Bad breath gene discovered

Remember when you used to breathe out into your cupped hand to smell your breath in case it was bad? Well, it may not be your food, your poor oral hygiene or an upset stomach. It could be your genes.

An international team of researchers has identified a genetic cause for chronic bad breath (halitosis). While most cases of bad breath are linked to bacteria growing in the mouth, up to 3% of the population have chronic halitosis with no obvious cause.

Researchers at Radboud University in The Netherlands have been studying families with chronic bad breath for several years. They found these people produced a lot of sulphur compounds in their breath, especially methanethiol, which has an unpleasant boiled cabbage smell.

But some bacteria can break down sulphur compounds. Based on bacterial genes, the team identified a human protein which can change methanethiol into odourless compounds.

When they looked at their patients, they found all had mutations of a particular gene (SELENBP1) that produces this protein and they all had high levels of methanethiol in their blood.

When blood reaches the lungs, the smelly sulphur compounds escape and are exhaled in breath.

Professor Kent Lloyd, one of the study’s authors, said: “It’s important to identify the cause of persistent halitosis and differentiate that cause from relatively benign causes (e.g. gum disease) and the more morbid causes such as liver cirrhosis.”

Currently there’s no treatment for this form of halitosis, but the genetic studies and a better understanding of sulphur metabolism could lead to treatments in the future.

But now at least you’ve got an excuse when someone complains to you that you’ve got bad breath.

Just say, sorry, it’s in my genes.