Your mouth contains millions of bacteria. In fact, there are probably more bacteria colonized in your mouth than there are cells in your entire body. Of the some 700 kinds of bacteria that thrive in the mouth, scientists have identified and studied fewer than half -- which makes it difficult to know exactly how to combat the odors that all those bacteria give off as a byproduct when they digest their food.
Regardless, there are a few things you can do to beat the bad breath caused by germs. Start by keeping your mouth clean: Your food supply is their food supply. Although you can try to kill bacteria with mouthwash, this is only a temporary solution. The bacteria will grow back over time. Your best defense is to brush your teeth thoroughly at least twice a day, and floss once a day. This will help remove the food trapped between your teeth, as well as the food trapped in the gum line. Otherwise, both of these areas would provide breeding grounds for bacteria. If food particles are left to linger, bad breath is imminent [source: Gately].