From Live Science:
An extract from coffee can inhibit the bacteria that lead to bad breath, scientists have discovered.Continue to read the whole article if you really care.
The extract prevents malodorous bacteria from making their presence felt — or smelt.
"Everybody thinks that coffee causes bad breath," said Tel Aviv University breath specialist Mel Rosenberg, "and it's often true, because coffee, which has a dehydrating effect in the mouth, becomes potent when mixed with milk, and can ferment into smelly substances."
But not always. Rosenberg and colleagues monitored the bacterial odor production of coffee in saliva.
"Contrary to our expectations, we found some components in coffee that actually inhibit bad breath," Rosenberg said...