Sunlight Exposed Body Surface Area is Associated With Serum 25-hydroxyvitamin D (25(OH)D) Level in Pregnant Minangkabau Women, Indonesia

Abstract

Background: Vitamin D deficiency is highly prevalent in women, while living in a tropical country with year-round abundance of sunlight as the main source of vitamin D does not seem to guarantee adequate serum 25(OH)D. While living in the tropics, Minangkabau women are known to dress specifically according to their culture. This study was aimed to elucidate the association of sunlight exposed body surface area with serum 25(OH)D in pregnant Minangkabau women of Indonesia. Methods: A cross-sectional study was carried out on 88 Minangkabau women in late pregnancy. Data were collected by using questionnaire and 24-hour food recall, skin pigmentation was determined by Fitzpatrick scale, body surface area exposed to sunlight was assessed and serum 25(OH)D was quantified by ELISA method. Results: Nearly half of the subjects (n=40; 45.5%) were deficient in vitamin D (<20 ng/ml) with serum 25(OH)D level23.0±10.0 ng/ml (mean±SD) and estimated daily intake of vitamin D 5.6±3.9 µg/1000 kcal/day (mean±SD). Median percentage of body area exposed to sunlight was 15.8%. There were no differences in serum 25(OH)D levels according to sunlight exposure time, skin pigmentation type, and sunscreen use. Percentage of body area exposed to sunlight was positively correlated with serum 25(OH)D level (Spearman’s ρ =0.403; p<0.001). Conclusions: Vitamin D deficiency is prevalent in pregnant Minangkabau women and they need to consider increasing their body area exposure to sunlight. Keywords: body surface area, pregnant, sunlight exposure, vitamin D