Mice use halitosis like a menu, scientists discover

While bad breath can put humans off their lunch, for mice it is a key part of finding food that is safe to consume. Researchers from the U.S., Germany and Russia have found that mice often determine what to eat based on the halitosis and sulfuric chemicals on the breath of their peers.

Previous studies had determined that the rodents used their noses to choose food sources when around other mice. However, how they did it was a mystery.

In a study recently published in the journal Current Biology, physiologists and neurobiologists said they had the answer. A subset of the olfactory, or smell, system in mice, called the GC-D necklace subsystem, detects chemicals on mouse breath that indicate a safe meal.

The chemical is carbon disulfide, a compound already associated with social learning in mice. In humans, most bad breath odors are composed of similar sulfur-based molecules like hydrogen sulfide and dimethyl sulfide, which smell like rotten eggs and cabbage, respectively.

After testing the rodents' response to the molecule, the team concluded that mice who do not detect carbon disulfide on their peers' breath will not modify their eating preference, while those that do, will.

The researchers added that humans typically react to visual cues, like someone wincing after taking a bite of food. Halitosis has no known positive effect on human eating. Preventing bad breath can be as simple as brushing the teeth regularly and rinsing with a specialty breath freshener.