From the AGA Journals

Adolescents at risk of nutritional deficiencies after bariatric surgery

The prevalence of obesity in adolescents has ballooned to about 20% of children aged 12-19 years. Prevention with diet and exercise remains the cornerstone of obesity policy in the pediatric population. Once patients develop obesity, however, bariatric surgery increasingly is being recommended as a treatment to achieve durable weight loss. Multiple large studies in adults have shown strong evidence of the efficacy of bariatric surgery; comparable data in pediatric patients has been sparse.

Dr. Wasif Abidi is affiliated with Baylor St. Luke's Hospital in Houston

Dr. Wasif Abidi

The Teen-Longitudinal Assessment of Bariatric Surgery (Teen-LABS), a multicenter prospective consortium, was established in 2007 to better study outcomes of bariatric surgery in adolescents. Early data showed much-needed strong evidence of the safety and efficacy of metabolic and bariatric surgery in this population. The positive effects of these surgeries, however, needed to be weighed against the risk of nutritional deficiencies in this vulnerable population given their young age and poor compliance with vitamin supplementation. Early retrospective data suggested adolescents may be at higher risk of deficiencies.

The current study by Xanthakos et al. reports on 5-year prospective data from Teen-LABS specifically addressing the nutritional status of adolescents after Roux-en-Y gastric bypass and sleeve gastrectomy. Their data show deficiency only in iron and vitamin B12 levels after gastric bypass. More importantly, vertical sleeve gastrectomy, now the most common procedure, results in decreased risk of nutritional deficiencies compared with gastric bypass. These data add to the reassurance that surgical treatment in the adolescent population is overall safe and should be considered strongly after appropriate counseling.

Wasif M. Abidi, MD, PhD, is an assistant professor of medicine, section of gastroenterology and hepatology, Baylor College of Medicine, Houston. He has received research support from GI Dynamics.



Adolescents who undergo metabolic bariatric surgery may require long-term nutrient monitoring and supplementation to prevent nutritional deficiencies, according to investigators.

In a 5-year prospective study, more than a quarter of the participants who underwent vertical sleeve gastrectomy (VSG) developed two or more nutritional deficiencies, reported lead author Stavra A. Xanthakos, MD, of the Cincinnati Children’s Hospital Medical Center, and colleagues.

“Although prevalence of nutritional deficiencies has been estimated largely from adult cohorts, bariatric surgery is an increasingly accepted treatment for severe obesity in youth,” the investigators wrote in Clinical Gastroenterology and Hepatology. “Yet, lower adherence to supplementation and anticipated longer lifespan with altered gastrointestinal physiology may increase risk of adverse nutritional outcomes in these youth.”

Previous research has suggested that teens may be at higher risk for nutritional deficiencies, but these studies were largely retrospective, or when prospective, lacked sufficient long-term follow-up, analysis of comprehensive patient factors, or inclusion of VSG, which is now the predominant technique in the field, the investigators noted.

“Our study is the first to assess comparative nutritional outcomes in adolescents after both VSG and gastric bypass,” they wrote.

The study involved 226 participants aged 13-19 years who underwent either Roux-en-Y gastric bypass (n = 161) or VSG (n = 67) at five tertiary-care centers in the United States during 2007-2012.

Six months after surgery, at 12 months, and on an annual basis thereafter, the investigators gathered clinical data and measured participant serum levels of ferritin; transferrin; albumin; parathyroid hormone; C-reactive protein; and vitamins A, D, B1, B12, and folate. Analyses also included sex, age, ethnicity, race, household demographics, weight, height, comorbidities, and body mass index (BMI).

The majority of participants were female (75%) and white (72%). At baseline, mean BMI and age were 52.7 kg/m2 and 16.5 years, respectively. After 5 years, mean body mass index decreased 23% without a significant difference between procedures.

Generally, nutritional deficiencies occurred earlier and were more common after gastric bypass, although both procedures were ultimately associated with increased risks.

In the gastric bypass group, 59% of participants had two or more nutritional deficiencies at 5 years, and 19% had three more deficiencies, which represented increased rates of fivefold and sixfold, respectively, which the investigators described as “striking.” In the VSG group, 27% of patients had two or more nutritional deficiencies at 5 years; while this fourfold increase was not statistically significant, the investigators suggested that it indicated “a lower, but not negligible, nutritional risk.”

Hypoferritinemia was particularly common in both groups, with rates at year 5 of 71% and 45% among patients who underwent gastric bypass and VSG, respectively.

“Our results now provide critical evidence that VSG does in fact carry significantly lower nutritional risk than Roux-en-Y gastric bypass, but can still worsen iron status,” the investigators wrote.

The investigators also highlighted a nonsignificant increase in the incidence of vitamin B12 deficiency among patients who underwent gastric bypass, with rates increasing from 0.6% at baseline to 11.5% at 5 years.

“Vitamin B12 status likewise worsened disproportionately after [gastric bypass], despite similar trajectories of weight loss after VSG,” the investigators wrote. “This suggests that the differential risk is caused by anatomic and physiological differences between procedures, rather than weight loss alone.”

Beyond surgery type, risk factors for nutritional deficiency included inadequate supplement intake, pregnancy, weight regain, and black race.

“Our findings underscore the importance of long-term nutritional monitoring in adolescents after bariatric surgery and the need to examine impact on health outcomes and quality of life as these youth advance into adulthood, including systematic assessment of anemia and bone health,” the investigators concluded.

The study was funded by the National Institute of Diabetes and Digestive and Kidney Diseases and the National Center for Advancing Translational Sciences of the National Institutes of Health. Dr. Courcoulas reported grant support from Allurion.

SOURCE: Xanthakos SA et al. Clin Gastro Hepatol. 2019 Nov 6. doi: 10.1016/j.cgh.2019.10.048.

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