LONDON, Jan. 5 (Xinhua) -- Drinking alcohol may cause irreversible damage to the DNA of stem cells and increase the risk of developing certain cancers, a new study has revealed.

Using genetically modified mice, British scientists found that acetaldehyde, a toxin produced as the body processes alcohol, can slice through the DNA within blood stem cells and cause permanent damage.

In the study, published recently in the journal Nature, the mice lost their ability to reproduce fresh blood after being given diluted alcohol for ten days.

Sequencing the genome of the stem cells indicated that their DNA had been scrambled to the point that the cells no longer functioned.

When healthy stem cells are faulty, they can give rise to cancerous cells, particularly in the mouth, throat, oesophagus, breast and so on.

The effects of such damage can be neutralized, however, by the body's two-layer defence mechanism. The first layer is a protective enzyme called aldehyde dehydrogenase 2 (ALDH2), which prevents build-ups of acetaldehyde, and the second repairs the DNA damage.

In the study, mice lacking ALDH2 suffered four times as damage compared with the other ones.

About 8 percent of the world's population, mostly those of East Asian ancestry, are born with an deficiency in ALDH2.

"Our study highlights that not being able to process alcohol effectively can lead to an even higher risk of alcohol-related DNA damage and therefore certain cancers," said Ketan Patel, who led the research at the MRC Laboratory of Molecular Biology in Cambridge.