The tongue has built-in taste for fatty food. In experiments with rodents, French scientists identified a receptor on the tongue that appears to detect dietary fat. This counters the traditional view that the taste buds pick up only five basic flavors: sweet, sour, salty, bitter and "umami," — a flavor associated with the food additive monosodium glutamate (MSG).

The fact that the tongue harbors receptors for fatty acids could shed new light on appetite control and obesity, according to the researchers, led by Philippe Besnard of the University of Bourgogne.

Scientists have speculated that the tongue may have a receptor designed to detect fat, but this study is the first to pinpoint one, according to Besnard and his colleagues. The receptor, a protein called CD36, is already known to exist in many tissues and is involved in fat storage, among other jobs; it is also goes by the name of fatty acid transporter, or FAT.

Rats and mice, not to mention many humans, have a natural preference for fatty food, and rats have already been shown to have CD36 proteins in their taste buds.

To see whether CD36 might be the tongue's fat detector, Besnard and his colleagues studied rats and mice that were either normal or had the gene for CD36 "knocked out," inactivating the protein.