The Effects of N-acetylcysteine on Inflammatory Markers and Homocysteine: A Systematic Review and Meta-analysis of Randomized Controlled Trials

Acetyl group in this molecule protects it from oxidation.2 The acetylation, also, facilities reduced polarity and tissue uptake.3 NAC has been reported to play a role in wide range of disorders, including HIV infection,4 cancer,2 chelation in metal toxicity,5 acetaminophen poisoning,6 Sjögrens syndrome,7 psychiatric disorders, sepsis, influenza,8 inflammatory bowel disease9-11 and cardiovascular disease (CVD).12 NAC has its therapeutic application due to its direct and indirect antioxidant and anti-inflammatory activity. Direct antioxidant effect of NAC occurs because of reaction with free radicals and interaction with reactive oxygen species (ROS), precisely with its free thiol group.13 The indirect antioxidant function of NAC is related to its role as glutathione (GSH) precursor, resulting in increase of intracellular GSH concentration, particularly in liver cells where it is an important intracellular antioxidant.14 Namely NAC acts mainly as the supply of cysteine for GSH synthesis. High-dose folic acid, vitamin В6 or В12, serine, or betaine cannot normalize hyperhomocysteinema in the individuals that are resistant to conventional treatment.19,20 However, it has been shown that administration of NAC orally or intravenously dramatically decreases Hcy levels.21-23 Nevertheless, the effects of NAC on circulating inflammatory markers and Hcy are controversial and no studies have been done to analyze the effects of NAC on both inflammatory biomarkers and Hcy. [...]the aim of this study was to perform a meta-analysis and summarize systematically the present evidence from RCTs concerning the effects of NAC on inflammatory markers and Hcy levels in various diseases. The following MeSH and text keywords were used to identify primary RCTs: intervention ("N-acetylcysteine" OR "NAC"), and parameters ["C-reactive protein (CRP)" OR "tumor necrosis factor-a (TNF-a)" OR "interleukin 6 (IL-6)" OR "homocysteine (Hcy).