Vitamin D status and associated metabolic factors in North Korea refugees in South Korea = Vitamin D status and associated metabolic factors in North Korea refugees in South Korea

다국어 초록 (Multilingual Abstract)

Background/Aims: Vitamin D deficiency defined as serum 25(OH)D level less than 20 ng/ml has been a major health problem in modern society regardless of age, sex, ethnicity, and region especially for immigrant populations. The purpose of this study is to investigate the vitamin D status and the prevalence of vitamin D insufficiency in North Korea Refugees living in South Korea, and also identify the associated factors of vitamin D insufficiency, and the relationship between metabolic syndrome and vitamin D insufficiency in this group. Methods: This study is based on the data from NORNS (North Korea refugee health iN South Korea). A total of 647 NKRs voluntarily took part in the survey and data was collected from October 2008 to November 2011 once a month at the Korea University Anam Hospital in Seoul. They were initially interviewed about general demographic information and a medical check-up consisting of anthropometric and various biochemical measurement was conducted. Among the 647 subjects, only 386 subjects were measured serum 25(OH)D level. Results: Among a total of 386 subjects, vitamin D insufficiency was found in 76.8% of male and 89.8% in females, whereas there is no one who have serum 25(OH)D level higher than 30 ng/ml in both sexes. The associated risk factors of vitamin D insufficiency were female, winter, smoking history and high systolic blood pressure. We found out the relationship between BMI and serum 25(OH)D level, underweight subjects with BMI below 20 kg/m2 had significantly lower serum 25(OH)D level compared with normal BMI (20 to 23 kg/m2) subjects. Controlling for age, sex, season, length of residence in South Korea, physical activities, the odd ratio of metabolic syndrome in subjects of serum 25(OH)D level below 10 ng/mL was 7.6 times higher compared with those of above 20 ng/ml (OR=7.6; 95% CI=1.63-35.8). Conclusions: The prevalence of vitamin D insufficiency is significantly high in North Korea refugees. The associated factors of vitamin D insufficiency are female, winter, smoking history. Vitamin D insufficiency is not related with obesity like previous studies but seem to be related with metabolic syndrome.