Vitamin D Levels in Residents of Arkhangelsk During Different Seasons of the Year

Abstract

Living in high latitudes is a risk factor for developing vitamin D deficiency. Literature data indicate that in the northern regions vitamin D cannot be synthesized in the skin for most of the year. It seems relevant to study vitamin D levels in the population of the Arctic zone of the Russian Federation during different seasons of the year, which was the purpose of our research. Materials and methods. We assessed 25(OH)D levels in 913 residents of the city of Arkhangelsk (64°N) in the course of three seasons: winter, spring, and autumn. The study included 191 children aged 7–8 years, of which 107 boys and 84 girls; 403 adolescents aged 13–17 years, of which 167 boys and 236 girls; 260 young people aged 18–22 years, of which 58 men and 202 women; 59 adults aged 24–65 years, of which 12 men and 47 women. Results. We revealed low vitamin D levels in residents of arkhangelsk qualifying as deficient throughout all three seasons. The median concentration of 25(OH)D was 16.3 (12.0–21.8) ng/ml in winter,16.9 (12.8–22.9) ng/ml in spring, and 15.8 (11.4–20.2) ng/ml in autumn. The proportion of subjects with a normal level of 25(OH)D wаs less than 1 % in winter, 8 % in spring, and 2 % in autumn. We revealed no dependence of 25(OH)D concentration on the average daylight duration or significant differences in 25(OH)D levels in different seasons of the year. Presumably, these results can be explained by the low amount of daylight hours spent outdoors by the subjects during the three seasons of the year. Further research is required on the contribution of various factors affecting 25(OH)D levels: length of time spent outdoors, level of physical activity, contribution of dietary sources of vitamin D.