Human Nutrition Research Centre, Institute of Cellular Medicine, Newcastle University, Campus for Ageing and Vitality, Newcastle, UK.
College of Medicine, University of Al-Mustansiriyah, Baghdad, Iraq.
Eur J Clin Nutr. 2017 Dec;71(12):1371-1380. doi: 10.1038/ejcn.2017.24. Epub 2017 Mar 15.
Randomised controlled trials (RCTs) have observed contrasting results on the effects of vitamin C on circulating biomarkers of glycaemic and insulin regulation. We conducted a systematic review and meta-analysis of RCTs testing the effect of vitamin C administration on glucose, HbA1c and insulin concentrations. Four databases (PubMed, Embase, Scopus and Cochrane Library) were used to retrieve RCTs published from inception until April 2016 and testing the effects of vitamin C in adult participants. The screening of 2008 articles yielded 22 eligible studies (937 participants). Overall, vitamin C did not modify glucose, HbA1c and insulin concentrations. However, subgroup analyses showed that vitamin C significantly reduced glucose concentrations (-0.44 mmol/l, 95% CI: -0.81, -0.07, P=0.01) in patients with type 2 diabetes and in interventions with a duration greater than 30 days (-0.53%, 95% CI: -0.79, -0.10, P=0.02). Vitamin C administration had greater effects on fasting (-13.63 pmol/l, 95% CI: -22.73, -4.54, P<0.01) compared to postprandial insulin concentration. Meta-regression analyses showed that age was a modifier of the effect of vitamin C on insulin concentration. Furthermore, the effect size was associated with baseline BMI and plasma glucose levels, and with the duration of the intervention. In conclusion, greater reduction in glucose concentrations observed in patients with diabetes, older individuals and with more prolonged supplementation. Personalised interventions with vitamin C may represent a feasible future strategy to enhance benefits and efficacy of interventions. Nevertheless, results need to be interpreted cautiously due to limitations in the primary studies analysed.
随机对照试验（RCT）已经观察到维生素 C 对血糖和胰岛素调节的循环生物标志物的影响存在相互矛盾的结果。我们对测试维生素 C 给药对葡萄糖、HbA1c 和胰岛素浓度影响的 RCT 进行了系统评价和荟萃分析。使用四个数据库（PubMed、Embase、Scopus 和 Cochrane Library）检索从成立到 2016 年 4 月发表的 RCT，并测试成年参与者中维生素 C 的效果。筛选了 2008 篇文章，得到了 22 项合格的研究（937 名参与者）。总体而言，维生素 C 并未改变葡萄糖、HbA1c 和胰岛素浓度。然而，亚组分析表明，维生素 C 可显著降低 2 型糖尿病患者的血糖浓度（-0.44mmol/l，95%CI：-0.81，-0.07，P=0.01）和干预持续时间超过 30 天的患者的血糖浓度（-0.53%，95%CI：-0.79，-0.10，P=0.02）。与餐后胰岛素浓度相比，维生素 C 给药对空腹胰岛素浓度的影响更大（-13.63pmol/l，95%CI：-22.73，-4.54，P<0.01）。Meta 回归分析表明，年龄是维生素 C 对胰岛素浓度影响的调节剂。此外，效应大小与基线 BMI 和血浆葡萄糖水平以及干预持续时间相关。总之，在糖尿病患者、年龄较大的患者和接受更长期补充的患者中观察到血糖浓度的降低更大。个性化的维生素 C 干预可能代表一种可行的未来策略，可以提高干预的效益和效果。然而，由于分析的主要研究存在局限性，结果需要谨慎解释。
