Certain foods, health conditions and even habits can contribute to the existence of halitosis (bad breath).

Food:

Food starts the process of breaking down in our mouth when the teeth start to break chunks of food that have been bitten into smaller pieces by biting, tearing and chewing. Food particles can be trapped in between teeth, which can cause foul odor. Food also can contain oils that can be another source of bad breath. Certain foods like onions and garlic are good examples of foods that cause bad breath. Others are vegetables and spices. The oils in foods are first digested and the pungent oils are absorbed into the bloodstream. Then they are carried to your lungs where they are given off in your breath when you exhale, until the food is eliminated from your body.

Alcohol behaves in your body, much the same way as food. This is how breath analyzer tests work. What people smell on the breath of someone who has been drinking is not the alcohol but the components that are contained in the drink other than the alcohol.

Dental Problems:

Poor hygiene can lead to periodontal disease, which can lead to bad breath. If you forget to brush or floss, bacteria will collect in your mouth and on your tongue, which will emit hydrogen sulfur gases.

Another problem of poor oral care is that when you don't brush and floss properly gingivitis and tooth decay can result. Plaque-filled pockets form between your teeth and gums (periodontitis), can cause bad breath.

If you wear dentures and fail to clean them properly or if they do not fit properly and leave gaps where odor-causing bacteria and food particles and gather, you will experience bad breath.

Dry Mouth:

Saliva is used to moisten your mouth and cleanse it. When you do not have enough saliva due to dehydration, dead cells can accumulate on your tongue, gums and the inside of your mouth cheeks. These cells begin to decompose and then can cause odor.

Dry mouth is something that normally occurs while you sleep due to the many hours where you do not consume any water. We wake with "morning breath". Those individuals who sleep with their mouth open suffer from dry mouth more than those who keep their mouth closed during sleep. Certain medications can lead to dry mouth as a side effect of the medication. There can also be medical problems with the salivary glands preventing them from producing saliva.

Diseases:

Bad breath can also be caused by chronic lung infections and lung abscesses. Very distinctive breath odor can be signal for certain illnesses. Kidney failure can cause a urine-like odor to your breath, liver failure may cause an odor that smells like fish, and those who have uncontrolled diabetes can have a fruity breath. Individuals who have chronic reflux of stomach acids (GERD) or have a small protrusion of the stomach into the chest cavity (hiatal hernia) can also have bad breath.

Mouth, Nose, Throat Conditions:

Those who suffer from sinus infections and have nasal discharge from their sinuses that drip down the back of the throat can have a bad odor to their breath. Kids who have foreign object stuffed into their noses can have bad breath. Strep throat, tonsillitis and mononucleosis can also cause bad breath. Those who cough up sputum like those with bronchitis and other upper respiratory infections can have bad breath. Canker sores of the mouth can also cause bad breath, especially if periodontal disease also exists.

Tobacco:

Tobacco products cause a very unpleasant stink from the mouth and are also more likely to have periodontal disease, which will also give them bad breath.

Fasting:

Those who diet frequently may also have a "fruity breath" from ketoacidosis, which is the breaking down of chemicals while fasting.