Nutritional Consequences of Adjustable Gastric Banding and Gastric Bypass: A 1-year Prospective Study

Gastric bypass (GBP) is more efficient than adjustable gastric banding (AGB) on weight loss and comorbidities, but potentially induces more nutritional deficits. However, no study has compared the prevalence of nutritional deficiencies after these two bariatric procedures. To prospectively compare the prevalence of nutritional deficiencies after AGB and GBP. We have performed a 1-year prospective study of nutritional parameters in 70 consecutive severe obese patients, who had undergone bariatric surgery, 21 AGB and 49 GBP. After GBP, multivitamin supplements were systematically prescribed and vitamin B12 supplementation was introduced if a deficiency was observed. Patients lost more weight after GBP than after AGB (40 +/- 13 vs 16 +/- 8 kg, p < 0.001). Vitamins B1 and C and iron deficiencies were frequent before surgery but were not worsened by GBP. AGB only induced a slight decrease of vitamin B1 at 1 year, whereas GBP induced significant decreases of vitamins B12 and E, serum prealbumin, and creatinine concentrations, with only minor clinical consequences. Anemia was observed in 10% of the patients after bariatric surgery. Hemoglobin concentration was not correlated to vitamin B12 or folate concentrations but was related to iron status. Risk of iron deficiency anemia was better assessed by transferrin saturation than by serum ferritin concentration in this obese population. Severe nutritional deficits can be avoided after bariatric surgery if patients are systematically supplemented with multivitamin and carefully monitored. However, specific care is required to avoid iron and vitamin B12 deficiencies, anemia, and protein malnutrition.