AUTHOR=Li Zhongyu , Wang Yang , Xu Qing , Ma Jinxin , Li Xuan , Yan Jiaxing , Tian Yibing , Wen Yandong , Chen Ting 

TITLE=Nigella sativa and health outcomes: An overview of systematic reviews and meta-analyses

JOURNAL=Frontiers in Nutrition

VOLUME=10

YEAR=2023

URL=https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2023.1107750

DOI=10.3389/fnut.2023.1107750

ISSN=2296-861X

ABSTRACT=<sec><title>Background</title><p><italic>Nigella sativa</italic> (<italic>N. sativa</italic>) consumption has been associated with various health outcomes; however, the results are not completely consistent.</p></sec><sec><title>Objectives</title><p>This overview of systematic reviews and meta-analyses aimed to evaluate the reporting and methodological quality, and to grade the available evidence of associations between <italic>N. sativa</italic> and health outcomes.</p></sec><sec><title>Methods</title><p>PubMed, Cochrane Library, Embase, and Scopus databases were searched from their inception to September 30, 2022. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2009 statement, Assessment of Multiple Systematic Reviews (AMSTAR) 2 checklist, and Grades of Recommendations, Assessment, Development and Evaluations (GRADE) systems were used to assess the reporting, methodological, and evidence quality for each meta-analysis, respectively. The results were synthesized in a narrative form.</p></sec><sec><title>Results</title><p>This overview included 20 eligible meta-analyses published in peer-reviewed journals between 2013 and 2021. The overall methodological quality was relatively poor, with only one moderate quality, four low quality, and 15 critically low quality studies. For reporting quality, items two, five, eight, nine, 15, and 24 need to improve. Among the 110 outcome indicators of the quality of evidence, five were graded as moderate, 17 as low, and 88 as very low. Risk of bias, inconsistency, and imprecision were the main downgrading factors.</p></sec><sec><title>Conclusion</title><p>This overview suggests that <italic>N. sativa</italic> is beneficial for various clinical outcomes. However, there are certain limitations to reporting and methodological quality. The clinical efficacy of <italic>N. sativa</italic> requires confirmation in high-quality, large-sample, randomized controlled trials.</p></sec>