“Thank you for publishing this report of Wernicke encephalopathy after gastric bypass surgery. Although Wernicke encephalopathy was not initially suspected in the patient described, the diagnosis seems likely in retrospect. This illustrates that it is important to make all clinicians involved in the care of bariatric surgery patients alert to thiamin deficiency as a rare, but important possible complication of bariatric surgery. Further publishing of case reports on this topic is one of several ways to spread this knowledge. Among patients that have developed Wernicke encephalopathy after bariatric surgery, the complication has occurred within 6 months of surgery in 94% of cases. These patients may thus still be frankly obese when presenting with symptoms of nutritional derangement. Diagnosing Wernicke encephalopathy in a seemingly over-nourished patient may represent a particular diagnostic challenge to physicians not familiar with this potential complication of weight-loss operations. As outlined, it is important for clinicians to note that nearly all cases of Wernicke encephalopathy have occurred in patients with persistent vomiting. Another recognized risk factor is intravenous glucose administration (Aasheim ET, Ann Surg 2008). The authors are also correct in pointing out that prospective studies are needed to determine the optimal protocols for thiamin supplementation. Interestingly, a recent study showed that duodenal switch patients may be at greater risk of thiamin deficiency during the first postoperative months, as compared with gastric bypass patients (Aasheim ET et al, Am J Clin Nutr 2009). The implications of this finding for thiamin supplementation in patients undergoing different bariatric procedures remains to be elucidated in future research.”