The Effect of Nigella Sativa on Cardio-Metabolic Parameters: A Protocol for A Systematic Review and Meta-Analysis

Background: Among non-communicable diseases, cardiovascular diseases (CVDs) account for 44% of all deaths. Among natural alternatives, Nigella sativa (NS) exert beneficial effects on cardio-metabolic factors. This is the first systematic review and meta-analysis protocol aimed to identify all the findings relevant to the effects of NS on cardio-metabolic factors among adults. Methods: This study was prepared according to PRISMA-P checklist based on Cochrane Handbook for Systematic Reviews of Interventions. An initial literature search was conducted in various databases using MeSH terms and related synonyms. Trials examining the effects of NS versus control group were included. Main outcomes consisted of blood pressure, lipid and glycemic factors, and atherogenic indices. Seven reviewers independently evaluated titles and abstracts, reviewed full texts, extracted information, and assessed the risk of bias. Methodological quality of each randomized controlled trial was assessed using the Cochrane Handbook and the GRADE system, while Newcastle-Ottawa Quality Assessment Scale was used for non-randomized studies. Continuous data of homogeneous studies were meta-analyzed via STATA. Mean differences were calculated as the effect size with 95% CIs. Heterogeneity assessment, sensitivity analysis, and publication bias were performed. Conclusion: The quality of both randomized and non-randomized studies was assessed. The evidence from this study can provide information for future clinical trials