WIKIMEDIA, TIIA MONTOA metabolite of alcohol known as acetaldehyde, which occurs naturally at low levels, causes double-stranded breaks in the DNA of mouse blood stem cells, according to a study published today (January 3) in Nature. Unrepaired breaks can lead to large deletions and chromosome rearrangements, and the mutations are passed on to daughter cells that make up the blood.

“How exactly alcohol causes damage to us is controversial,” study coauthor Ketan Patel of the Medical Research Council Laboratory of Molecular Biology tells The Guardian. “This paper provides very strong evidence that an alcohol metabolite causes DNA damage [including] to the all-important stem cells that go on to make tissues.”

Normally, the enzyme aldehyde dehydrogenase 2 (ALDH2) quickly oxidizes acetaldehyde into acetate, which cells use as a source of energy. But many people, including millions in Southeast Asia, carry mutations in the ALDH2 gene that causes the accumulation of acetaldehyde. These people, who are known to have an increased risk of developing esophageal cancer, may also be more susceptible to blood cancers, if the new results hold true in humans: ALDH2­ knockout mice suffered four times as much DNA damage as their wildtype counterparts after alcohol consumption, according to the study.

“This thought-provoking research highlights the damage alcohol can do to our cells, costing some people more than just a hangover,” Linda Bauld of Cancer Research UK says in a press release.