Medical complications of bariatric surgery: focus on malabsorption and dumping syndrome.

Gastroenterologists increasingly see patients with symptoms after bariatric surgery. A number of gastrointestinal or extra-gastrointestinal symptoms should raise the suspicion of malabsorption or dumping syndrome. Little is known about long-term consequences of disordered intestinal anatomy and physiology resulting from bariatric surgical procedures. The latency phase of clinical problems is unknown, but may potentially be long, and postoperative courses over many decades have to be considered regarding the consequences of surgical alterations of gastrointestinal structure and function. Long-term nutritional requirements in patients with bariatric procedures are incompletely understood. This review focuses on the pathophysiology of long-limb Roux-en-Y gastric bypass (RYGB) because it has become the most common bariatric procedure in many parts of the world. Although several potential mechanisms for nutritional deficiencies after RYGB like deficiency of dietary intake, lack of gastric secretions, exclusion of proximal duodenum and jejunum, or asynergia between food bolus and biliopancreatic secretions have been postulated, it was only very recently that in-depth studies have been carried out to measure the extent to which the long-limb RYGB causes malabsorption. In order to improve care for these patients, specialists who are trained in understanding pathophysiological changes in digestion and absorption after bariatric surgery and who recognize and treat clinical symptoms and nutritional deficits after bariatric surgery are needed. In addition, clinical researchers should take advantage of the experimental setups provided by standardized surgical procedures, and scientific societies should design courses and scientific meetings which combine the expertise in gastroenterology, surgery and nutrition.