Supplement analysis backed by scientific evidence · PT

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Moderate evidenceHeart & metabolic

Black Seed Oil (Nigella)

Nigella sativa has surprisingly consistent meta-analytic support for small reductions in blood pressure, fasting glucose and LDL-cholesterol. Effects are real but modest, and trial quality is generally low with most studies from a handful of regions.

What the science says

  • Lowers blood pressure modestly Moderate evidence

    A meta-analysis of 11 randomized trials found Nigella sativa reduced systolic blood pressure by about 3.3 mmHg and diastolic by about 2.8 mmHg versus placebo. Short-term powdered seed preparations produced larger systolic effects than the oil, and follow-up was mostly 8-12 weeks.

  • Improves glycemic and lipid markers in prediabetes and type 2 diabetes Moderate evidence

    A meta-analysis of randomized trials in prediabetes and type 2 diabetes reported reductions in fasting blood glucose and HbA1c along with lower total cholesterol, LDL and triglycerides. Effect sizes were modest and heterogeneity was high, so this is an adjunct rather than a replacement for metformin or statins.

  • Asthma, allergy and immune claims Limited evidence

    Small trials in allergic rhinitis and asthma report symptom improvements, but samples are tiny, blinding is often inadequate, and thymoquinone content varies enormously between products. Treat these uses as unproven.

Dosage & safety

Studied doseTrials used 0.5-3 g/day of black seed oil, or 1-3 g/day of powdered seed, for 8-12 weeks. Standardized products list thymoquinone content (commonly 0.5-3%), which is the main active constituent and varies widely by brand.
SafetyCommonly causes nausea, reflux and abdominal discomfort. Contact dermatitis from topical use is well documented. Because it lowers blood pressure and glucose, it can compound the effect of antihypertensives and antidiabetic drugs — monitor for hypotension and hypoglycemia. Thymoquinone inhibits CYP enzymes and P-glycoprotein in vitro, so interactions with narrow-therapeutic-index drugs (warfarin, cyclosporine) are plausible. Avoid in pregnancy: high doses have shown uterine-relaxant and antifertility effects in animals. Products vary hugely in potency; buy from brands that publish third-party testing.

Scientific references

Where to buy

Amazing Herbs, Premium Black Seed™, 100% Pure Cold-Pressed Black Cumin Seed Oil, 8 fl oz (240 ml)

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