Department of Nutritional Sciences, Faculty of Health and Medical Sciences,University of Surrey,Guildford,Surrey,UK.
Proc Nutr Soc. 2018 Aug;77(3):292-301. doi: 10.1017/S0029665117004104. Epub 2017 Dec 4.
Vitamin D is a unique nutrient. First, it acts as a pro-hormone and secondly, the requirement for vitamin D can be met by both endogenous synthesis from sunlight and by dietary sources. This complicates the determination of dietary requirements for vitamin D, which along with the definition of optimal vitamin D status, have been highly controversial and much debated over recent years. Adolescents are a population group at high risk of low vitamin D status, which is concerning given the important role of vitamin D, and calcium, in promoting normal bone mineralisation and attainment of peak bone mass during this rapid growth phase. Dietary vitamin D recommendations are important from a public health perspective in helping to avoid deficiency and optimise vitamin D status for health. However limited experimental data from winter-based dose-response randomised trials in adolescents has hindered the development of evidence-based dietary requirements for vitamin D in this population group. This review will highlight how specifically designed randomised trials and the approach adopted for estimating such requirements can lead to improved recommendations. Such data indicate that vitamin D intakes of between 10 and about 30 µg/d may be required to avoid deficiency and ensure adequacy in adolescents, considerably greater than the current recommendations of 10-15 µg/d. Finally this review will consider the implications of this on public health policy, in terms of future refinements of vitamin D requirement recommendations and prioritisation of public health strategies to help prevent vitamin D deficiency.
维生素 D 是一种独特的营养素。首先，它作为一种前激素起作用，其次，维生素 D 的需求可以通过阳光内源性合成和饮食来源来满足。这使得确定维生素 D 的膳食需求变得复杂，近年来，维生素 D 的最佳状态的定义也一直存在争议，备受争议。青少年是维生素 D 水平低的高风险人群，考虑到维生素 D 和钙在促进正常骨矿化和在这个快速生长阶段达到峰值骨量方面的重要作用，这令人担忧。从公共卫生的角度来看，膳食维生素 D 推荐量很重要，有助于避免缺乏并优化维生素 D 对健康的状态。然而，由于青少年基于冬季的剂量反应随机试验的实验数据有限，这阻碍了该人群群体中基于证据的维生素 D 膳食需求的发展。这篇综述将重点介绍专门设计的随机试验以及为此类需求进行估算的方法如何能够带来更好的建议。这些数据表明，青少年每天摄入 10 到约 30 微克维生素 D 可能是避免缺乏和确保充足的必需量，远远超过目前 10-15 微克/天的建议。最后，本综述将考虑这对公共卫生政策的影响，包括未来对维生素 D 需求建议的细化以及优先考虑公共卫生策略以帮助预防维生素 D 缺乏。
