Zinc absorption and zinc status are reduced after Roux-en-Y gastric bypass: a randomized study using 2 supplements1–3

Abstract

Background: Micronutrient deficiencies are common in patients undergoing gastric bypass. The effect of this type of surgery on zinc absorption and zinc status is not well known. Objective: The objective was to evaluate the effects of Roux-en-Y gastric bypass (RYGBP) on zinc status and zinc absorption at dif-ferent stages after surgery. We hypothesized that zinc status would be significantly impaired after surgery and that this impairment would be less severe in subjects receiving increased supplemental zinc. We also hypothesized that zinc absorption would be lower after surgery. Design: Anthropometric and body-composition variables and die-tary and biochemical indexes of zinc status and zinc absorption were determined in 67 severe and morbidly obese women [mean (6SD) age: 36.9 6 9.8 y; BMI (in kg/m2): 45.2 6 4.7] who un-derwent RYGBP. The subjects were randomly assigned to 1 of 2 vitamin-mineral supplementation groups. Measurements were made before and 6, 12, and 18 mo after surgery. Fifty-six subjects com-pleted the 18-mo follow-up. Results: Mean plasma zinc, erythrocyte membrane alkaline phos-phatase activity, and the size of the rapidly exchangeable zinc pool decreased after RYGBP. Percentage zinc absorption decreased sig-nificantly from 32.3 % to 13.6 % at 6 mo after RYGBP and to 21 % at 18 mo after surgery. No effect of supplement type was observed. Conclusions: Zinc status is impaired after RYGBP, despite the finding that dietary plus supplemental zinc doubled recommended zinc intakes in healthy persons. Zinc absorption capacity is signifi-cantly reduced soon after RYGBP, with no major changes until 18 mo after surgery. Am J Clin Nutr doi: 10.3945/ajcn.111.018143