Experience of vitamin D supplementation — is it possible to influence the metabolic and cardiovascular risk in obese children?

Abstract

Background. Obese adolescents are at a greater risk of vitamin D deficiency, which is related to bone and metabolic changes. Vitamin D deficiency is associated with a higher prevalence of metabolic syndrome, type 2 diabetes mellitus in children and adolescents. Objective. To evaluate efficacy and safety of 3‑and 6‑month therapy with 1500 IU and 2000 vitamin D months in obese children and adolescents, and to assess whether increased circulating 25‑hydroxyvitamin D (25 (OH)D) level is associated with improved markers ofinsulin sensitivity and resistance, serum leptin and adiponectin levels and reduction of body mass index (BMI). Design and methods. Altogether 66 obese children and adolescents (mean age — 12,6 ± 2,2 years; BMI — 32 ± 6,22 kg/m2 , 25 (OH)D: 16,7 ± 5,58 ng/ml) were recruited from the Pediatric Endocrinology Unit from Almazov North-West Medical Research Centre and were assigned to receive either vitamin D3 (1500 IU/day and then 2000 IU/day) as a part of their standard care. Anthropometric parameters, adipokines (leptin, adiponectin), fasting glucose, insulin, triglyceride levels and HOMA-IR (Homeostasis Model Assessment of Insulin Resistance) were measured at baseline and at 2 follow-up visits at 3 and 6 months. Results. Vitamin D deficiency has a high prevalence in both obese and non-obese children from St Petersburg. Vitamin D 1500 IU per day was prescribed to obese children for 3 months followed by 2000 IU per day during subsequent 3 months. At 3 and 6 months vitamin D supplementation was associated with an increase in the serum levels of 25 (OH)D, adiponectin and insulin sensitivity. However, BMI and serum leptin level remained unchanged in the majority of children. The unfavourable changes in some of the indices in 6 month might be due to the decreased adherence to treatment. Conclusions. Diet vitamin D supplement (1500 and 2000 IU/day) is effective to normalize plasma level of 25 (ОН)D in 40% of children. It leads to an increase in adiponectin level and a decrease in HOMA-IR and triglyceride level, but it does not affect BMI. Diet vitamin D supplement may be an effective additional approach to obesity management associated with the favourable metabolic and cardiovascular effects.