The Link Between Obesity And Vitamin D in Bariatric Patients With Omega-loop Bypass Surgery

Study Overview
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Brief Summary
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The aim of the study is to increase vitamin D concentrations or to keep it on high level, respectively, by supplementing with vitamin D3 in a different dose regime, and to improve the overall health status in bariatric patients. In this project, the vitamin D status, the parameters of inflammation, bone turnover, insulin resistance, liver and depression score of bariatric patients are expected to improve, due to supplementation of a loading dose compared to the standard therapy.

Official Title
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The Link Between Obesity And Vitamin D in Bariatric Patients With Omega-loop Bypass Surgery: a Randomized Controlled, Double-blinded Clinical Supplementation Trial

Conditions
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Bariatric Surgery Candidate

Intervention / Treatment
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* Drug: Cholecalciferol
* Drug: Placebo


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Planned omega loop bypass surgery 25-hydroxy vitamin D < 75 nmol/l BMI >40 or ≥35 kg/m2 with co-morbidities e.g. diabetes mellitus, hypertension Body weight <140 kg (due to limitation of DEXA measurement) Capability to consent Exclusion Criteria: Another planned form of bariatric surgery Hypercalcemia (calcium >2.63 mmol/l) or hypocalcemia (<1.75 mmol/l) Renal insufficiency (creatinine >133 μmol/l or GFR <50 ml/min) Primary hyperparathyroidism Malignancy Infection e.g. human immunodeficiency virus Medical conditions requiring daily calcium supplements or antacid use Known hypersensitivity to cholecalciferol No capability to consent Imprisoned persons

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 100 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Intervention<br>The loading dose of 300 000 IU is divided into three doses (100 000 IU) and will be given over the first months. All patients in the intervention group will receive the first loading dose of 100 000 IU at day of discharge. The second (2 weeks) and third (4 weeks postoperative) administration will be given based on the 25-hydroxy vitamin D concentration. After the last respectively third loading dose a maintenance dose of 3420 IU per day should maintain the high 25-hydroxy vitamin D concentration. It should be administered for up to 46 weeks (until follow-up visit) | Drug: Cholecalciferol<br> <br> |
| Placebo Comparator: Placebo<br>The placebo loading dose (oil) is divided into three administrations and will be given over the first months. All patients in the placebo group will receive the first placebo loading dose at day of discharge. After the last placebo loading dose a maintenance dose of 3420 IU per day should maintain the 25-hydroxy vitamin D concentration. It should be administered for up to 46 weeks (until follow-up). | Drug: Placebo<br> <br> |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| 25-hydroxy vitamin D levels | 25-hydroxy vitamin D levels after 24 weeks measured in intervention and placebo group, adjusting for the baseline value as covariate | 24 weeks postoperatively | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Prevalence of sufficient vitamin D | Number of patients reaching 25-hydroxyvitamin D levels above 75 nmol/l | 24 weeks postoperatively | 
| Prevalence of vitamin D deficiency | Prevalence of vitamin D deficiency | 24 weeks postoperatively | 
| Co-morbidities | Prevalence of Co-morbidities | 24 weeks postoperatively | 
| Prescribed medication | Change in prescribed medication | 24 weeks postoperatively | 
| Body weight, body composition | Change in body weight and body composition by bioelectrical impedance analysis | 24 weeks postoperatively | 
| Blood pressure | Change of vital signs (blood pressure) | 24 weeks postoperatively | 
| Laboratory parameters | Change in laboratory parameters compared to baseline: vitamin D status, bone turnover markers, calcium homeostasis, parathyroid hormone, inflammation, insulin resistance | 24 weeks postoperatively | 
| Depression symptoms | Prevalence of depression symptoms assessed by Beck Depression Inventory Questionnaire | 24 weeks postoperatively | 
| Bone mineral density and body fat content | Assessment of bone mineral density and total body fat content by DEXA | 24 weeks postoperatively | 
| Liver condition | Measurement of liver stiffness and fat content by FibroScan and CAP | 24 weeks postoperatively | 
| Dietary assessment | Dietary assessment will be documented with a 5-day food record to calculate vitamin D intake and the Mediterranean Score (questionnaire with calculated score) | 24 weeks postoperatively | 
| Gut microbiota composition | Association between vitamin D, gut microbiota and surgery-induced weight loss, by collecting stool samples | 24 weeks postoperatively | 
| Vitamin D in adipose and liver tissue | For instance, for the purposes of describing adipose depot vitamin D concentrations and expression of enzymes in subcutaneous, visceral adipose and liver tissue samples will be collected during the omega loop gastric bypass surgery. Furthermore, the liver tissue samples should be used in addition for a histological examination as extended diagnostics (NAFLD/ NASH). | during surgery | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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vitamin D, supplementation, Bariatric surgery