Prevalence and determinants of vitamin D deficiency and insufficiency among three immigrant groups in Finland: evidence from a population-based study using standardised 25-hydroxyvitamin D data.

OBJECTIVE: We investigated the determinants of serum 25-hydroxyvitamin D [S-25(OH)D] and dietary vitamin D sources among three immigrant groups in Finland and compared their S-25(OH)D to the general Finnish population. DESIGN: Cross-sectional population-based Migrant Health and Wellbeing Study and the nationally representative Finnish Health 2011 Survey. S-25(OH)D was standardised according to the Vitamin D Standardisation Program. Vitamin D sources were assessed by interview. SETTING: Six different municipalities in Finland (60 degrees -63 degrees N). PARTICIPANTS: Immigrants aged 18-64 years (446 Russians, 346 Somalis, 500 Kurds), 798 Finns aged 30-64 years. RESULTS: The mean of S-25(OH)D was 64 (95 % CI 62, 66), 44 (95 % CI 41, 46), 35 (95 % CI 34, 37) and 64 (95 % CI 62, 66) nmol/l for Russians, Somalis, Kurds and Finns, respectively. S-25(OH)D among Somalis and Kurds was lower compared with Finns (P < 0.001). The prevalence of vitamin D deficiency (S-25(OH)D <30 nmol/l) and insufficiency (S-25(OH)D <50 nmol/l) was higher among immigrants than Finns (P < 0.001). Vitamin D-rich foods differed between the groups; vitamin D-fortified fat spread consumption was higher among Somalis (91 %) than among Russians (73 %) and Kurds (60 %); fish was less consumed among Kurds (17 %) than among Russians (43 %) and Somalis (38 %); and 57 % Russians, 56 % Kurds and 36 % Somalis consumed vitamin D-fortified dairy daily (P < 0.001 for all). Daily smoking, alcohol consumption and winter blood sampling were determinants of vitamin D insufficiency (P