Impact of vitamin D supplementation on cardiometabolic risk in schoolchildren

描述（由申请人提供）：维生素D缺乏与心血管疾病的发展有关，据估计，目前有600万儿童缺乏维生素D。由于许多儿童很难达到美国儿科学会（American Academy of Pediatrics）提出的400 IU/d的新推荐摄入量，许多人建议补充维生素d是必要的。维生素D缺乏症在北纬地区、一些肤色较深的少数群体以及超重或肥胖人群中更为常见。在这些人群中，可能需要更高的补充剂量来维持最佳血清水平并预防心血管风险。拟议工作的总体目标是确定生活在北纬地区（42°z以上）的儿童适当的维生素D补充需求，以维持最佳血清25-羟基维生素D [25(OH)D]水平，并将心脏代谢风险降至最低。我们还将首次在一项随机对照试验中调查停止补充后血清25(OH)D和心脏代谢危险因素的变化。来自美国东北部高肥胖率的社会经济弱势和种族多样化社区的4 - 8年级儿童将被随机分配到400 IU， 1000 IU或2000 IU/d，从初冬开始为期6个月。血清25(OH)D和心脏代谢危险因素（血脂和血糖）将在补充前、3个月和6个月以及停止补充后6个月进行基线测量。肥胖、体育活动、维生素D的膳食摄入和阳光照射也将在这些时间进行评估。这项工作的结果将为关于维生素D补充的循证建议和指南的发展提供信息，以保持最佳的25(OH)D水平并降低心脏代谢风险。如果补充维生素D有可能改善儿童时期的心脏代谢风险，那么我们最终将能够降低儿童成年后患心血管疾病的风险。

DESCRIPTION (provided by applicant): Vitamin D deficiency has been linked to the development of cardiovascular disease and it is estimated that six million children are currently vitamin D deficient. As it is difficult for many children to consume the new recommended intake of 400 IU/d set forth by the American Academy of Pediatrics, many have suggested that vitamin D supplementation is necessary. Vitamin D deficiency is even more common in northern latitudes, amongst some minority groups with darker skin pigmentation, and in those who are overweight or obese. In these groups, higher supplemental doses may be needed to maintain optimal serum levels and to prevent cardiovascular risk. The overall objective of the proposed work is to determine the appropriate vitamin D supplementation requirements for children living at northern latitudes (above 42Z) to maintain optimal serum levels of 25-hydroxyvitamin D [25(OH)D] and minimize cardiometabolic risk. We will also investigate for the first time in a randomized controlled trial what happens to serum 25(OH)D and cardiometabolic risk factors after supplementation is discontinued. Fourth-eight grade children from socioeconomically disadvantaged and racially diverse communities with high obesity rates in the northeastern U.S. will be randomized to 400 IU, 1000 IU, or 2000 IU/d for six months starting in the early winter. Serum 25(OH)D and cardiometabolic risk factors (blood lipids and glucose) will be measured at baseline prior to supplementation, at 3- and 6-months, and then again 6 months following the discontinuation of supplementation. Adiposity, physical activity, dietary intake of vitamin D, and sun exposure will also be assessed at these times. Results of this work will inform the development of evidence-based recommendations and guidelines regarding vitamin D supplementation to maintain optimal 25(OH)D levels and to reduce cardiometabolic risk. If vitamin D repletion has the potential to improve the cardiometabolic risk profile during childhood, then we will ultimately be able to lower a child's risk of developing cardiovascular disease in adulthood.