Prevalence of Nutritional Deficiencies in Post-Bariatric Surgery Patients: A Cross-Sectional Analysis.

Background: Bariatric surgery is an effective treatment for morbid obesity and its associated comorbidities. However, due to altered gastrointestinal anatomy and physiology, patients are at risk of developing nutritional deficiencies, which may impair long-term health and quality of life. Identifying the prevalence of such deficiencies is essential to guide appropriate follow-up and supplementation strategies. Objective: To determine the prevalence of nutritional deficiencies among patients who underwent bariatric surgery and to compare outcomes between sleeve gastrectomy and gastric bypass. Methodology: This cross-sectional analytical study included 365 patients who had undergone bariatric surgery. Adult patients aged 18-65 years with at least six months of postoperative follow-up were enrolled, while those with prior gastrointestinal surgery, chronic systemic illnesses or incomplete records were excluded. Data were collected on demographics, surgical procedure type and laboratory investigations including hemoglobin, ferritin, vitamin B12, folate, calcium and vitamin D. Standardized cut-off values were used to define deficiencies. Statistical analysis was performed using SPSS version 26, with results expressed as Mean±Standard deviation for continuous variables and frequencies and percentages for categorical variables. Comparisons between groups were made using Chi-square test, with p<0.05 considered significant. Results: Of 365 patients, 208 (57.0%) underwent sleeve gastrectomy and 157 (43.0%) gastric bypass. The mean age was 40.9±10.1 years and 220 (60.3%) were female. The most common deficiency was vitamin D, present in 202 patients (55.3%), followed by iron deficiency in 146 (40.0%) and anemia in 142 (38.9%). Vitamin B12 deficiency was observed in 110 (30.1%), folate in 81 (22.2%) and calcium in 76 (20.8%). Multiple deficiencies were noted in 134 patients (36.7%). Deficiencies were significantly more frequent in gastric bypass compared to sleeve gastrectomy for vitamin D (62.4% vs. 50.0%, p = 0.02) and iron (45.9% vs. 35.6%, p = 0.03). Women were more likely to have anemia (45.9% vs. 28.3%, p = 0.001) and vitamin D deficiency (60.5 vs. 47.6%, p = 0.01). The prevalence of deficiencies increased with time since surgery, with the highest rates observed beyond two years. Conclusion: Nutritional deficiencies are common after bariatric surgery, particularly vitamin D and iron deficiency and are more prevalent following gastric bypass than sleeve gastrectomy. Women and patients with longer follow-up durations are at greater risk. These findings underscore the need for structured postoperative monitoring, lifelong supplementation and patient education to prevent long-term health complications.