Effects of medical and surgical treatment on vitamin D levels in obesity.

INTRODUCTION: Persons living with obesity treated with bariatric surgery are at a high risk of developing nutritional deficiencies. The primary aim of this observational cohort study was to compare vitamin D levels in patients two years after bariatric surgery (Roux-en-Y gastric bypass/RYGB and sleeve gastrectomy/SG) with a very low-energy diet (VLED). The same subjects were also compared with a population sample from the same region at baseline. The primary hypothesis was that surgery, especially RYGB, would lead to an increased prevalence of vitamin D deficiency compared to subjects treated with VLED. 971 individuals eligible for surgical, RYGB (n = 388), SG (n = 201), and medical treatment (n = 382), in routine care, were included consecutively between 2015 and 2017. A random population sample from the WHO-MONICA project was used as a reference, (n = 414). S-calcium, S-25(OH)D (vitamin D), and S-PTH (parathyroid hormone) were measured in all persons with obesity at baseline and two years after treatment (n = 713). Self-reported use of vitamin D and calcium supplementation was registered. RESULTS: Vitamin D deficiency (S-25(OH)D <25mmol/l) was found in 5.2% of the persons with obesity at baseline versus 1.7% of the general population (SMD>0.1). S-25(OH)D increased for all treatment groups but was higher in RYGB and SG (SMD>0.1, standardized mean difference). Thirteen subjects (1.8%) had vitamin D deficiency after obesity treatment. CONCLUSION: Surgical intervention for obesity followed by vitamin D supplementation was not associated with a higher risk for vitamin D deficiency, irrespective of surgery type, compared to individuals on medical treatment. However, persons living with obesity seeking weight loss treatment are more likely to have deficient vitamin D levels compared to the general population.

Anaemia in patients with self-reported use of iron supplements in the BAriatric surgery SUbstitution and nutrition study: A prospective cohort study.

BACKGROUND AND AIMS: After bariatric surgery, micronutrient deficiencies may lead to anaemia. To prevent post-operative deficiencies, patients are recommended lifelong micronutrient supplementation. Studies investigating the effectiveness of supplementation to prevent anaemia after bariatric surgery are scarce. This study aimed to investigate the relationship between nutritional deficiencies and anaemia in patients who report use of supplementation two years after bariatric surgery versus patients who do not. METHODS AND RESULTS: Obese (BMI≥35 kg/m2) individuals (n = 971) were recruited at Sahlgrenska University Hospital in Gothenburg, Sweden between 2015 and 2017. The interventions were Roux-en-Y gastric bypass (RYGB), n = 382, sleeve gastrectomy (SG), n = 201, or medical treatment (MT), n = 388. Blood samples and self-reported data on supplements were collected at baseline and two years post treatment. Anaemia was defined as haemoglobin <120 g/L for females and <130 g/L for males. Standard statistical methods, including a logistic regression model and a machine learning algorithm, were used to analyse data. The frequency of anaemia increased from baseline in patients treated with RYGB (3·0% vs 10·5%; p < 0·05). Neither iron-dependent biochemistry nor frequency of anaemia differed between participants who reported use of iron supplements and those who did not at the two-year follow-up. Low preoperative level of haemoglobin and high postoperative percent excessive BMI loss increased the predicted probability of anaemia two years after surgery. CONCLUSION: The results from this study indicate that iron deficiency or anaemia may not be prevented by substitutional treatment per current guidelines after bariatric surgery and highlights there is reason to ensure adequate preoperative micronutrient levels. TRIAL REGISTRATION: March 03, 2015; NCT03152617.