
Black seeds, Black cumin, black caraway, black onion seed, kalonji
Nigella sativa is a flowering plant found throughout India, Arabia, and Europe. The seeds, commonly known as Black Seeds or Black Cumin, are used in cooking and in traditional medicine for inflammation, infection, and cancer. Constituents from Nigella sativa demonstrated immunomodulatory (1) (2) (11), antioxidant (15), antiparasitic (13) and hepatoprotective effects (14) in vitro and in animal studies. Nigella sativa seed, may be useful in the treatment of asthma (21), hypertension (5) (10) (22), rheumatoid arthritis (26), dyspepsia (27) and diabetes (28) in humans. Thymoquinone, a major constituent of Nigella sativa, exhibited anti-epileptic effects in children with refractory seizures (23). Nigella sativa may also relieve symptoms of allergic reactions (12), but allergic contact dermatitis was reported with topical use (19).
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Evidence also suggests that Nigella sativa has anticancer properties. The constituents of the seeds, including thymoquinone, reduced the growth and size of tumors in rats (4) (5) (6) (7) (8) (9) ; thymoquinone also enhanced the anticancer effects of doxorubicin in certain cancer cell lines (25). Nigella sativa oil, when injected, demonstrated a protective effect against tissue damage caused by radiation in rats (15). Human studies are lacking.
Adverse effects are rare, but high doses of Nigella sativa oil caused liver and kidney damage in rats (7).
Thymoquinone, one of the chief constituents of Nigella sativa oil has antioxidant effects and restored the levels of lactate dehydrogenase, glutathione, and SOD in animal models (6) (7) (9). This may explain Nigella sativa's hepatoprotective effects (3) (4). Studies have also shown that Nigella sativa oil has anti-inflammatory property by inhibiting cyclooxygenase and lipoxygenase (18). An in vitro study demonstrated that nigellone, a constituent of the crude extract of Nigella sativa seeds, inhibited histamine release from rat peritoneal mast cells (10) and may reduce allergy symptoms in humans (12). Nigella sativa decreased hypertension in rats possibly due to its diuretic effects (5). It was also shown to decrease uterine smooth muscle contractions (14).
The antioxidant effect is thought to protect tissues from radiation injury (15). However, it is not clear if this would also make radiation therapy less effective. Thymoquinone administered to mice reduced the incidence of stomach tumors (7). Possible mechanisms include inhibition of DNA synthesis (7), and promotion of apoptosis by inhibiting cell growth in G1 phase (8).
BOTTOM LINE: Black cumin seed has not been shown to treat cancer in humans.
Black cumin seed is used for cooking and in medicine in India, Arabia, and Europe. Laboratory studies have shown that some components have antioxidant and anti-inflammatory effects. Therefore, there is some speculation that black cumin seed may be useful in the treatment of cancer and protect against the side effects of radiation therapy, but these have been proven in humans. Early phase studies suggest that black cumin seed may help to control high blood pressure, asthma, diabetes, and rheumatoid arthritis.