Scientists may have found a cure for sweet-tooth syndrome

If you have a sweet tooth that leads you astray, help may be at hand. Japanese researchers have discovered that a protein known to reduce food intake can also act as a sweet-tooth antidote, making chocolate and other goodies less tasty.

The work was done by researchers from the Tokyo Medical and Dental University, Asahi University School of Dentistry, Kyushu University and the Japanese Ministry of Agriculture, Forestry and Fisheries. Their results are published this week in the US Proceedings of the National Academy of Sciences.

The team was experimenting with leptin, a protein produced by fat cells. Leptin is known to curb food demand while increasing the body's energy usage through its action on a part of the brain called the hypothalamus.

Leptin acts by connecting to leptin receptors. The new work from Japan has identified these in the cells and nerves of the tongue.

The study was conducted using mice. When these were injected with leptin they showed significantly reduced taste responses to sweets, although there was no change in how they responded to salty, sour or bitter substances. The scientists were able to describe the biochemical means by which leptin suppressed the taste response to sweets.

In a second experiment the researchers used genetically engineered mice. These animals were chronically overweight because they lacked working leptin receptors. When extra leptin was administered to this group of mice they continued to munch through sweets as readily as if they had received none of the protein.

The discovery opens up the possibility that leptin may have a similar effect in humans, taking the enjoyment out of the "bad" foods we like by reducing their pleasurable taste on the tongue.