Vitamin D supplementation in adolescents with obesity and vitamin D deficiency does not improve endothelial function despite the normalization of vitamin D levels, according to research in Pediatric Obesity.
In an open-label, prospective study examining the effect of monthly vitamin D supplementation on endothelial function in adolescents with obesity, researchers also found that participants increased their total cholesterol after 3 months of supplementation.
“We’re not saying it’s bad to take vitamin D supplements at reasonable doses, and we know most obese teens are vitamin D deficient,” Seema Kumar, MD, a pediatric endocrinologist with Mayo Clinic in Rochester, Minnesota, said in a press release. “We’re just saying the jury is still out on how useful it is for improving overall health in adolescents.”
Kumar and Asma Javed, MBBS, a pediatric endocrinologist with Mayo Clinic, and colleagues analyzed data from 19 children with obesity aged 13 to 18 years (mean age, 16 years; mean BMI, 36.1 kg/m²; 89.5% white) with 25-hydroxyvitamin D levels less than 75 nmol/L. Researchers assigned the children 100,000 IU of oral vitamin D once monthly for 3 months. Researchers assessed endothelial function with flow-mediated dilation of the brachial artery at baseline and 1 month after the third dose of vitamin D, and measured calcium, glucose, fasting lipids, insulin and high-sensitivity C-reactive protein.
Researchers found that mean vitamin D levels increased from 55.9 nmol/L to 86.9 nmol/L (P < .01), but found no correlation between vitamin D levels and flow-mediated dilation of the brachial artery and no significant change in brachial artery flow-mediated dilation after vitamin D treatment. Serum parathyroid hormone declined from 3.8 pmol/L to 3.1 pmol/L; all other measurements showed no significant change after treatment.
The researchers noted that it remains unclear whether other treatment protocols, including daily or weekly vitamin D doses, could have a different effect on endothelial function.
“Using high dose of vitamin D for the purpose of decreasing cardiovascular disease in obese adolescents cannot be justified at this time,” Kumar told Endocrine Today. “Controlled vitamin D trials over a longer period of time, in which children with endothelial dysfunction are randomly allocated to vitamin D supplement or placebo, are needed to clarify the effect of vitamin D on CV health.” – by Regina Schaffer
Disclosure: The researchers report no relevant financial disclosures.