Sapporo Medical Journal

Abstract : Nigella sativa (NS) is a commonly used traditional medicine which has been shown to have anti-inflammatory and immunomodulatory properties especially thymoquinone. However, its supplementation in patients of clinical trials showed conflicting results. Objectives: To perform a meta-analysis regarding the effects of NS supplementation on immune-inflammatory parameters such as Th1, Th2, Th17, Treg, CD4, CD8, CD4/CD8 ratio. Methods: Relevant articles were systematically searched through PubMed/Medline, SCOPUS, and Google Scholar databases from inception until June 6, 2020. Information related to: author’s name and year, study location, target population, sample size, age of participants, number of participants in each groups, type and dose of NS supplements, study duration, and the main results were extracted from each study. To determine the effect estimates, data were assessed using fixed or random effect model. Results: 15 studies using 509 subjects were enrolled for meta-analysis. Our results found a significant reduction in Th17 cells (SMD -0.58 [-1.08, -0.34], p=0.02) following supplementation with NS. There was a significant increased in Treg cells (SMD 0.32 [0.01, 0.63], p=0.05) and CD4 (SMD 2.29 [0.27, 4.32], p=0.03) following NS supplementation. In addition, there was significantly higher ratio of CD4/CD8 (SMD 0.65 [0.30, 1.00], p=0.0003) following NS supplementation. Effects of NS on Th1 cells (SMD -0.04 [-0.56, 0.47], p=0.87), Th2 cells (SMD -0.08 [-0.49, 0.34], p=0.7