Effect of Zataria multiflora supplementation on pro- or anti-inflammatory markers: a systematic review and meta-analysis of randomized placebo-controlled trials

The aim of this study was to investigate the effectiveness of Zataria multiflora and carvacrol supplementation on inflammatory markers (IL-2, IL-4, IL-5, IL-6, TNF-alpha, IL-8, IL-10, interferon gamma (IFN-gamma), C-reactive protein (CRP), monocyte chemotactic protein 1 (MCP-1), epidermal growth factor (EGF), and vascular endothelial growth factor (VEGF)) by conducting a systematic review and meta-analysis of randomized controlled trials (RCTs).The exploration of literature was conducted until August 2024 on databases like PubMed/Medline, Web of Science, Scopus, Cochrane CENTRAL, and Google Scholar. The current study incorporated trial studies examining how oral supplements of Zataria multiflora and carvacrol impact concentrations of inflammatory markers. By utilizing a random effects model, the mean differences (SMD) and 95% confidence intervals (CI) were pooled for analysis of the results. The Cochrane Q and I2 values were used to evaluate heterogeneity. The meta-analysis included ten cases, with 562 participants in the Zataria multiflora group and 700 in the control group. A significant decrease in the levels of various cytokines including IL-2, IL-4, IL-5, IL-6, IL-8, CRP, EGF, VEGF, and MCP-1 was observed with the consumption of Zataria multiflora along with a noteworthy increase in both IFN-gamma and IL-10. However, TNF-alpha levels remained unaffected by the intervention involving Zataria multiflora and carvacrol. It should be noted that limitations of this study include the fact that it draws from research in Iran, encompasses a range of different diseases, and overlooks potential confounders like smoking, physical activity, and diet. In summary, the results suggested that Zataria multiflora and carvacrol can be beneficial for reducing inflammation.