Craving sweets has a genetic basis, scientists have revealed.

A team led by Robert Margolskee of the Mount Sinai School of Medicine at New York University has found a gene that enables the tongue's taste receptors to identify sweet things.

The discovery could lead to the development of new sweeteners and a greater understanding of why some people have a sweet tooth.

Progress has been made in identifying receptors for other tastes, such as sour, bitter and salty. But until now the taste for sweet things has remained elusive.

Chemical clue

Being able to identify sweet things probably played a crucial role in our evolution. It enabled our ancestors to distinguish between bitter food sources, such as deadly plants, and sugary food, which is rich in energy.

There is now considerable commercial interest in developing new sweeteners, and scientists have been searching for the mechanisms underlying sweet taste.

Two teams of researchers in the United States may have succeeded. They think they have tracked down a gene which functions as a sweet taste receptor.

The work was based on studies of two strains of lab mice. One strain liked drinking water laced with sugar or saccharin while the other preferred plain water.

Genetic database

After locating a gene in mice that seems to give the rodents a sweet tooth, the scientists then searched a database for similar genetic sequences in humans.

It appears that a tiny change to a gene determines whether mice, and possibly people, have a preference for sweet things.

"It seems fitting that the presence or absence of a sugar chain on a sweet taste receptor should determine sensitivity and preference for sweetness in life," Robert Margolskee and colleagues write in the journal Nature Genetics.

"Such information would be particularly useful for the identification of novel sweeteners of intense potency," they add.

A similar study, carried out by a team at Harvard Medical School, Boston, US, is reported in the journal Nature Neuroscience.