Bariatric surgery in adolescents, particularly Roux-en-Y gastric bypass (RYGB) was associated with an increasing prevalence of several nutritional deficiencies over 5 years, a study by the Teen Longitudinal Assessment of Bariatric Surgery (Teen-LABS) consortium found.

Stavra Xanthakos, MD, MS, of Cincinnati Children's Hospital Medical Center, and colleagues reported that 5 years out, 59% of RYGB and 27% of vertical gastric sleeve (VSG) recipients had two or more nutritional deficiencies. After RYGB, serum concentrations of vitamin B12 significantly decreased, whereas serum levels of transferrin and parathyroid hormone increased.

As shown in the team's study online in Clinical Gastroenterology and Hepatology, ferritin levels decreased significantly after both RYGB and VSG. Hypoferritinemia was present in 2.5% of patients before RYGB and 71% at 5 years (P<0.0001), and in 11% of patients before VSG and 45% at 5 years after (P=0.002).

"Our results now provide critical evidence that VSG does in fact carry significantly lower nutritional risk than RYGB, but can still worsen iron status," the authors wrote.

No significant changes in serum folate or vitamins A, B1, or D emerged between baseline and 5 years after either procedure. Risk factors associated with specific deficiencies included surgery type, female sex, black race, supplementation intake, weight regain, and pregnancy.

"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 researchers said.

They explained that while bariatric surgery is an increasingly accepted treatment for severe obesity in young people, post-surgical nutritional deficiencies have been estimated largely from adult cohorts. "Yet, lower adherence to supplementation and anticipated longer lifespan with altered gastrointestinal physiology may increase risk of adverse nutritional outcomes in these youth."

Earlier this year, the Teen-LABS researchers reported that while weight loss was similar in teens to that in adults at 26% and 29%, respectively, adolescents had a significantly higher rate of intra-abdominal reoperations within 5 years of initial surgery.

Study Details

Patients were enrolled in five tertiary-care centers from March 2007 through February 2012. The newly published final analysis included 226 participants (161 who had RYGB and 65 who had VSG). Participants were 75% female and 72% white, with a mean age of 16.5 years and a mean body mass index (BMI) of 52.7 at surgery. Mean BMI decreased by 23% at 5 years and did not differ significantly between procedures.

At baseline and then annually for 5 years, the study measured serum levels of vitamins A, D, B1, and B12; ferritin; red blood cell folate; and parathyroid hormone. General linear mixed models were used to examine changes over time and identify factors associated with nutritional deficiencies.

The researchers said that, not surprisingly, greater multivitamin intake was associated with higher ferritin, vitamin B12, folate, vitamin A, and 25-hydroxyvitamin D levels and reduced odds of vitamin D deficiency; vitamin D and calcium supplementation were not associated with parathyroid hormone levels.

The lower but still appreciable nutritional risk of VSG underscores the need to monitor recipients of endoscopic sleeve and other bariatric procedures, as their use is likely to increase, the authors stated. VSG is now the predominant bariatric surgery in adolescents and adults in view of its limited anatomical alteration, lower operative risk, and presumed lower risk of nutritional deficits.

Asked for her perspective, Elizabeth Parks Prout, MD, MSCE, of Children's Hospital of Philadelphia, who was not involved with the research, called the study "a wonderful follow-up, as the group's prior publication on nutrition deficiencies after surgery did not include VSG."

She added that while both procedures are safe and effective for treating obesity and serious comorbidities such as type 2 diabetes, obstructive sleep apnea, and high blood pressure, both surgeries do have complications.

"And it is a natural tendency for adolescents to decrease medication use during adolescence, so this study emphasizes the need for life-long follow-up," Prout said. "After the 2-year visit, patients should have vitamin and mineral levels checked at least yearly. Adolescents with deficiencies prior to surgery are more likely to continue to have those deficiencies."

She added that surprisingly, the study did not find B1 deficiencies, which have been noted in adults after both surgeries. For example, a 2018 study by Tang and colleagues found a "troubling" higher risk of B1 deficiency in African Americans in the first 3 years.

"This study reinforces the pediatric follow-up and nutrition recommendations of the American Society for Metabolic and Bariatric Surgery published in 2018," Prout said.

Study limitations, Xanthakos and co-authors noted, included some missing data and the limited number of nutritional measures available, which precluded full characterization of iron and vitamin B12 nutriture. In addition, copper, zinc, and vitamin E were not assessed, and the self-reported supplement intake by participants was likely to entail appreciable error, possibly biasing findings towards the null. Data on dietary intake and non-recommended supplements were also lacking.