25-hydroxyvitamin D is differentially associated with calcium intakes of Northern, Central, and Southern European adolescents: Results from the HELENA study.

Objectives: Adolescents in the European Union (EU) exhibit a higher prevalence of vitamin D (VitD) deficiency than other age groups. The degree to which sunlight exposure 25-hydroxyvitamin D [25(OH)D] concentrations depends on a variety of factors, including diet. Nevertheless, the relationship between calcium and VitD intake and 25(OH)D concentrations has not been previously studied among adolescents living in different EU countries and consequently in different latitudes. Therefore, the aim of this study was to examine whether calcium and VitD intakes are differentially associated with 25(OH)D in adolescents from northern, central and southern EU countries.

Methods: The present analysis included 178 adolescents from northern EU countries, 251 from central EU countries, and 212 from southern EU countries (ages 12.5-17.5 y). Mixed model linear regression analyses stratified by geographic location were used to verify associations between calcium and VitD intake and 25(OH)D concentrations. Age, Tanner stage, seasonality, energy intake, and supplement use were entered as covariates.

Results: Only the calcium intake of central EU adolescents was positively associated with 25(OH)D (α = 0.005; 95% confidence interval, 0.007-0.028).

Conclusions: Further longitudinal studies should confirm these observations, as this could be important for future public health interventions aiming to increase 25(OH)D concentrations in adolescents.