Vitamin D deficiency in reproductive age Mongolian women: a cross sectional study

Abstract

Vitamin D production is critical not only for rickets prevention but for its role in several chronic diseases of adulthood. Maternal vitamin D status also has consequences for the developing fetus. This study assessed the prevalence of vitamin D deficiency (serum 25-hydroxyvitamin D [25(OH)D]<20ng/ml) and insufficiency [25(OH)D=20-29ng/ml] in spring, among reproductive age Mongolian women. Blood was drawn in March and April, 2009 from 420 Mongolian women, 18-44 years of age. Serum 25(OH)D concentrations were measured, anthropometric measurements were performed and information was collected by interview on lifestyle, dietary and reproductive factors. Logarithm-transformed 25(OH)D levels were compared across risk factor categories by analysis of variance. Linear regression analysis was used to assess the independent associations of factors with vitamin D status. Cutaneous vitamin D3 synthesis was assessed between December and July using a standard 7-dehydrocholesterol ampoule model. The vast majority of women 415 (98.8%) had serum 25(OH)D<20ng/ml (50nmol/l) with an additional 4 women (<1%) in the insufficient range (20-29ng/ml); only one women (0.2%) had sufficient levels (>30ng/ml or 75nmol/l). 25(OH)D concentrations were positively and independently associated with educational status and use of vitamin D supplements, but not with other demographic, lifestyle, reproductive, or anthropometric factors. 25(OH)D levels were not associated with dietary factors in this population, as there is little access to foods containing vitamin D in Mongolia. No production of previtamin D3 was observed until March and was maximally effective in April and was sustained through July. These data suggest that the prevalence of vitamin D deficiency in spring among reproductive age women in Mongolia is high. Given the lack of naturally vitamin D-rich food in the diet and limited use of vitamin D supplements, food fortification and/or supplementation with vitamin D should be considered among these women.

Keywords: 25(OH)D; 25-Hydroxyvitamin D; 25-hydroxyvitamin D; BMI; Healthy women; RDA; Reproductive age; Vitamin D; Vitamin D deficiency; body mass index; recommended dietary allowance.

Figure 1

Plot of serum 25-hydroxyvitamin D [25(OH)D] values by age, March–April 2009

Figure 2

Percent conversion of 7-dehydroxycholesterol (7-DHC) to previtamin D₃ (preD₃) in ampoules containing 7-DHC. They were placed outside in direct sunlight in Ulaanbaatar in at various months for one hour (from 12:30 p.m. to 1:30 p.m) at noon. The samples were stored in the dark and evaluated by high-performance liquid chromatography (HPLC). *The data for May is not stated because the ampoule was damaged