An estimated 65 percent of Americans suffer from halitosis, or bad breath, according to the Washtenaw District Dental Society. But where does it come from? According to a TED-Ed video narrated by professor and bad breath researcher Mel Rosenberg, all comes down to the activity of bacteria in the mouth. "Bacteria in your mouth feed off of mucus, food remnants and dead tissue cells. In order to absorb nutrients through their cell membranes they must break down the organic matter into much smaller molecules," Rosenberg said.