Vitamin D status in Sri Lankans living in Sri Lanka and Norway

Vitamin D deficiency is common in non-Western immigrant groups living in Western countries. A comparison of vitamin D status in individuals who have emigrated and individuals who remain in their country of origin is needed in order to provide information about the effect of moving to northern latitudes. A total of 196 participants aged 30-60 years in a cross-sectional population-based study in Kandy, Sri Lanka (latitude 7 degrees north) and 242 Sri Lankans aged 31-60 years participating in a cross-sectional population-based study in Oslo, Norway (latitude 60 degrees north) were included in the analysis. All serum samples were analysed for serum 25-hydroxyvitamin D (s-25(OH)D) in the same laboratory. Sri Lankans living in Norway had substantially lower s-25(OH)D (mean 31.5 nmol/l) compared with those living in Sri Lanka (mean 54.2 nmol/l), and the prevalence of s-25(OH)D < 25 nmol/l was 9.3 times higher (95 % CI 4.4, 19.6) in Norway compared with Sri Lanka. In Sri Lanka there was a clear seasonal variation with the lowest s-25(OH)D levels in August-September and the highest levels in November-December. We conclude that vitamin D status among Sri Lankans living in Kandy, Sri Lanka was considerably higher than that among Sri Lankans living in Oslo, Norway. The low vitamin D status commonly observed in non-Western immigrant groups living at northern latitudes should not be regarded as normal levels for these groups. However, also in Sri Lanka we found a profound seasonal variation with the lowest levels in August and September after the Monsoon.