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Evidence-Based Supplement Research
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Black Cumin and Reduced Hemoglobin A1c

Research synthesisHigh evidenceModerate effect6 studies · 5 beneficial · 1 neutral · 0 harmful

Across 6 studies, 5 reported beneficial effects of black cumin (Nigella sativa) on reducing hemoglobin A1c (HbA1c), with predominantly moderate effect sizes. The most-studied populations include adults with type 2 diabetes (T2DM) or metabolic syndrome, with a wide dose range (200 to 4600 mg/day). Only 1 of 6 studies reported a duration (7 days), making conclusions about typical treatment length uncertain.

  • Effective dose range: 200 to 4600 mg/day
  • Studied populations: adults with type 2 diabetes (T2DM), patients with metabolic syndrome

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). Median study duration is only 7 days (reported in 1 study), so the observed effects may not reflect long-term outcomes typically needed for HbA1c changes. Most studies are meta-analyses with moderate to high heterogeneity, and one neutral study (2024 meta-analysis) noted limited improvement in T2DM subjects overall.

Generated Jul 13, 2026
Doses used in studies
  • mg/day: 200–4,600 (median 2,400, IQR 200–4,600) — 1 study
Time to effect
Median: 7 days · IQR 7 days–7 days · Range 7 days–7 days — Reported in 1 of 6 studies
6 of 6 papers
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