Influence of vitamin D on non-communicable disease outcomes in South African schoolchildren: the ViDiKids-NCD sub-study

“非传染性疾病”（NCD）是一个用来描述任何不是由感染引起的疾病的术语。非传染性疾病在世界范围内变得越来越普遍，特别是在生活在南非等中低收入国家的不太富裕的城市居民中。大多数关于非传染性疾病的研究都集中在主要影响成年人的疾病上，如心脏病和癌症。然而，儿童也受到非传染性疾病的影响，包括导致骨折（骨折）的骨骼变薄和肌肉量减少。20%的南非城市学童在15岁之前经历过骨折，而英国只有13%。迫切需要找到一种改善儿童骨骼健康和肌肉质量的方法。低水平的维生素D（“阳光维生素”）在生活在不利的城市环境中的儿童中很常见，如开普敦周围的乡镇，由于户外时间减少，饮食不良和肥胖（导致维生素D储存在脂肪中，因此无法获得需要它的器官）。越来越多的研究表明，维生素D水平低可能是导致骨骼变薄和肌肉减少的一个危险因素。然而，目前还缺乏大规模的、经过良好管理的研究，以确定补充维生素D是否能增强儿童的骨骼和肌肉质量。我们已经在5400名开普敦学生中进行了一项mrc资助的大型临床试验（ViDiKids研究），以观察补充维生素D是否可以预防结核病。在这个应用程序中，我们提议进行一项子研究，我们将在400名儿童中测量额外的结果，包括骨密度、肌肉质量和身体健康，这些儿童也参加了主要的VidiKids试验。2)目的和目标本研究的目的是确定是否每周口服维生素D补充剂，3年，可以改善骨密度，肌肉质量和身体健康的儿童生活在开普敦附近的乡镇。我们将通过对400名儿童进行次级研究来实现这一目标。在子研究开始时，我们将测量参与者的骨密度、肌肉质量和身体健康。在研究人员的监督下，参与者将被随机分配接受每周剂量的维生素D或安慰剂（虚拟药物）。在研究结束时，我们将重复评估骨密度、肌肉质量和身体健康，并比较在过去3年中接受维生素D和安慰剂治疗的儿童的这些结果。3)潜在的应用和益处我们已经知道，儿童骨密度的改善可以降低骨折的风险：如果我们证明维生素D可以提高骨密度，那么就可以定期给儿童补充维生素D来预防骨折。全世界有10亿人维生素D水平不足：因此，我们的研究结果可能具有全球重要性。有几个群体可以从这项研究中受益。儿童可能会从一种廉价、安全的降低骨折风险的方法中受益；发现一种控制非传染性疾病的新工具可使公共卫生医生受益；医学研究人员可以从维生素D对儿童健康影响的新的科学见解中受益。

'Non-communicable disease' (NCD) is a term used to describe any illness that is not caused by infections. NCDs are becoming more common worldwide, particularly among less wealthy city-dwellers living in lower- and middle-income countries such as South Africa. Most research on NCDs focuses on illnesses that primarily affect adults, such as heart disease and cancer. However, children are also affected by NCDs including thinning of the bones leading to fractures (broken bones), and reduced muscle mass. 20% of urban South African schoolchildren suffer a bone fracture by the age of 15, compared with 13% in England. There is an urgent need to identify a way to improve bone health and muscle mass in children.Low levels of vitamin D ('the sunshine vitamin') are common among children living in disadvantaged urban environments such as the townships around Cape Town, due to decreased time outdoors, poor diets and obesity (which leads to vitamin D being stored in fat so that it is not available to the organs that need it). A growing body of research suggests that low levels of vitamin D may be a risk factor for developing thinning of the bones and reduced muscle mass. However, there is a lack of large, well-conducted research studies designed to find out whether vitamin D supplementation could strengthen children's bones and boost their muscle mass.We are already conducting a large MRC-funded clinical trial (the ViDiKids study) in 5,400 Cape Town schoolchildren to see if vitamin D supplementation can prevent TB. In this application, we propose to conduct a sub-study in which we will measure additional outcomes including bone density, muscle mass and physical fitness in a sub-set of 400 children who are also taking part in the main VidiKids trial.2) Aims and objectivesThe aim of this research is to determine whether a weekly vitamin D supplement, taken by mouth for 3 years, can improve bone density, muscle mass and physical fitness in children living in townships around Cape Town. We will achieve this by conducting a sub-study in 400 children. At the start of the sub-study we will measure participants' bone density, muscle mass and physical fitness. Participants will then be allocated to receive weekly doses of vitamin D or placebo (dummy medication) at random, supervised by study staff. At the end of the study we will repeat assessments of bone density, muscle mass and physical fitness, and compare these outcomes between children who received vitamin D vs placebo over the previous 3 years.3) Potential applications and benefitsWe already know that improvements in bone density in children translate into reduced risk of bone fractures: if we show that bone density is boosted by vitamin D, then supplements could be routinely given to children to prevent bone fractures. 1 billion people worldwide have inadequate vitamin D levels: results of our study could therefore have global importance.Several groups could benefit from the study. Children could benefit from the discovery of a cheap, safe method of reducing their risk of fractures; public health doctors could benefit from the discovery of a new tool for control of non-communicable diseases; and medical researchers could benefit from new scientific insights into the effects of vitamin D on children's health.