Though the notion has been around for a while, the idea that green tea fights bad breath has recently made a bit of a comeback. Does it work? After all, most green teas aren't marketed as freshening your breath, though plenty of other positive health effects are ascribed to them. So what's the deal? Does green tea reduce bad breath?
As with most products that are not specifically formulated to combat halitosis, the answer is basically "Yes, if..." or "No, but..."
Unsweetened green tea is a very healthy beverage, to be sure. It contains polyphenols, which are a class of compounds that have antioxidant and anti-inflammatory effects. By drinking green tea as part of a complete diet, you may be reducing the amount of damage in your body caused by free radicals, as well as improving your heart health.
However, that doesn't mean your breath automatically gets better with a few sips of the drink. While green tea's compounds may inhibit the activity of bacteria on your tongue, it does not necessarily give your mouth a sweet smell.
Consider the textbook Chemistry and Applications of Green Tea, which collects a wealth of research on the subject. It's eleventh chapter, by Hibino and Sakanaka, deals with the ability of green tea's polyphenols to neutralize odors.
The authors found that the beverage does a fairly good job of ridding the mouth of volatile sulfur compounds (VSCs), which are what you smell when your nose detects a hint of halitosis.
The chapter noted that green tea polyphenols deodorize the smells of trimethylamine, which gives fish its foul smell, and the VSC methyl mercaptan, as well as reduce the odors of ammonia and tobacco smoke in the mouth.
The authors suggest that green tea extract may be added to candy as a way to beat bad breath when the beverage is not available.
There is some truth to these findings. A study in the Journal of Dental Research determined that catechins, the most common type of polyphenol in green tea, inhibits the expression of the MGL gene, a stretch of DNA that is responsible for VSC production in many bacteria.
However, even if you could saturate your teeth and tongue in green tea night and day, your mouth would still be ripe for bacterial growth and tooth decay. Specialty breath freshening products neutralize odors more completely, and oral care probiotics replace the bacteria on your tongue, two things green tea cannot do.