Black cumin

Nigella sativa is an annual herb with finely divided leaves and pale blue or white flowers. After flowering it forms an inflated, many-chambered capsule that holds numerous small seeds.

The seeds are matte black, about two millimetres long, angular with a wrinkled surface, and they look like tiny, flattened pyramids. Their flavour is sharp, peppery and slightly bitter with hints of onion, oregano and mild smoke, and they smell aromatic when toasted.

They are sold whole, ground, and as cold-pressed oil, and are often sold under the name kalonji. They are unrelated to true cumin despite the common name.

Nigella sativa is thought to be native to southwest Asia and the Mediterranean region, though the exact limits of its wild range are unclear because it has been cultivated for so long. It grows today in Middle Eastern, South Asian, North African and Eastern European regions.

Archaeological finds, including seeds in ancient Egyptian contexts such as the tomb of Tutankhamun, show its use in antiquity.

The genus name Nigella derives from the Latin niger meaning black, and sativa means cultivated. The English name black cumin is a loose reference to the seed colour and is confusingly applied to other spices as well.

Black cumin has been valued for more than three thousand years. Nigella seeds have been found in ancient Egyptian contexts, and classical writers such as Pliny and Dioscorides mention a Nigella-like plant as a seasoning and medicine.

In the Islamic world, a saying attributed to the Prophet Muhammad that the black seed is a remedy for every disease except death raised its prestige, giving it the Arabic name habbat al-barakah, the seed of blessing, and encouraging a long tradition of use in Unani and Arab medicine.

The spice is part of Indian panch phoron, the Bengali five-spice blend, as well as of Turkish and Armenian breads and of Ethiopian spice blends.

In the late 20th and early 21st century, black seed oil became a global supplement and natural product, supported by thousands of laboratory and animal studies, with much smaller numbers of human trials.

The seeds are sprinkled on naan, Turkish pide and simit, Armenian string cheese and flatbreads, or used in pickles and vegetable curries. They are one of the five spices in Bengali panch phoron and are often fried briefly in oil to release flavour.

Honey with black seed and cold-pressed black seed oil are taken in many Middle Eastern and South Asian households as a traditional tonic.

The seeds are also ground into spice mixes, steeped in tea, and used in cosmetics and hair oils.

Black cumin contains thymoquinone and other compounds that have been studied for antioxidant, anti-inflammatory and blood sugar-related effects. Some small clinical trials and meta-analyses suggest modest improvements in blood glucose, cholesterol or blood pressure, but trial quality and dose vary, and results are not conclusive.

Claims that it cures major diseases are not supported by high-quality evidence. Used as a spice, it is a safe flavouring, and supplements should be treated cautiously.