Occurrence of Vitamin D Deficiency among Women in North Sumatera, Indonesia

ABSTRACT

Low levels of serum 25(OH)D in women are reported in temperate countries, and increasingly so in tropical countries but few such studies have been reported in Indonesia. This study was aimed at assessing the serum vitamin D status and its associated factors in a sample of Indonesian women Methods: A cross-sectional study was conducted on 156 apparently healthy women during the dry season in North Sumatera. The measurements carried out included exposure to sun's rays, intake of vitamin D food sources, reported physical activity, body fatness (by bioelectrical impedance analysis), and serum 25(OH)D levels (by chemiluminescent immunoassay). Serum 25(OH)D levels were categorised into deficient(<20 ng/mL), insufficient (20-32 ng/mL), sufficient (32-100 ng/ mL), and normal for tropical countries (54-90 ng/mL). Statistical analysis included Pearson correlation, independent t-test, and one way ANOVA tests. Results: The mean age of the subjects was 35.6±7.7 years, with about 70% working indoors. About half of the women were obese. The majority had low vitamin D intake. More than half had sun ray exposure of less than 1 hour, and moreover, nearly two-thirds of them wore the 'hijab' that covers most parts of their body. The majority of women reported low physical activity level. The mean serum 25(OH)D level of the subjects was 17.71 ng/mL (95% CI 16.22, 19.34 ng/mL). Of the total, 95% (148) were in the vitamin D deficient-insufficient category, with the remaining 5% in the sufficient category. An association was found between occupation, dietary intake of vitamin D, sun ray exposure, and physical activity levels with serum vitamin D concentrations. Conclusion: The results showed that vitamin D deficiency can occur in women living in a tropical country if they have sun-avoiding lifestyles, work indoors, and have low dietary intake of vitamin D.