Vitamin B12 deficiency accounts up to 23-64% bariatric surgery. The investigators purpose is to evaluate the most effective treatment for vitamin B12 deficiency in patients who underwent a Roux-en-Y gastric bypass.~Daily oral use of vitamin B12 tablets are may be as effective as vitamin B12 injections.
The purpose of this study is to evaluate the most effective treatment for patients who underwent a Roux-en-Y gastric bypass and developed postoperatively a vitamin B12 deficiency.