What you eat affects the air you exhale. Certain foods, such as garlic and onions, contribute to objectionable breath odor. Once the food is absorbed into the bloodstream, it is transferred to the lungs, where it is expelled. Brushing, flossing and mouthwash will only mask the odor temporarily. Odors continue until the body eliminates the food. Dieters may develop unpleasant breath from infrequent eating.

If you don't brush and floss daily, particles of food remain in the mouth, collecting bacteria, which can cause bad breath. Food that collects between the teeth, on the tongue and around the gums can rot, leaving an unpleasant odor. Dentures that are not cleaned properly can also harbor odor-causing bacteria and food particles.

One of the warning signs of periodontal (gum) disease is persistent bad breath or a bad taste in the mouth. Periodontal disease is caused by plaque, the sticky, colorless film of bacteria that constantly forms on teeth. The bacteria create toxins that irritate the gums. In the advanced stage of the disease, the gums, bone and other structures that support the teeth become damaged. With regular dental checkups, your dentist can detect and treat periodontal disease early.

Bad breath is also caused by dry mouth (xerostomia), which occurs when the flow of saliva decreases. Saliva is necessary to cleanse the mouth and remove particles that may cause odor. Dry mouth may be caused by various medications, salivary gland problems or continuously breathing through the mouth. If you suffer from dry mouth, your dentist may prescribe an artificial saliva, or suggest using sugarless candy and increasing your fluid intake.

Tobacco products cause bad breath, stain teeth, reduce one's ability to taste foods and irritate gum tissues. Tobacco users are more likely to suffer from periodontal disease and are at greater risk for developing oral cancer. If you use tobacco, ask your dentist for tips on kicking the habit.

Bad breath may be the sign of a medical disorder, such as a local infection in the respiratory tract (nose throat, windpipe, lungs), chronic sinusitis, postnasal drip, chronic bronchitis, diabetes, gastrointestinal disturbance, liver or kidney ailment. If your dentist determines that your mouth is healthy, you may be referred to your family doctor or a specialist to determine the cause of bad breath.

Eliminating periodontal disease and maintaining good oral health is essential to reducing bad breath. Schedule regular dental visits for a professional cleaning and checkup. If you think you have constant bad breath, keep a log of the foods you eat and make a list of medications you take. Some medications may play a role in creating mouth odors. Let your dentist know if you've had any surgery or illness since your last appointment.

Brush twice a day with a fluoride toothpaste to remove food debris and plaque. Brush your tongue, too. Once a day, use floss or an interdental cleaner to clean between teeth. If you wear removable dentures, take them out at night. Clean them thoroughly before replacing them the next morning.

Mouthwashes are generally cosmetic and do not have a long-lasting effect on bad breath. If you must constantly use a breath freshener to hide unpleasant mouth odor, see your dentist. If you need extra help in controlling plaque, your dentist may recommend using a special antimicrobial mouthrinse. A fluoride mouthrinse, used along with brushing and flossing, can help prevent tooth decay.

Look for products that carry the American Dental Association Seal of Acceptance. Products that display the seal have undergone strict testing for safety and effectiveness.