Effects of Metabolic Bariatric Surgery On Micronutrient Status in Chinese Patients With Obesity: A 12-month Follow-up...

Trace elements and vitamin deficiencies are a major issue following metabolic bariatric surgery (MBS), although these conditions are often already present before the operation.

To evaluate changes in trace element and vitamin status in Chinese patients undergoing MBS.

This single-center retrospective cohort study included 194 patients (mean age 30.9 years (range 18-65) years, body mass index (BMI) ≥ 27.5 kg/m² with complications or > 30 kg/m²) who underwent laparoscopic sleeve gastrectomy (LSG) or laparoscopic Roux-en-Y gastric bypass (LRYGB) in our hospital from April 2023 to October 2025. All patients were followed up 12 months after the operation, and their physical indices and serum micronutrients were evaluated.

The preoperative prevalence of 25- hydroxyvitamin D and zinc deficiency exceeded 70%, affecting 75.42% (n = 135) and 85.43% (n = 129) of patients, respectively. One year after the operation, patients' BMI decreased significantly, with the median BMI dropping from 38.10 kg/m² preoperatively to 26.00 kg/m². Levels of copper, vitamin B6, and vitamin B12 decreased significantly, whereas levels of folate, 25-hydroxyvitamin D, and inorganic phosphorus increased significantly. Comparing the two operations, the increases in serum phosphorus and zinc were greater in the LSG group than in the LRYGB group. The increase of folate (6.57 ng/mL) and the decrease of vitamin B12 (-136.69 pg/mL) in the LRYGB group were significantly higher than those in the LSG group (folate: 1.40 ng/mL; vitamin B12: -13.80 pg/mL). Correlation analysis showed that greater BMI reduction was associated with larger decreases in vitamin B12 levels.

As an effective treatment for obesity, MBS reduces body weight while inducing characteristic micronutrient alterations. Notably, LRYGB has a significantly more adverse effect on vitamin B12 metabolism compared to LSG.