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Evidence-Based Supplement Research
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Black Cumin and Reduced Fasting Blood Glucose Levels

Research synthesisHigh evidenceMixed effect size8 studies · 7 beneficial · 1 neutral · 0 harmful

Across 8 studies, 7 reported beneficial effects of black cumin (Nigella sativa) on reducing fasting blood glucose levels, with effect sizes ranging from small to large. The most robust evidence comes from meta-analyses and RCTs, including a large 2025 meta-analysis (n=5026) that found moderate beneficial effects, while several recent meta-analyses reported large effect sizes in clinical populations such as those with type 2 diabetes or metabolic syndrome. The median study duration was 32 days, with doses reported in two studies ranging from 200 to 4600 mg/day.

  • Effective dose range: 200 to 4600 mg/day (based on 2 of 8 studies reporting dose)
  • Studied populations: adults with type 2 diabetes, coronary artery disease, metabolic syndrome, and general adults

Caveats: Available evidence is overwhelmingly positive — clinical literature in this area is subject to publication bias (null-result studies are less likely to be published or indexed). Most studies lacked data on supplement form, making it unclear if specific preparations (e.g., oil, powder) are more effective. The heterogeneity in effect sizes (small to large) across studies partly reflects differences in populations and dosages.

Generated Jul 16, 2026
Doses used in studies
  • g/day: 2 (median 2, IQR 2–2) — 1 study
  • mg/day: 200–4,600 (median 2,400, IQR 200–4,600) — 1 study
Time to effect
Median: 4.5 weeks · IQR 2.8 weeks–6.3 weeks · Range 7 days–8 weeks — Reported in 2 of 8 studies
8 of 8 papers
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