Kelishadi Roya, Moeini Roksana, Poursafa Parinaz, Farajian Sanam, Yousefy Hosseinali, Okhovat-Souraki Ali-Asghar
Paediatr Int Child Health. 2014 Feb;34(1):50-5. doi: 10.1179/2046905513Y.0000000080. Epub 2013 Dec 6.
To determine the association between air pollution and vitamin D status in young children living in a sunny region.
This cross-sectional study of 100 children aged 4-10 years in Isfahan was conducted during 2011-2012. This industrial city has an arid climate and is the second most air-polluted city in Iran. Children were selected by random cluster sampling from various areas with different levels of air pollution. The air quality index (AQI) was recorded and demographic variables, dietary habits and levels of physical activity were determined by validated questionnaires. Serum concentrations of 25-hydroxyvitamin D [25(OH)D], calcium, phosphate, alkaline phosphatase and parathyroid hormone were measured. The P for trend for median (interquartile range) of variables was assessed across the AQI quartiles. The associations between AQI and biochemical values were assessed by multiple linear regression after adjustment for age, gender, BMI, diet and pattern of physical activity.
Ninety-seven children (46.4% boys) completed the study. The median (interquartile range, IQR) of serum 25(OH) D was 37.4 (22.5, 81.6) nmol/L. Median dietary vitamin D intake was 11.7 μg/day, i.e. 78% of the required daily amount. Vitamin D deficiency and insufficiency were detected in 37.9% and 46.3% of children, respectively. Median (IQR) exposure to ultraviolet B radiation in the AQI Quartile 4 area was significantly lower than in the Quartile 1 area [0.36 (0.35-0.38) watts per square metre (W/m(2)) vs 0.41 (0.39-0.44) W/m(2), respectively, P = 0.04]. Likewise, the corresponding figure for serum 25(OH)D was 35.2 (22.5-45.2) vs 52.7 (44.9-81.6) nmol/L, respectively, P = 0.04. AQI was inversely associated with serum 25(OH)D, which remained significant after adjustment for the above-mentioned confounding factors (β = 0.61, P = 0.01).
The independent inverse association of AQI with 25(OH)D explains the high prevalence of vitamin D deficiency in children in Isfahan. Dietary intake of vitamin D was not sufficiently low to explain the very low level of serum 25(OH)D. In regions with plenty of sunlight, air pollution should be considered to be a factor in the causation of hypovitaminosis D.
确定生活在阳光充足地区的幼儿空气污染与维生素D状况之间的关联。
2011 - 2012年期间，对伊斯法罕的100名4至10岁儿童进行了这项横断面研究。这座工业城市气候干旱，是伊朗空气污染第二严重的城市。通过随机整群抽样从空气污染水平不同的各个区域选取儿童。记录空气质量指数（AQI），并通过经过验证的问卷确定人口统计学变量、饮食习惯和身体活动水平。测量血清25 - 羟基维生素D [25(OH)D]、钙、磷、碱性磷酸酶和甲状旁腺激素的浓度。在AQI四分位数范围内评估变量中位数（四分位间距）的趋势P值。在对年龄、性别、BMI、饮食和身体活动模式进行调整后，通过多元线性回归评估AQI与生化值之间的关联。
97名儿童（46.4%为男孩）完成了研究。血清25(OH)D的中位数（四分位间距，IQR）为37.4（22.5，81.6）nmol/L。膳食维生素D摄入量中位数为11.7μg/天，即所需每日量的78%。分别在37.9%和46.3%的儿童中检测到维生素D缺乏和不足。AQI第4四分位数区域的紫外线B辐射暴露中位数（IQR）显著低于第1四分位数区域[分别为0.36（0.35 - 0.38）瓦每平方米（W/m²）对0.41（0.39 - 0.44）W/m²，P = 0.04]。同样，血清25(OH)D的相应数值分别为35.2（22.5 - 45.2）对52.7（44.9 - 81.6）nmol/L，P = 0.04。AQI与血清25(OH)D呈负相关，在对上述混杂因素进行调整后仍具有显著性（β = 0.61，P = 0.01）。
AQI与25(OH)D的独立负相关解释了伊斯法罕儿童维生素D缺乏的高患病率。膳食维生素D摄入量不足以低到解释血清25(OH)D的极低水平。在阳光充足的地区，空气污染应被视为维生素D缺乏症病因的一个因素。
