Scientists suspect that some bacteria, particularly bacteria located on the top of your tongue closest to your throat, actually protect against foul-smelling breath. Other types of bacteria, however, produce a pungent odor as they multiply. What does this research mean for you? The type of bacteria most prevalent on your tongue could mean the difference between good and bad breath. Unfortunately, researchers don't yet know how to tip the bacterial balance so that you'll always have naturally sweet-smelling breath [source: Gately].
There is one simple thing you can do to help, though: Clean your tongue. The rough surface of the tongue is home to a potentially foul-smelling combination of dead cells, food debris, bacteria and the byproducts of bacterial digestion -- factors that all contribute to less-than-fresh breath. Be sure to brush your tongue with your toothbrush after you brush your teeth. Or, for a more effective scrubbing, use a tongue cleaner. This handheld device is designed to scrape the surface of the tongue and remove odor-causing debris from its surface [source: Bosy].