Cobalamin absorption and hematologic status after two types of gastric surgery for obesity

A series of morbidly obese patients was treated surgically with a gastric bypass, and a subsequent series received a vertical banded gastroplasty. To compare some of the nutritional effects of these two procedures we measured serum vitamin B 12 levels, absorption of food vitamin B 12 , frequency of microcytosis of erythrocytes, and frequency of anemia at one or more years after surgery. Patients with a gastric bypass showed greater weight loss, a greater frequency of microcytosis and anemia, more frequent subnormal serum levels of vitamin B 12 , and impressive failure to absorb food vitamin B 12 . Boiling the food containing vitamin B 12 led to increased absorption. © 1993 Wiley‐Liss, Inc.