Twenty percent of the general population (and 90 percent of the people around your office water cooler) have bad breath. Known formally as halitosis, it is also the number three reason why people visit their dentist, following tooth decay and gum disease. Where does it come from, and what can yo do about it? Here are some tips.

Watch what you drink. Alcohol and caffeine can actually dry out your mouth, which encourages the bacteria that cause halitosis. A dry mouth from not making as much saliva while you sleep also explains "morning breath."

Brush your tongue. Bacteria on the tongue is the leading cause of bad breath. Clean yours with your toothbrush or a tongue scraper. Scrapers will do a slightly better job.

A low-carbohydrate/high protein diet will cause your body to start burning fat for energy. That process makes compounds called ketones, which cause bad breath. No amount of tooth or tongue brushing will fix this. Your best bet is to mask your breath with breath mints orsugar-free gum.

Respiratory tract infections like colds and bronchitis can also give you bad breath. That's because odor-causing bacteria like to feed on mucus. If you have a stuffy nose, you are more likely to resort to mouth-breathing, which can dry out your mouth.

Are you suffering from an ulcer? The same type of bacteria that causes ulcers can also trigger bad breath. Have your doctor test you for H. pylori and prescribe antibiotics for it.

Spicy food may cause halitosis by itself, or it may cause acid reflux, and your bad breath may be from some undigested food coming back up. Alternately, the irritation from stomach acid is giving you postnasal drip. Treat the acid reflux and you will be treating the halitosis.

Dried fruits are very high in sugar, and odor-causing bacteria love to feed it. Dried fruit is also very sticky, so it can get trapped on and between your teeth. After a snack, be sure to floss and brush.

More than 400 prescription and over-the-counter drugs can impair saliva flow. Saliva helps wash away food and bacteria, keeping bad breath in check. Since you usually are not at liberty to change your meds, try to keep your mouth hydrated by chewing sugarless gum, or using an oral rinse regularly.

Tonsil stones are small clusters of hardened bacteria, food particles, dead cells, and mucus that get trapped in the ridges of your tonsils and the back of your tongue. These will often dislodge on their own, but you can sometimes speed the process by gargling with salt water.

Cracked teeth and fillings can trap food particles and breed bacteria, resulting in cavities, gum disease, and bad breath. Ill-fitting dentures can cause the same problems.