Serum Vitamin D Depends Less on Latitude Than on Skin Color and Dietary Intake During Early Winter in Northern Europe.

Abstract

To evaluate if dietary vitamin D intake is adequate for sufficient vitamin D status during early winter in children living in Sweden, irrespective of latitude or skin color. As part of a prospective, comparative, 2-center intervention study in northern (63°N) and southern (55°N) Sweden, dietary intake, serum 25-hydroxyvitamin D (S-25(OH) D), associated laboratory variables, and sociodemographic data were studied in 5 to 7-year-old children with fair and dark skin in November and December. Two hundred six children with fair/dark skin were included, 44/41 and 64/57 children in northern and southern Sweden, respectively. Dietary vitamin D intake was higher in northern than southern Sweden (P = 0.001), irrespective of skin color, partly due to higher consumption of fortified foods, but only met 50-70% of national recommendations (10 μg/day). S-25(OH) D was higher in northern than southern Sweden, in children with fair (67 vs 59 nmol/L; P < 0.05) and dark skin (56 vs 42 nmol/L; P < 0.001). S-25(OH) D was lower in dark- than fair-skinned children at both sites (P < 0.01), and below 50 nmol/L in 40 and 75% of dark-skinned children in northern and southern Sweden, respectively. Insufficient vitamin D status was common during early winter in children living in Sweden, particularly in those with dark skin. Although, higher dietary vitamin D intake in northern than southern Sweden attenuated the effects of latitude, a northern country of living combined with darker skin and vitamin D intake below recommendations are important risk factors for vitamin D insufficiency.