Tongues have a taste for fatty food

Nov 2 2005

According to a new study French scientists say our tongues have an ability to detect fat in the diet which may explain our love of cheesecake, french fries and butter cookies.

In their experiments with rodents, French scientists identified a receptor on the tongue that appears to detect dietary fat.

This goes against 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).

According to the researchers, led by Philippe Besnard of the University of Bourgogne, the fact that the tongue harbours receptors for fatty acids could have some impact on appetite control and obesity.

In the past scientists have suggested 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 one of it's roles is involved in fat storage.

It is also called a fatty acid transporter, or FAT.

Rats and mice, along with many humans, have a natural preference for fatty food, and rats have already been shown to have CD36 proteins in their taste buds.

In order 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.

They found that while the genetically normal animals naturally opted for fattier fare when given the choice, the CD36-deficient mice had no such preference.

When the researchers put fatty acids on the tongues of the normal animals, this alone triggered a release of fat-processing substances from the digestive organs.

The same was not true of mice lacking CD36 activity.

Besnard says that though the body's regulation of fat intake is complex, these findings point to the importance of CD36 receptors on the tongue.

The report is published in the November issue of the Journal of Clinical Investigation.