Is vitamin D deficiency in obese youth a risk factor for less weight loss during a weight loss program?

Response to vitamin D replacement therapy in obese children and adolescents with vitamin D deficiency: a randomized controlled trial

OBJECTIVES

Vitamin D deficiency is common in the pediatric group with obesity and is a risk factor for metabolic syndrome. Supplementation of vitamin D may require higher dosing than in normal-weight children. The aim of our study was to investigate the response of supplementation on vitamin D levels and the metabolic profile in youths with obesity.

METHODS

Children and adolescents with obesity (Body mass index >2.3 SDS, age ≤18 years) and hypovitaminosis D (level <20 μg/L) who entered a residential weight-loss program in Belgium, were included during summer. Subjects were randomized: Group 1 received 6,000 IU vitamin D daily for 12 weeks, whereas Group 2 simultaneously participating in the weight-loss program received no supplementation. Differences in vitamin D levels, weight, insulin resistance, lipid patterns, and blood pressure after 12 weeks were assessed.

RESULTS

A total of 42 subjects (12-18 years) with hypovitaminosis D were included, group 1 (n=22) received supplementation after randomization. After 12 weeks, a median increase in vitamin D levels of 28.2 (24.1-33.0) and 6.7 (4.1-8.4) µg/L was observed in group 1 and group 2, respectively (p-value<0.001), resulting in vitamin D sufficiency in 100 and 60% of subjects. No significant differences in weight loss (p-value 0.695), insulin resistance (p-value 0.078), lipid patterns (p-value 0.438), or blood pressure (p-value 0.511) were observed between both groups after 12 weeks of treatment.

CONCLUSIONS

Supplementation with 6,000 IU vitamin D daily during 12 weeks in children and adolescents with obesity and hypovitaminosis D is safe and sufficient to reach vitamin D sufficiency. However, no positive effects on weight loss, insulin resistance, lipid patterns, or blood pressure were observed.

The Predictive Value of Adipokines and Metabolic Risk Factors for Dropouts and Treatment Outcomes in Children With Obesity Treated in a Pediatric Rehabilitation Center

Background

Inpatient pediatric obesity treatments are highly effective, although dropouts and weight regain threaten long-term results. Preliminary data indicate that leptin, adiponectin, and cardiometabolic comorbidities might predict treatment outcomes. Previous studies have mainly focused on the individual role of adipokines and comorbidities, which is counterintuitive, as these risk factors tend to cluster. This study aimed to predict the dropouts and treatment outcomes by pre-treatment patient characteristics extended with cardiometabolic comorbidities (individually and in total), leptin, and adiponectin.

Methods

Children aged 8-18 years were assessed before, immediately after and 6 months after a 12-month inpatient obesity treatment. Anthropometric data were collected at each visit. Pre-treatment lipid profiles; glucose, insulin, leptin, and adiponectin levels; and blood pressure were measured. The treatment outcome was evaluated by the change in body mass index (BMI) standard deviation score (SDS) corrected for age and sex.

Results

We recruited 144 children with a mean age of 14.3 ± 2.2 years and a mean BMI of 36.7 ± 6.2 kg/m2 corresponding to 2.7 ± 0.4 BMI SDS. The 57 patients who dropped out during treatment and the 44 patients who dropped out during aftercare had a higher pre-treatment BMI compared to the patients who completed the treatment (mean BMI, 38.3 ± 6.8 kg/m2 vs 35.7 ± 5.5 kg/m2) and those who completed aftercare (mean BMI, 34.6 ± 5.3 kg/m2 vs 37.7 ± 6.3 kg/m2) (all p<0.05). Additionally, aftercare attenders were younger than non-attenders (mean age, 13.4 ± 2.3 years vs 14.9 ± 2.0, p<0.05).Patients lost on average 1.0 ± 0.4 SDS during treatment and regained 0.4 ± 0.3 SDS post-treatment corresponding to regain of 43 ± 27% (calculated as the increase in BMI SDS post-treatment over the BMI SDS lost during treatment). A higher BMI and more comorbidities inversely predicted BMI SDS reduction in linear regression (all p<0.05).The absolute BMI SDS increase after returning home was predicted by pre-treatment leptin and systolic blood pressure, whereas the post-treatment BMI SDS regain was predicted by pre-treatment age, leptin, and adiponectin levels (all p<0.05) in multivariate linear regressions.

Conclusion

Patients who need treatment the most are at increased risk for dropouts and weight regain, emphasizing the urgent need for interventions to reduce dropout and support inpatients after discharge. Furthermore, this study is the first to report that pre-treatment leptin and adiponectin levels predict post-treatment BMI SDS regain, requiring further research.

Vitamin D effects and endocrine diseases

A lack of vitamin D has been linked to autoimmune diseases including type 1 diabetes, autoimmune thyroiditis and to obesity. The prevalence of vitamin D deficiency is higher in diabetic or obese children and patients with thyroiditis compared to healthy controls. Moreover, low vitamin D values seem to be associated with major complications and poor glycemic control, in particular in obese children. Supplementation with vitamin D, which has immune-regulatory properties, may support our therapies and improve the outcomes in different diseases. Although some studies suggest a possible role of vitamin D in the etiology of autoimmune diseases and obesity, data on supplementation benefits are inconclusive and further studies are needed. In this paper, we focus on the current evidence regarding vitamin D function in endocrine diseases and possible benefits of its supplementation in pediatric age.