Bariatric surgery is now recognized as a procedure of choice for the treatment of morbid obesity, resulting in long-term effectiveness on weight loss and comorbidities. The two types of procedures, most often performed in Europe, are adjustable gastric banding (AGB), a purely restrictive reversible procedure, and gastric bypass (GBP), an irreversible procedure, which associates restriction and mild malabsorption. Longitudinal sleeve gastrectomy (LSG) is another bariatric procedure which tends to develop quickly. More recent, this technique is recognized in France by the High Authority of Health since 2008, consisting of fundus and greater curvature resection, removing 75 % the gastric volume, leaving a narrow gastric tube or "sleeve".
Although malabsorption does not occur in most bariatric procedures, micronutrient deficiencies are possible. GBP is known to induce nutritional and vitamin deficiencies concerning iron, calcium, vitamins B12, B9, D and proteins. Restrictive procedures have minor effects on normal physiological digestive processes but could lead to vitamin deficiency secondary to decreased nutrient intake and a tendency towards avoidance of certain types of food due to intolerance. Studies of nutritional complications of bariatric surgery concern essentially AGB, GBP and vertical banded gastroplasty (VBG) which is no longer performed in France. The nutritional impact of LSG remains to be evaluated. To date, data concerning evaluation of nutritional status from patients who underwent LSG are almost non-existent. Considering this type of surgical procedure, the investigators expect to observe essentially a deficiency in vitamin B12 and iron. Indeed, defined as a purely restrictive intervention, LSG consists of gastric fundus resection which is the site of intrinsic factor production, itself necessary for vitamin B12 absorption. Moreover, decrease of hydrochloric acid production and potential vomiting caused by gastric resection can alter iron absorption.
In view of the increasing popularity of this surgical technique, assessment of the nutritional consequences of longitudinal sleeve gastrectomy seems to be necessary.