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Black Seed

Nigella sativa

Black seed (also called black cumin or kalonji) has a long tradition in Middle Eastern, North African and South Asian households. Many small trials point to modest effects on blood sugar, cholesterol and blood pressure, but the quality of that research is low.

What it is

Nigella sativa is a small flowering plant. Its tiny black seeds taste peppery and slightly bitter and are sprinkled on breads and pickles. The main studied compound is thymoquinone, found in the seed oil.

Supplements come as whole-seed powder, cold-pressed oil or extract. Most studies used oil or powder; our capsule is whole-seed powder.

What the research says

Blood sugar (HbA1c, fasting glucose)

Mixed

Most meta-analyses report reductions, but an overview of 20 meta-analyses rated nearly all the evidence low or very low quality.

Cholesterol

Mixed

Total and LDL cholesterol fell in most pooled analyses; HDL mostly did not change.

Blood pressure

Mixed

Both meta-analyses that looked at it found modest reductions.

Amounts used in studies

Trials used 0.5–6 g of seed or powder a day, or 2.5–5 ml of oil, for two weeks to a year.

Who should avoid it

  • Pregnancy — traditional sources describe it as a uterine stimulant.
  • Low blood pressure or low blood sugar.
  • The two weeks before surgery.

Medicines to watch

  • Diabetes medicines: monitor for low blood sugar.
  • Blood-pressure medicines: may add to their effect.
  • Blood thinners: possible added bleeding risk.

What to look for when buying

  • Make sure it is Nigella sativa. "Black cumin" is also used for Bunium bulbocastanum, a different plant.
  • Seed powder oxidises; buy small batches and store sealed.

Common questions

Is black seed the same as black cumin?

Often, yes — but the name is used for two plants. Check for Nigella sativa on the label.

Oil or powder?

Oil concentrates thymoquinone; whole-seed powder also carries fibre and protein. Both have been studied.

Sources

  1. Nigella sativa and health outcomes: overview of meta-analyses (Frontiers in Nutrition, 2023)

Last reviewed 19 October 2026 by Spicewell editorial team. How we write our guides

This guide is general information, not medical advice. Speak to a doctor or pharmacist before starting any supplement, especially if you are pregnant, breastfeeding, under 18 or taking medication.