We Need to Put Vitamin D Back in Children and Adolescents

Small-scale studies have documented low vitamin D levels in children and adolescents, even as evidence mounts about the role of this vitamin in maintaining health and preventing disease. Three studies further our understanding of vitamin D status in children.

One study was based on data from 6275 children and adolescents who participated in the 2001–2004 National Health and Nutrition Examination Survey (NHANES). Overall, 9% of respondents (representing 7.6 million children and adolescents) were vitamin D deficient (serum 25 hydroxyvitamin D [25(OH)D] <15 ng/mL), and 61% (representing 50.8 million) were vitamin D insufficient (serum 25[OH]D, 15–29 ng/mL). Only 4% of participants reported taking 400 IU of vitamin D daily during the past 30 days. Among those aged 13–21 years, vitamin D deficiency was detected in 3% and 5% of white boys and girls, 43% and 59% of non-Hispanic black boys and girls, and 7% and 20% of Mexican American boys and girls. Deficiency rates were generally lower in children aged 7–12 years and lowest in children aged 1–6 years. Risk factors associated with deficiency were obesity (odds ratio, 1.9), drinking milk less than once per week (OR, 2.9), and television /video/computer use for more than 4 hours per day (OR, 1.6). Reported use of daily vitamin D supplements reduced the risk for deficiency (OR, 0.4). Compared with participants with vitamin D levels ≥30 ng/mL, those with deficiency had higher parathyroid hormone (PTH) levels and systolic blood pressure (BP) and lower HDL and serum calcium levels.

Other investigators used the same dataset to examine the effects of low serum 25(OH)D levels in 3577 fasting adolescents (age range, 12–19 years). In analyses that were adjusted for sociodemographic factors and physical activity, 25(OH)D levels were inversely associated with systolic BP and plasma glucose concentrations. Compared with children with vitamin D levels in the highest quartile (>26 ng/mL), those with levels in the lowest quartile (<15 ng/mL) had adjusted ORs of 2.36 for hypertension, 2.54 for fasting hyperglycemia (glucose ≥100 mg/dL), and 3.88 for metabolic syndrome.

In the third study, investigators examined the relation between serum 25(OH)D levels and insulin and glucose dynamics in 51 black adolescents (mean body-mass index, 43.3 kg/m²) at a hospital-based weight-management clinic. After controlling for BMI and PTH levels, the investigators found no metabolic differences between children with 25(OH)D levels <20 ng/mL and those with levels >20 ng/mL. However, insulin sensitivity was significantly lower and insulin resistance was higher among those with 25(OH)D levels <15 ng/mL compared with those with levels ≥15 ng/mL.