Publication Details
Abstract
Background: Vitamin D makes an important contribution to a variety of processes in human health, including immune system and bone metabolism and other metabolic processes. There are many reports that have shown an inverse association between body mass index (BMI) and blood vitamin D concentrations suggesting an association between vitamin D deprivation and the states of obesity. The incidence of vitamin D deficiency is very common in Iraq, in spite of the amount of solar exposure the population is receiving, especially in females. The association of body mass index (BMI) with vitamin D in Iraqi women remain poorly understood and needs to be further investigated. The aim of this study was to provide an insight into the association of BMI and the blood level of vitamin D in Iraqi women, as well as, the effect of sun exposure, physical activity, and consumption of vitamin D on the status of this vitamin. Patients and Methods: This cross sectional study included 98 Iraqi women and classified them into three groups according to BMI; normal weight:(BMI < 25kg/m²), overweight:(BMI ≤ 30kg/m²) and obese:(BMI ≥ 30kg/m²). Serum 25(OH)D concentrations were measured using chemiluminescence immunoassay (CLIA). Lifestyle factors were assessed, including sunlight exposure, physical activity (steps taken daily), and food vitamin D. Pearson's correlation coefficient was used to assess the relationship between BMI and vitamin D levels, and a one-way ANOVA was performed to evaluate the difference in vitamin D levels between groups of subjects with different BMIs. Because vitamin D is a fat-soluble vitamin, multiple linear regression analysis was carried out in order to determine independent variables associated with vitamin D status. Results: The relationship between serum 25(OH)D and BMI was inverse (r = −0.41, p = 0.032). Women that did not get adequate sunshine each day had significantly lower vitamin D levels (p = 0.014). Increased physical activity (6,000 steps/day) was inversely associated with serum vitamin D levels (p = 0.027). • Based on results from multiple linear regression, BMI had a significant adverse effect on human vitamin D status (β = −0.34; p = 0.039). Conclusion: Over-weight or obese Iraqi women had lower vitamin D levels than those with normal weight. In contrast, the results demonstrate that consumption of dairy products, higher sunshine and increased physical activities, in relation to vitamin D levels, has improved.