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Effects of black seed (Nigella sativa L.) on cardiometabolic indices in type 2 diabetic patients: A systematic review and meta-analysis of RCTs.

  • 2025-04-08
  • Complementary therapies in medicine 90
    • Mehdi Karimi
    • Samira Pirzad
    • Seyed Morteza Ali Pourfaraji
    • Fatemeh Maleki Sedgi
    • Bahar Darouei
    • Reza Amani-Beni
    • Kimia Kazemi
    • Reyhaneh Rabiee

Study Design

Type
Meta-Analysis
Population
T2DM patients
Methods
Meta-analysis of RCTs; random-effects model; subgroup analyses

Background

Black seed is known for its health benefits in traditional medicine. While recent studies suggest it may improve cardiometabolic health, its impact on type 2 diabetes mellitus (T2DM) remains unclear. This study aims to meta-analysis randomized controlled trials (RCTs) to assess the effects of black seed supplementation on cardiometabolic indices in T2DM patients.

Methods

Following PRISMA guidelines, a comprehensive database search was conducted up to January 2025, and data were extracted from relevant RCTs. Mean differences (MD) and standard deviations (SD) were analyzed using a random-effects model, heterogeneity was assessed, and publication bias was evaluated.

Results

The pooled meta-analysis of 16 RCTs showed that black seed supplementation significantly reduced fasting blood glucose (FBG) (MD: -21.43 mg/dL; p = 0.005), hemoglobin A1c (HbA1c) (MD: -0.44; p = 0.01), total cholesterol (TC) (MD: -18.80 mg/dL; p = 0.04) and low-density lipoprotein (LDL) (MD: -19.53 mg/dL; p = 0.003). No significant effects were observed for 2-hour postprandial glucose (2-hpp), fasting insulin, homeostatic model assessment (HOMA), triglycerides (TG), high-density lipoprotein (HDL), aspartate aminotransferase (AST), alanine aminotransferase (ALT), creatinine, and body weight, or body mass index (BMI). Subgroup analyses revealed that black seed supplementation effectively reduced FBG for longer than 8 weeks; additionally, HbA1c, HOMA, and LDL in higher doses (>1 g/day), shorter durations (≤8 weeks), and use of the oil form.

Conclusion

Black seed supplementation appears to significantly improve FBG, HbA1c, TC, and LDL levels in patients with T2DM. However, no significant effects were observed on other metabolic parameters, including insulin, TG, liver enzymes, kidney function, or body weight. These findings suggest that black seed may be a beneficial adjunct therapy for glycemic and lipid control in T2DM patients but require further research to confirm its broader metabolic effects.

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