JAMA:维生素D补充剂不会降低感冒的发病率或严重程度

据发表在10月3日刊《美国医学会杂志》上的一项研究披露，尽管某些数据显示在血清维生素D浓度与上呼吸道感染（感冒）之间可能存在着一种负相关，但某个随机控制试验的参与者中的那些接受一个月度剂量的维生素D3达10,0000 IUs的人的感冒发生率或严重程度并没有显著地下降。

根据文章的背景资料，维生素D不足与呼吸道病毒感染易感性之间的关系一直不清楚。

新西兰克赖斯特彻奇市奥塔哥大学的David R. Murdoch, M.D.及其同事开展了一项随机性试验，旨在检查维生素D补充剂在健康的成年人中对上呼吸道感染（URTIs）的发病率及严重程度的影响。这项在2010年2月至2011年11月间开展的研究包括了在新西兰的322名健康的成年人。参与者被随机指派接受最初的20,0000 IU的口服维生素D3并接着在1个月后服用20,0000 IU的维生素D3，然后再每个月服用10,0000 IU (n = 161)；或者以完全等同的给药方式服用安慰剂达18个月（n = 161）。

在研究开始的时候，参与者的25-羟基维生素D（25-OHD）的平均浓度水平为29 ng/mL。服用维生素D补充剂导致血清25-OHD浓度增加并在整个研究中被维持在大于48 ng/mL的水平。服用维生素D组中共发生了593起URTI，安慰剂组则发生了611起URTI。

研究人员发现，每位参与者的URTIs次数（平均来说，维生素D组每人发生3.7次URTIs，安慰剂组每人发生3.8次的URTIs）、每次发作时症状的持续时间（平均来说每个小组的发作时间为12天）、因为URTIs而误工的天数或URTI发作时的严重程度上不存在统计学上的显著差异。文章的作者写道：“这项研究的主要发现是，给予健康成年人每月10,0000 IU的维生素D3的剂量不会显著地降低其URTIs的发病率或严重性。在该分析中纳入冬季或基线25-OHD浓度时这一结果仍然没有变化。人们需要做进一步的研究来厘清在其他人群中给予该补充剂或用其它的给药方式时是否会有裨益。”

与维生素D相关的拓展阅读：

• ARD：维生素D可通过增强线粒体功效使肌肉充满能量
• BMJ ：易感染患者服用维生素D或可避免呼吸道感染
• JCSM：维生素D缺乏易导致白天容易瞌睡
• Diabetologia：维生素D缺乏与1型糖尿病
• JBC：维生素D或可抑制糖尿病患者动脉的阻塞
• CMAJ：低水平的维生素D或与家族长寿直接相关
更多信息请点击：有关维生素D更多资讯

Effect of vitamin D3 supplementation on upper respiratory tract infections in healthy adults: the VIDARIS randomized controlled trial

CONTEXT: Observational studies have reported an inverse association between serum 25-hydroxyvitamin D (25-OHD) levels and incidence of upper respiratory tract infections (URTIs). However, results of clinical trials of vitamin D supplementation have been inconclusive.

OBJECTIVE: To determine the effect of vitamin D supplementation on incidence and severity of URTIs in healthy adults.

DESIGN, SETTING, AND PARTICIPANTS: Randomized, double-blind, placebo-controlled trial conducted among 322 healthy adults between February 2010 and November 2011 in Christchurch, New Zealand.

INTERVENTION: Participants were randomly assigned to receive an initial dose of 200,000 IU oral vitamin D3, then 200,000 IU 1 month later, then 100,000 IU monthly (n = 161), or placebo administered in an identical dosing regimen (n = 161), for a total of 18 months.

MAIN OUTCOME MEASURES: The primary end point was number of URTI episodes. Secondary end points were duration of URTI episodes, severity of URTI episodes, and number of days of missed work due to URTI episodes.

RESULTS: The mean baseline 25-OHD level of participants was 29 (SD, 9) ng/mL. Vitamin D supplementation resulted in an increase in serum 25-OHD levels that was maintained at greater than 48 ng/mL throughout the study. There were 593 URTI episodes in the vitamin D group and 611 in the placebo group, with no statistically significant differences in the number of URTIs per participant (mean, 3.7 per person in the vitamin D group and 3.8 per person in the placebo group; risk ratio, 0.97; 95% CI, 0.85-1.11), number of days of missed work as a result of URTIs (mean, 0.76 days in each group; risk ratio, 1.03; 95% CI, 0.81-1.30), duration of symptoms per episode (mean, 12 days in each group; risk ratio, 0.96; 95% CI, 0.73-1.25), or severity of URTI episodes. These findings remained unchanged when the analysis was repeated by season and by baseline 25-OHD levels.

CONCLUSION: In this trial, monthly administration of 100,000 IU of vitamin D did not reduce the incidence or severity of URTIs in healthy adults.