Food Security Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
Department of Community Nutrition, School of Nutrition and Food Science, Isfahan University of Medical Sciences, Isfahan, Iran.
Eur J Clin Nutr. 2018 Aug;72(8):1071-1082. doi: 10.1038/s41430-017-0048-z. Epub 2017 Dec 29.
BACKGROUND/OBJECTIVES: Conjugated linoleic acid (CLA) is a polyunsaturated fatty acid with attractive biological activities. Numerous studies have been conducted on the inflammation-lowering effects of CLA in in vitro and animal models. However, the effects of CLA treatment on the inflammatory markers in humans are controversial. Therefore, the objective of this study was to perform a systematic review and meta-analysis on controlled clinical trials (RCT) assessing the effects of CLA supplementation on the circulating inflammatory markers, including C-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α).
SUBJECTS/METHODS: The literature search of RCTs was performed using Pubmed/Medline, Scopus, ScienceDirect, Web of science, Cochrane, and Google Scholar databases from inception to March 2017. Weighted mean differences were estimated and the pooled effect size was calculated by a random effects model.
Of the 427 identified studies, eleven RCTs, including 420 subjects were included in the statistical analysis. Findings suggested that CLA supplementation increased blood levels of CRP by 0.89 mg/l (95% CI: 0.11, 1.68; P = 0.025) and TNF-α levels by 0.39 pg/ml (95% CI: 0.23, 0.55; P < 0.0001). However, blood IL-6 levels were marginally decreased by 0.32 pg/ml (95% CI: -0.71, 0.07; P = 0.11) following CLA supplementation. There was a significant heterogeneity for the impact of CLA on CRP and IL-6, but not TNF-α.
This meta-analysis showed that CLA supplementation may increase inflammatory markers (CRP and TNF-α). There are concerns about using CLA supplementation as an anti-obesity agent among the obese population for at least a short duration.
背景/目的：共轭亚油酸（CLA）是一种具有吸引力的生物活性的多不饱和脂肪酸。已有大量研究探讨 CLA 在体外和动物模型中降低炎症的作用。然而，CLA 治疗对人体炎症标志物的影响存在争议。因此，本研究旨在对评估 CLA 补充剂对循环炎症标志物（包括 C 反应蛋白（CRP）、白细胞介素-6（IL-6）和肿瘤坏死因子-α（TNF-α）的影响的对照临床试验（RCT）进行系统评价和荟萃分析。
受试者/方法：使用 Pubmed/Medline、Scopus、ScienceDirect、Web of science、Cochrane 和 Google Scholar 数据库从建库至 2017 年 3 月对 RCT 进行文献检索。使用随机效应模型估计加权均数差，并计算合并效应量。
在 427 项已识别的研究中，有 11 项 RCT 包括 420 名受试者被纳入统计分析。研究结果表明，CLA 补充剂使 CRP 血液水平升高 0.89mg/L（95%CI：0.11，1.68；P=0.025），TNF-α 水平升高 0.39pg/ml（95%CI：0.23，0.55；P<0.0001）。然而，CLA 补充后 IL-6 血液水平降低了 0.32pg/ml（95%CI：-0.71，0.07；P=0.11）。CLA 对 CRP 和 IL-6 的影响存在显著异质性，但对 TNF-α 无显著异质性。
本荟萃分析表明，CLA 补充剂可能会增加炎症标志物（CRP 和 TNF-α）。在肥胖人群中，CLA 补充剂作为短期抗肥胖药物的使用存在担忧。
