Scientists have long known that drinking alcohol can increase your risk of developing cancer.

But what they didn’t understand until now, was that this is because drinking actually damages the DNA blueprint in your stem cells.

Not only that, but the new research also discovered that some groups of people are more vulnerable to this cellular-level damage than other people.

“Alcohol contributes to over 12,000 cancer cases in the UK each year,” says Professor Linda Bauld, Cancer Research UK’s expert on cancer prevention.

These include seven types, the most common of which are breast and bowel.

In all previous studies of the link between alcohol and cancer, research has been done on cell cultures.

But the most recent study was different because it used live mice to show how alcohol exposure leads to permanent genetic damage.

The mice were given ethanol and their chromosomes analysed before and after.

This analysis revealed acetaldehyde, a harmful chemical produced when the body processes alcohol, changed the mouse DNA sequencing.

In fact, acetaldehyde was able to break and damages their DNA leading to permanent rearrangement of chromosomes.

This is important because such faulty cells give rise to cancer.

Professor Ketan Patel, lead author of the study, said: “While some damage occurs by chance, our findings suggest that drinking alcohol can increase the risk of this damage.”

They then went on to look at how the body tries to protect itself against this assault by alcohol and found that there are two lines of defence.

 The first is a family of enzymes called aldehyde dehydrogenases (ALDH) which break down harmful acetaldehyde into acetate, which our cells can use as a source of energy.

But worldwide millions of people (particularly those from South East Asia) lack, or have faulty versions of, these enzymes meaning when they drink acetaldehyde builds up.

Short term this can result in a flushed complexion or feeling unwell but long term they found it resulted in four times as much DNA damage in their cells compared to mice with the fully functioning ALDH2 enzyme.

Professor Patel added: “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. 

“But it’s important to remember that alcohol clearance and DNA repair systems are not perfect and alcohol can still cause cancer in different ways, even in people whose defence mechanisms are intact.”