Bad breath is caused by anaerobic sulfur producing bacteria that live in the back of your tongue, throat, and tonsils. Now, bad breath can also be caused by foods. And those foods already contain sulfur compounds, or those foods can stimulate the bacteria to produce sulfur compounds. The mechanism by which these bacteria create odors is by breaking down proteins. The amino acids in those proteins can contain sulfur compounds, and as they chop them up they produce chemicals.
One is called cadaverine. Another is called putrescine, not my sister in law’s name. Those are real chemicals. It’s the smell of rotting flesh. One condition that exacerbates the whole problem is dry mouth. And that’s because saliva is nature’s way of keeping your breath fresh. Saliva has oxygen in it. Oxygen’s a natural enemy of these bacteria. Once your mouth is dry, you can’t fight the bacteria, and you end up with bad breath throughout the day, or a condition called halitosis.
Now, many medications can cause the problem because many medications have dry mouth as a side effect. Many oral products can make the condition worse because they contain alcohol or a drying agent in toothpaste called sodium lauryl sulfate. And it could be a physical condition. Sometimes people have large tonsils, or they trap the bacteria and they get a condition called tonsil stones, where they get little globs growing inside the tonsils. They may have excess mucous. Mucus has proteins in it, which act as a fuel for the bacteria. So the wide combination of all these — a lot of this information can be found in my book called The Bad Breath Bible, which you can download from therabreath.com