There really is only one main cause of bad breath, and that's a buildup of bacteria in the mouth.  The source of those bacteria is then going to give you the real source of your bad breath.

For example, many digestive disorders can cause bad breath.  If you have acid reflux disease, when the stomach acids regurgitate back up into the esophagus, you may also have bad breath due to the bacteria also making its way to your throat and mouth. Liver problems also may cause bad breath as the liver is supposed to filter toxins out of the body.  So what scientific research says about bad breath and its cause can actually deal with your constant indigestion, constipation, and so on. 

Bacteria also builds up in the mouth as well, from food particles that have not been brushed away or from having a very dry mouth, which causes these particles to stick to the teeth, gums, and tongue.

Scientific Research About Bad Breath Cures
Once you understand these common causes of bad breath, then of course your next question deals with how to cure it.  Getting rid of these bacteria at the source is the real treatment for bad breath. This is what scientific research says about bad breath cures; just chewing gum or sucking on mints is not going to do anything for the long-term. 

Proper oral hygiene is the first step toward treating halitosis correctly. Be sure to brush and floss every day, especially after eating.  And if you have digestive problems consistently, talk to your doctor about this. Your stomach and intestinal problems may also be tied in with your halitosis, so you need to get those fixed.

Latest Oral Technology
Do you know that your bathroom is full of germs? Without proper storage, you could be sending some of these nasty germs into your mouth unknowingly. Check out the video below. 

The Germ Terminator is the only FDA 510(k) cleared medical device of its kind designed for household use that kills greater than 99.9999% of all germs tested. After killing the germs on toothbrushes the system stores toothbrushes in a germ-free environment. The Germ Terminator gives you peace of mind knowing that you are protecting your health, and the health of your loved ones, every time you brush.

Here's one testimonial from one of their satisfied customers.
I never knew that my toothbrush had over 100 million germs on it. I'm not necessarily a germ freak, but when you read the articles and you hear about everything that is left on your toothbrush and them you're putting that toothbrush back in your mouth... People don't sanitize their toothbrushes because they don't know. After trying the Germ Terminator, people would say the same thing that I do, "Its easy, its convenient, why not use it after you know the research?" I think people should definitely sanitize their toothbrushes because of all the germs that just keep building and building up on your toothbrush. Using the Germ Terminator just makes sense.
Joe - Office Manager

You can check out the Germ Terminator here.