Saliva is one of our body's strongest soldiers battling bacteria. Foods that promote saliva production, such as tart or sour foods including lemons, limes, cherries and cranberries, can help your body fight bacteria in your mouth. Drinking water is another great way to produce saliva, clear bacteria and cleanse your oral cavity. Foods that have a high water content also help to thwart the process of decay by diluting the sugars in the foods you consume. In other words, eat your fruits and veggies.