Food. The breakdown of food particles in and around your teeth can cause a foul odor. Eating foods containing volatile oils is another source of bad breath. Onions and garlic are the best known examples, but other vegetables and spices also can cause bad breath. After these foods are digested and the pungent oils are absorbed into your *lo**stream, they're carried to your lungs and are given off in your breath until the food is eliminated from your body.

Alcohol behaves in the same fashion, allowing the measurement of alcohol levels by breath tests. Alcohol itself has almost no odor, however. The characteristic smell on your breath is mainly the odor of other components of the beverage.

Dental problems. Poor dental hygiene and periodontal disease can be a source of bad breath. If you don't brush and floss daily, food particles remain in your mouth, collecting bacteria and emitting hydrogen sulfur vapors. A colorless, sticky film of bacteria (plaque) forms on your teeth.

If not brushed away, plaque can irritate your gums (gingivitis) and cause tooth decay. Eventually, plaque-filled pockets can form between your teeth and gums (periodontitis), worsening this problem and your breath. Dentures that aren't cleaned regularly or don't fit properly also can harbor odor-causing bacteria and food particles.