Vitamin B₁₂ Deficiency After Gastric Bypass Surgery for Obesity

G A S T R I C BYPASS SURGERY for obesity is a popular and partially effective operation. There are few studies of changes in chemistry after this operation. Wernicke-Kor-sakoff encephalopathy was seen in two patients at 3 months after bypass surgery (1). In one patient megalo-blastic anemia appeared 6 years after surgery (2). Serum vitamin B12 was below normal in 26 % of 69 patients (3). We are not aware of studies of vitamin B12 absorption or of the effect of oral supplementation in patients who have had bypass surgery. After a low serum vitamin B12 level was found in several patients, this study was done. Using the technique of Alden (4), two surgeons did all by-pass procedures in one community hospital. All patients report-ed here were studied 1 year or more after surgery. Serum vitamin B12 levels were determined in 93 patients after