Sugar. Consuming sugar can also cause bad breath. Chewing gum or eating candy or mints that are not sugar-free can actually increase halitosis. The sugar acts as fuel for some bacteria to produce compounds that release offensive odors. Other bacteria in the mouth use sugar in the production of glycan strands. Glycan strands cause plaque to form on your gums and teeth. The plaque not only looks filmy but is also another cause of bad breath. Sugar, and other carbohydrates, that are improperly digested, can cause gas and bloating, which also can result in foul smelling breath.