses of 1000 μg vitamin B daily might be adequate. Future studies need to examine this and even higher oral doses for vitamin B supplementation for patients undergoing RYGB.