PURPOSE Randomized Clinical Trials (RCTs) have provided varied and conflicting findings regarding the effect of N-acetylcysteine (NAC) on inflammatory biomarkers. This study was conducted to review existing literature to determine whether NAC supplementation can affect inflammatory biomarkers in adults. METHODS Bibliographic databases of Scopus, and PubMed were used for relevant papers published until October 2019. Results were reported as weighted mean differences (WMD) with 95% confidence intervals (CI) using multi-level models. Cochrane's Q and I-squared (I2) tests were used to determine heterogeneity among studies. RESULTS Twenty-four RCTs which include 1057 sample size were entered to analysis. NAC doses and intervention duration ranged from 400 to 2000 mg/d, and 1 to 80 weeks, respectively. Oral supplementation of NAC reduced serum level of C-reactive protein (CRP) [WMD: -0.61 mg/L, 95% CI: -1.18 to -0.03, P = 0.039, I2 = 79.6%], and interleukin-6 (IL-6) [WMD: -0.43 pg/mL, 95% CI: -0.69 to -0.17, P = 0.001, I2 = 89.3%]. However, the effect of oral NAC supplementation on other inflammatory biomarkers was nonsignificant. Dose-response investigation showed a non-linear association between oral NAC supplementation with CRP. CONCLUSION Oral NAC supplementation reduced serum level of CRP and IL-6, but did not affect other inflammatory biomarkers. Nevertheless, more RCTs seems to be required to explore how NAC in different dosage and different routes of administration can affect inflammatory biomarkers.

中文翻译：

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N-乙酰半胱氨酸对成人炎症生物标志物血清水平的影响。随机临床试验的系统评价和荟萃分析的结果


关于 N-乙酰半胱氨酸 (NAC) 对炎症生物标志物的影响，目的随机临床试验 (RCT) 提供了各种相互矛盾的发现。本研究旨在回顾现有文献，以确定补充 NAC 是否会影响成人的炎症生物标志物。方法 Scopus 和 PubMed 的书目数据库用于截至 2019 年 10 月发表的相关论文。使用多水平模型将结果报告为加权平均差 (WMD)，置信区间 (CI) 为 95%。 Cochrane 的 Q 和 I 平方 (I2) 检验用于确定研究之间的异质性。结果 24 项随机对照试验（包括 1057 个样本量）被纳入分析。 NAC 剂量和干预持续时间分别为 400 至 2000 mg/d 和 1 至 80 周。口服补充 NAC 可降低血清 C 反应蛋白 (CRP) 水平 [WMD：-0.61 mg/L，95% CI：-1.18 至 -0.03，P = 0.039，I2 = 79.6%] 和白细胞介素 6 (IL -6) [WMD：-0.43 pg/mL，95% CI：-0.69 至 -0.17，P = 0.001，I2 = 89.3%]。然而，口服 NAC 补充剂对其他炎症生物标志物的影响并不显着。剂量反应研究显示口服 NAC 补充剂与 CRP 之间存在非线性关联。结论 口服 NAC 补充剂可降低血清 CRP 和 IL-6 水平，但不影响其他炎症生物标志物。尽管如此，似乎还需要更多的随机对照试验来探索不同剂量和不同给药途径的 NAC 如何影响炎症生物标志物。