Bad breath beware

Adding a pinch of magnolia bark to mints or gum can eliminate bad breath by killing most odour-causing germs, US researchers have reported.

Most bad breath occurs when bacteria in the mouth break down proteins, producing foul-smelling sulfur compounds. But many anti-bacterial agents cause nasty side effects like tooth staining, making them impractical for oral care.

Magnolia bark extract - a traditional Chinese medicine used to treat fever, headache and stress - has proven effective against germs that cause ulcers, and recent studies have shown it has low toxicity and few side effects.

Scientists at chewing gum maker Wm Wrigley Jr Co wanted to see if it could kill halitosis-causing bacteria, and if it could be used in a gum or mint.

Researchers Minmin Tan and colleagues, reporting in the Journal of Agricultural and Food Chemistry, tested magnolia bark's germ-killing ability in a Wrigley lab.

They found it highly effective against three types of oral microorganisms, killing 99.9 per cent of bad breath bacteria within five minutes.

Tests on nine healthy Wrigley employees who chewed mints and gum containing the bark after lunch produced less dramatic but still potent effects.

The mints killed off more than 61 per cent of the germs that cause bad breath within 30 minutes - comparable to some commercial mouthwashes. Mints without the extract were only 3.6 per cent effective.

The gum didn't work as well, reducing oral bacteria by 43 per cent within 40 minutes, compared with an 18 per cent reduction in gum with no extract.

The extract also helped kill a group of bacteria that causes tooth decay.

"Because bacteria are the major cause of breath odour, products containing effective germ-kill compounds will provide a long-lasting reduction of oral maloduor," the researchers wrote.

But don't expect it in stores any time soon.

"It's a long way from scientific research to a commercialisable product, and there's a lot of perils and pitfalls along the way," said Wrigley spokesman Chris Perille.