title: Long-term effects of vitamin D supplementation in vitamin D deficient obese children participating in an integrated weight-loss programme (a double-blind placebo-controlled study) - rationale for the study design.
abstract: Obesity is associated not only with an array of metabolic disorders (e.g. insulin resistance, hiperinsulinemia, impaired tolerance of glucose, lipid disorders) but also skeletal and joint abnormalities. Recently, a pleiotropic role of vitamin D has been emphasized. Obese children frequently present with vitamin D deficiency, and greater fat mass is associated with lower serum concentration of this vitamin. Although some evidence suggests that weight loss may affect vitamin D status, this issue has not been studied extensively thus far. The aim of a double-blind placebo-controlled study is to assess long-term health effects of vitamin D supplementation in vitamin D deficient obese children participating in an integrated weight-loss programme.
  
  
  
  A randomized double-blind, placebo-controlled trial analysing the effects of vitamin D3 supplementation in overweight or obese vitamin D deficient (<30 ng/ml) children participating in an integrated weight-loss programme. Children are randomized to receive either vitamin D (1200 IU) or placebo for 26 weeks. Primary endpoints include changes in BMI (body mass index), body composition and bone mineral density at the end of the study period, and secondary endpoints - the changes in laboratory parameter reflecting liver and kidney function (transaminases, creatinine) and glucose homeostasis (glucose and insulin levels during oral glucose tolerance test).
  
  
  
  The effects of vitamin D supplementation in obese individuals, especially children, subjected to a weight-loss program are still poorly understood. Considering physiological processes associated with puberty and adolescent growth, we speculate that supplementation may enhance weight reduction and prevent bone loss in obese children deficient in this vitamin.
  
  
  
  NCT 02828228 ; Trial registration date: 8 Jun 2016; Registered in: ClinicalTrials.gov. The trial was registered retrospectively.
authors.affiliation: Department of Paediatrics, Gastroenterology, Hepatology and Nutrition, Medical University of Gdańsk, ul. Nowe Ogrody, 1-6 80-803, Gdańsk, Poland.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Szlagatys-Sidorkiewicz
authors.affiliation: Department of Public Health and Social Medicine, Medical University of Gdansk, Zwycięstwa 42a, 80-210, Gdansk, Poland. brzezinski@gumed.edu.pl.
authors.forename: Michał
authors.identifier: 0000-0002-3426-507X
authors.initials: M
authors.lastname: Brzeziński
authors.affiliation: Department of Paediatrics, Gastroenterology, Hepatology and Nutrition, Medical University of Gdańsk, ul. Nowe Ogrody, 1-6 80-803, Gdańsk, Poland.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Jankowska
authors.affiliation: "6-10-14 for Health" University Clinical Centre, Dębinki 7, 80-210, Gdansk, Poland.
authors.forename: Paulina
authors.initials: P
authors.lastname: Metelska
authors.affiliation: Pomeranian Medical Centre, Nowe Ogrody 1-6, 80-803, Gdansk, Poland.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Słomińska-Frączek
authors.affiliation: Department of Gastroenterology, Hepatology and Feeding Disorders, The Children's Memorial Health Institute, Dzieci Polskich 20, 00-999, Warsaw, Poland.
authors.forename: Piotr
authors.initials: P
authors.lastname: Socha
mesh_terms: D000293:Adolescent; D002648:Child; D002762:Cholecalciferol / Q000627:therapeutic use*; D002985:Clinical Protocols; D019587:Dietary Supplements; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D063766:Pediatric Obesity / Q000150:complications / Q000628:therapy*; D016896:Treatment Outcome; D014808:Vitamin D Deficiency / Q000150:complications / Q000188:drug therapy*; D014815:Vitamins / Q000627:therapeutic use*; D061217:Weight Reduction Programs
chemical_list: D014815:Vitamins; D002762:Cholecalciferol
keywords: Body composition; Obesity; Vitamin D; Weight loss