Vitamin D status in healthy Italian school-age children: a single-center cross-sectional study

Vitamin D is involved in calcium homeostasis and bone metabolism, although its extra-skeletal actions are also well-known. Low serum 25(OH)D levels are common both in adults and children worldwide.

The purpose of this cross-sectional study was to determine the distribution of 25(OH)D levels in a cohort of healthy Italian school-age children, aged 5-10 years, in relationship to determinants of vitamin D deficiency such as season, BMI, gender, age and ethnicity.

The mean serum 25(OH) D level was 28.2 ng/mL; the prevalence of 25(OH)D sufficiency (> 30 ng/mL), insufficiency (20-30 ng/mL), deficiency (10-20 ng/mL) and severe deficiency (< 10 ng/mL) was 36%, 37%, 21% and 6% of the study-group population, respectively. The lower serum 25(OH)D values were observed during winter (21.6 ng/mL) and spring (22.9 ng/mL), as compared to summer (46.7 ng/mL) (p < 0.001). Higher BMI z-scores were associated with lower 25(OH)D level while no statistical difference was observed as related to gender and age groups.

Healthy Italian schoolchildren show low 25(OH)D levels, particularly during winter and spring time. Seasonality, ethnicity and overweight/obesity were confirmed to influence the vitamin D status, thus indicating the need for effective initiatives to support adequate vitamin D status in this population group.