Spatial Epidemiology of Vitamin D Status in Mongolia

Abstract

TPS 723: Low and middle income countries: sanitation infections and other health effects, Exhibition Hall, Ground floor, August 26, 2019, 3:00 PM - 4:30 PM Background: Most Mongolians are known to have low vitamin D levels because of low availability and lack of dietary habit of vitamin D-rich foods, including fish and mushrooms. Moreover, solar radiation is inadequate to induce cutaneous synthesis of pre-vitamin D in winters because of Mongolia’s high latitude and highland location. This study aims to determine the spatial status of vitamin D in Mongolians. Methods: Serum 25-hydroxyvitamin D [25(OH)D], the most abundant vitamin D metabolite in circulation, was measured in 541 healthy subjects (age: 10–64 years) living in six Mongolian provinces and capital, Ulaanbaatar. Furthermore, blood samples were collected between September and December 2016. Results: The mean (± standard deviation) serum 25(OH)D concentration was 16.6 (± 7.0) ng/mL (recommended value, ≥30.0 ng/mL); furthermore, 70.1% of subjects had “deficient” (<20 ng/mL) and 24.2% had “insufficient” (20≤, <30 ng/mL) levels. The 25(OH)D levels were significantly lower in females (14.9 ± 5.9 ng/mL) than in males (19.5 ± 7.8 ng/mL), although no differentiation was noted by age. Subjects from Ulaanbaatar exhibited the lowest levels of 25(OH)D (7.9 ± 2.6 ng/mL) compared with all provinces, with significant differences even if seasonal sampling blood was considered. Furthermore, the 25(OH)D levels were relatively high in provinces in southern Mongolia. Conclusions: Mongolians have deficient vitamin D levels, especially in Ulaanbaatar, which could be partly attributed to the impact of air pollution; Ulaanbaatar is the most air polluted area in Mongolia (annual mean: PM2.5, 6–10 times higher than the safety level), which decreases the amount of ultraviolet-B radiation required for the synthesis of pre-vitamin D. Therefore, a comprehensive policy, including dietary modification and the remedy for air pollution, is warranted.