Why does garlic make your breath smell?


THAT'S THE WHY:We’ve all been there. Stuck at close quarters with someone who has recently feasted on garlic-rich fare, or perhaps mortified when you start up a conversation and realise a moment too late that your own breath might carry more than a tinge of the reeky vegetable.

Garlic may be tasty and good for your health, but why is it so bad for your breath – or at least for the people nearby when you are breathing out?

The gastronomic bulb’s smelly after-effects come from its richness in sulphur-containing compounds, and a study back in 1999 went to great lengths to identify and track the anti-social garlic-derived molecules.

Five healthy volunteers were asked to eat 6gms of raw garlic, then the researchers collected and analysed samples of urine as well as air from the mouth and lungs over time.

Air taken from the mouth contained increased levels of many sulphur-containing gases for up to three hours after eating garlic, and in practice brushing the teeth could reduce their odour.

But one compound was more persistent: allyl methyl sulfide turned up in the mouth air, the lung air and the urine, suggesting it had been absorbed from the gut and was being offloaded and exhaled through the lungs.

“Breath odour after garlic ingestion initially originates from the mouth and subsequently from the gut,” stated the authors in the American Journal of Physiology.

That’s something to bear in mind in the run-up to that job interview, long-haul flight or hot date.