The effects of alpha-lipoic acid supplementation on inflammatory markers among patients with metabolic syndrome and related disorders: a systematic review and meta-analysis of randomized controlled trials

Objective: This systematic review and meta-analysis of randomized controlled trials (RCTs) was conducted to determine the effect of alpha-lipoic acid (ALA) supplementation on the inflammatory markers among patients with metabolic syndrome (MetS) and related disorders. Methods: We searched the following databases until November 2017: PubMed, MEDLINE, EMBASE, Web of Science, and Cochrane Central Register of Controlled Trials. Three reviewers independently assessed study eligibility, extracted data, and evaluated risk of bias of included primary studies. Statistical heterogeneity was assessed using Cochran's Q test and I-square (I-2) statistic. Data were pooled by using the random-effect model and standardized mean difference (SMD) was considered as the summary effect size. Results: Eighteen trials out of 912 potential citations were found to be eligible for our meta-analysis. The findings indicated that ALA supplementation significantly decreased C-reactive protein (CRP) (SMD = -1.52; 95% CI, -2.25, -0. 80; P < 0.001), interlokin-6 (IL-6) (SMD = -1.96; 95% CI, -2.60, -1.32; P < 0.001), and tumor necrosis factor alpha levels (TNF-alpha) (SMD=-2.62; 95% CI, -3.70, -1.55; P < 0.001) in patients diagnosed with metabolic diseases. Conclusion: In summary, the current meta-analysis demonstrated the promising impact of ALA administration on decreasing inflammatory markers such as CRP, IL-6 and TNF-alpha among patients with MetS and related disorders.