Scientists pinpoint exact number of alcoholic drinks a week that can raise risk of bowel cancer

WE all love studies that say the odd glass of red is good for our hearts, or that tequila might help the gut.

But time and again, new research emerges suggesting alcohol really is bad for us – just as we originally thought.

Experts from Cancer Research UK (CRUK) and the US National Cancer Institute (NCI) now all agree that alcohol contributes to at least seven different types of cancer, including bowel.

Adding to the damning evidence, scientists from the NCI now say they’ve identified the exact number of drinks that could raise your risk of the disease.

For the study, published in Cancer, a peer-reviewed journal of the American Cancer Society, the experts tracked 88,092 people for over 20 years.

During that time, 1,679 cases of bowel cancer were recorded.

The researchers found that people who drank an average of 14 or more drinks a week over their lifetime had a 25 per cent higher risk of developing bowel cancer, when compared with those who averaged fewer than one drink a week.

The same group also had a 95 per cent higher risk of rectal cancer.

The findings come amid a broader reckoning in the medical community over how to explain a sharp rise in colon cancer cases in people under 50. 

Between 1993 and 2018, the number of adults aged 25 to 49 diagnosed with the disease increased by 22 per cent.

In better news, researchers found the risk fell sharply among people who stopped drinking, even if they quit later in adulthood.

In fact, no increased cancer risk was seen in former drinkers.

They were also less likely to develop non-cancerous bowel growths, known as adenomas – which can go on to become cancerous – than people who currently drink fewer than one drink a week.

While the data were limited, the findings suggest quitting alcohol at any stage of adulthood may reduce risk.

“Our study is one of the first to explore how drinking alcohol over the life course relates to both colorectal adenoma and colorectal cancer risk,” said co-senior author Dr Erikka Loftfield of the NCI.

“While data on former drinkers were limited, it was encouraging to see that their risk may return to that of light drinkers.”

Experts believe that when the liver breaks down ethanol in alcohol, it produces the toxic chemical acetaldehyde, which can trigger inflammation in the colon.

This inflammation can damage DNA and lead to uncontrolled cell growth.

Alcohol also interferes with the body’s ability to absorb folate, a nutrient essential for DNA repair.

Low folate levels have consistently been linked to higher rates of colon cancer.

Alcohol is also dehydrating, which can slow digestion and contribute to constipation.

When stool moves more slowly through the digestive tract, harmful bacteria and toxins may remain in contact with the colon lining for longer, increasing the risk of DNA damage.