Sources of vitamin D and determinants of serum 25-hydroxyvitamin D in Finnish adolescents

Purpose To study the intake and sources of vitamin D and determinants of serum 25-hydroxyvitamin D (S-25(OH)D) in Finnish adolescents. Methods We studied 265 adolescents (117 girls) aged 15–17 years attending 8-year examinations of the PANIC Study, assessed diet using food records and other lifestyle factors by questionnaires, and analyzed S-25(OH)D by chemiluminescence immunoassay and determinants of S-25(OH)D using multivariate linear regression. Results Mean (standard deviation) of total vitamin D intake from food and supplements was 19.2 (13.1) µg/d, and that of dietary vitamin D intake was 9.9 (5.4) µg/d. Milk fortified with vitamin D was the main dietary source of vitamin D, providing 45% of daily intake. Altogether, 29% of the adolescents used no vitamin D supplements and 25% did not meet the recommended total vitamin D intake of 10 µg/d. Mean (standard deviation) of S-25(OH)D was 62.0 (18.8) nmol/l, and S-25(OH)D was