 The distal part of the small intestine is then connected to the pouch, bypassing the duodenum and jejunum.In around 2% of patients there is severe malabsorption and nutritional deficiency that requires restoration of the normal absorption.The malabsorptive effect of BPD is so potent that, as in most restrictive procedures, those who undergo the procedure must take vitamin and dietary minerals above and beyond that of the normal population.