Centre for Postgraduate Nursing Studies, University of Otago, Christchurch 8011, New Zealand.
Nutrition in Medicine Research Group, Department of Pathology & Biomedical Science, University of Otago, Christchurch 8011, New Zealand.
Nutrients. 2019 Sep 4;11(9):2102. doi: 10.3390/nu11092102.
Vitamin C is known to support immune function and is accumulated by neutrophils to millimolar intracellular concentrations suggesting an important role for the vitamin in these cells. In this review, the effects of vitamin C, as a mono- or multi-supplement therapy, on neutrophil function were assessed by conducting a systematic review of randomized controlled trials (RCTs). Specifically, trials which assessed neutrophil migration (chemotaxis), phagocytosis, oxidative burst, enzyme activity, or cell death (apoptosis) as primary or secondary outcomes were assessed. A systematic literature search was conducted using the Cochrane Central Register of Controlled Trials, EMBASE, Embase Classic, Joanna Briggs Institute EBP, Ovid MEDLINE, Ovid MEDLINE In-Process & Other Non-Indexed Citations, Ovid Nursing Database, CINAHL and PubMed database, which identified 16 eligible RCTs. Quality appraisal of the included studies was carried out using the Cochrane Risk of Bias tool. Three of the studies assessed neutrophil chemotaxis in hospitalised patients or outpatients, two of which showed improved neutrophil function following intravenous vitamin C administration. Ten RCTs assessed neutrophil phagocytosis and/or oxidative burst activity; five were exercise studies, one in smokers, one in myocardial infarction patients and three in healthy volunteers. Two of the multi-supplement studies showed a difference between the intervention and control groups: increased oxidative burst activity in athletes post-exercise and decreased oxidant generation in myocardial infarction patients. Two studies assessed neutrophil enzyme activity; one showed deceased antioxidant enzyme activity in divers and the other showed increased antioxidant enzyme activity in athletes. One final study showed decreased neutrophil apoptosis in septic surgical patients following intravenous vitamin C administration. Overall, 44% of the RCTs assessed in this review showed effects of vitamin C supplementation on neutrophil functions. However, the studies were very heterogeneous, comprising different participant cohorts and different dosing regimens. There were also a number of limitations inherent in the design of many of these RCTs. Future RCTs should incorporate prescreening of potential participants for low vitamin C status or utilize cohorts known to have low vitamin status, such as hospitalized patients, and should also comprise appropriate vitamin C dosing for the cohort under investigation.
维生素 C 已知可支持免疫功能，并被中性粒细胞积累至毫摩尔细胞内浓度，表明维生素在这些细胞中具有重要作用。在本综述中，通过系统评价随机对照试验（RCT）来评估维生素 C 作为单一或多种补充剂治疗对中性粒细胞功能的影响。具体而言，评估中性粒细胞迁移（趋化性）、吞噬作用、氧化爆发、酶活性或细胞死亡（凋亡）作为主要或次要结局的试验被评估。使用 Cochrane 中央对照试验注册库、EMBASE、Embase Classic、 Joanna Briggs 循证卫生保健研究所 EBP、Ovid MEDLINE、Ovid MEDLINE 处理中及其他非索引引文、Ovid 护理数据库、CINAHL 和 PubMed 数据库进行系统文献检索，共确定了 16 项合格的 RCT。使用 Cochrane 偏倚风险工具对纳入研究进行质量评估。其中 3 项研究评估了住院患者或门诊患者的中性粒细胞趋化性，其中 2 项研究表明静脉注射维生素 C 后中性粒细胞功能得到改善。10 项 RCT 评估了中性粒细胞吞噬作用和/或氧化爆发活性；其中 5 项为运动研究，1 项在吸烟者中进行，1 项在心肌梗死患者中进行，3 项在健康志愿者中进行。两项多补充剂研究显示干预组和对照组之间存在差异：运动后运动员的氧化爆发活性增加，心肌梗死患者的氧化剂生成减少。两项研究评估了中性粒细胞酶活性；一项显示潜水员的抗氧化酶活性降低，另一项显示运动员的抗氧化酶活性增加。最后一项研究表明，静脉注射维生素 C 后，败血症手术患者的中性粒细胞凋亡减少。总体而言，本综述评估的 RCT 中有 44% 显示维生素 C 补充对中性粒细胞功能有影响。然而，这些研究非常不同，包括不同的参与者队列和不同的剂量方案。许多 RCT 也存在固有的设计局限性。未来的 RCT 应在纳入研究前筛选潜在参与者的维生素 C 状态是否低下，或使用已知维生素状态低下的队列，如住院患者，并应针对研究中的队列进行适当的维生素 C 剂量。
