Black seed oil: what the thymoquinone number actually means

Black seed oil has been used in this region for centuries, but the market is now full of bottles that share a name and nothing else. The difference comes down to one compound and one number.

Thymoquinone is the point

Nigella sativa seed contains a volatile compound called thymoquinone, usually written TQ. Almost all of the research interest in black seed comes back to it. Good cold pressed oil carries roughly 0.4% to 0.8% TQ.

Why heat destroys it

Thymoquinone is heat sensitive. A commercial expeller press generates enough friction heat to push the seed past 90°C, and the refining, bleaching and deodorising that usually follows removes most of what is left. The oil that comes out is pale, smooth and nearly tasteless.

That is why the throat burn matters. If your kalojira oil goes down like cooking oil, the compound you bought it for is probably not in the bottle.

What to check before you buy

• Press method: cold pressed under 40°C, stated clearly
• TQ content: a real number, not just the words "high thymoquinone"
• Free fatty acid: under 2% indicates fresh, well-stored seed
• Bottle: amber or dark glass, never clear plastic
• Sediment: a little settling is a good sign of unfiltered oil

How to take it

Half a teaspoon twice a day is the traditional dose for adults, usually with honey or warm water to soften the bite. Never cook with it — you would be undoing the entire point of a cold press. Store away from sunlight and use within six months of opening.

Who should be careful

Anyone on blood pressure or diabetes medication should speak to their doctor first, since black seed may add to the effect of those drugs. It is a food, but it is a potent one.