Bose Sonali, Breysse Patrick N, McCormack Meredith C, Hansel Nadia N, Rusher Robert R, Matsui Elizabeth, Peng Roger, Curtin-Brosnan Jean, Diette Gregory B
Nutr J. 2013 Jun 12;12:81. doi: 10.1186/1475-2891-12-81.
The inner-city pediatric population in the United States has a disproportionate burden of asthma. Recent attention has focused on the immunomodulatory role of vitamin D, which may be protective against disease morbidity. As the primary determinant of vitamin D status in humans is exposure to sunlight, we aimed to determine if 25-OH vitamin D levels in urban preschool children with asthma were low, influenced by time spent outdoors, and associated with asthma morbidity.
Serum 25-OH vitamin D levels were measured at baseline in a cohort of 121 inner-city children ages 2-6 years with asthma in Baltimore, MD. Participants were followed longitudinally at 3 and 6 months to assess time spent outdoors, asthma symptoms through questionnaires and daily diaries, and allergic markers.
In a predominantly black population of preschool children, the median 25-OH vitamin D level was 28 ng/mL (IQR 21.2-36.9), with 54% of the children below the traditionally sufficient level of 30 ng/mL and 7.4% in the range associated with risk of rickets (< 15 ng/mL). The median time spent outdoors was 3 hours/day (IQR 2-4), and greater time spent outdoors was not associated with higher vitamin D levels. 25-OH vitamin D did not show seasonal variation in our cohort (p = 0.66). Lower 25-OH levels were correlated with higher IgE levels.
Urban African-American preschool children with asthma have high rates of vitamin D insufficiency, and increased outdoor exposure is unlikely to correct these low 25-OH vitamin D levels. Repletion in this population may require dietary supplementation.
美国市中心的儿科人群哮喘负担过重。最近的研究重点集中在维生素D的免疫调节作用上，它可能对疾病发病具有保护作用。由于人类维生素D水平的主要决定因素是阳光照射，我们旨在确定城市学龄前哮喘儿童的25-羟维生素D水平是否较低，是否受户外活动时间影响，以及是否与哮喘发病率相关。
在马里兰州巴尔的摩市，对121名年龄在2至6岁的市中心哮喘儿童进行了队列研究，在基线时测量血清25-羟维生素D水平。对参与者进行为期3个月和6个月的纵向随访，以评估户外活动时间、通过问卷和每日日记记录的哮喘症状以及过敏指标。
在主要为黑人的学龄前儿童人群中，25-羟维生素D的中位数水平为28 ng/mL（四分位间距21.2 - 36.9），54%的儿童低于传统上认为充足的30 ng/mL水平，7.4%处于与佝偻病风险相关的范围（<15 ng/mL）。户外活动的中位数时间为每天3小时（四分位间距2 - 4），户外活动时间增加与更高的维生素D水平无关。在我们的队列中，25-羟维生素D没有显示出季节性变化（p = 0.66）。较低的25-羟水平与较高的IgE水平相关。
患有哮喘的城市非裔美国学龄前儿童维生素D不足的发生率很高，增加户外暴露不太可能纠正这些低水平的25-羟维生素D。在这一人群中补充维生素D可能需要膳食补充。
