Monitoring for micronutrient deficiency after bariatric surgery-what is the risk?

backgroundBariatric surgery may increase the risk of micronutrient deficiencies; however, confounders including preoperative deficiency, supplementation and inflammation are rarely considered.

objectiveTo examine the impact of bariatric surgeries, supplementation and inflammation on micronutrient deficiency.

settingTwo public hospitals, Australia.

methodsParticipants were recruited to an observational study monitoring biochemical micronutrient outcomes, supplementation dose, inflammation and glycaemic control, pre-operatively and at 1-3, 6 and 12 months after gastric bypass (GB; Roux-en-Y Gastric Bypass and Single Anastomosis Gastric Bypass; N = 66) or sleeve gastrectomy (SG; N = 144). Participant retention at 12 months was 81%.

resultsPre-operative micronutrient deficiency was common, for vitamin D (29-30%), iron (13-22%) and selenium (39% GB cohort). Supplement intake increased after surgery; however, dose was <50% of target for most nutrients. After SG, folate was vulnerable to deficiency at 6 months (OR 13 [95% CI 2, 84]; p = 0.007), with folic acid supplementation being independently associated with reduced risk. Within 1-3 months of GB, three nutrients had higher deficiency rates compared to pre-operative levels; vitamin B1 (21% vs. 6%, p < 0.01), vitamin A (21% vs. 3%, p < 0.01) and selenium (59% vs. 39%, p < 0.05). Vitamin B1 deficiency was independently associated with surgery and inflammation, selenium deficiency with improved glycaemic control after surgery and inflammation, whilst vitamin A deficiency was associated with inflammation only.

conclusionIn the setting of prophylactic post-surgical micronutrient prescription, few nutrients are at risk of de novo deficiency. Although micronutrient supplementation and monitoring remains important, rationalising high-frequency biochemical testing protocols in the first year after surgery may be warranted.