Drinking two or more sugary drinks a day more than doubles younger women’s risk of bowel cancer, researchers have warned.
A new study found that each daily serving was linked with a 16 per cent higher risk of the disease.
But it found that replacing sugar-sweetened beverages with artificially sweetened drinks, coffee or milk led to a lower risk of disease.
Cases of bowel cancer diagnosed before the age of 50, formally known as early onset colorectal cancer, have been increasing in many high income countries over the past two decades.
In the US, adults born around 1990 run twice the risk of colon cancer and four times the risk of rectal cancer compared to those born around 1950.
Scientists are not sure why, but suspect there could be a link to increased consumption of sugary drinks.
However, it is known that sugar-sweetened drinks suppress feelings of satiety, so risk excess energy intake and associated weight gain.
These drinks also prompt a rapid rise in blood glucose and insulin secretion, which, over the long term, can induce insulin resistance, inflammation, obesity and type 2 diabetes.
Emerging evidence also suggests that fructose can impair gut barrier function and increase gut permeability, which could promote the development of cancer.
A team of researchers in the US examined data on sugar-sweetened beverages among more than 95,000 women who had reported their consumption levels every four years.
And around 41,000 of these women also had data of their sugary drink consumption in adolescence based on previous surveys.
The team found that during the follow-up period, there were 109 cases of early-onset bowel cancer found among the study participants – meaning they were diagnosed under the age of 50.
The study, published in the journal Gut, concluded that compared with people who drank less than one sugar-sweetened beverage each week, women who drank more than two of these sugary drinks each day had a 2.2-fold higher risk of early bowel cancer.
Replacing each serving per day of a sugar-sweetened beverage with an artificially sweetened drink, coffee, reduced fat milk or whole milk, was linked to a 17 to 36 per cent lower risk of bowel cancer, they added.
"Sugar-sweetened beverage consumption may contribute to the rising incidence of early onset colorectal cancer," the team wrote.
"Reducing sugar-sweetened beverage intake and/or replacing sugar-sweetened beverages with other healthier beverages among adolescents and young adults may serve as a potential actionable strategy to alleviate the growing burden of early onset colorectal cancer."
Dr Lisa Wilde, director of research and external affairs at Bowel Cancer UK, said: “This study further shines a light on the complicated relationship between our diet, lifestyle and risk of developing bowel cancer. Although the disease is much more common in the over 50s, each year more than 2,500 people under the age of 50 will be diagnosed with bowel cancer in the UK. The disease is the fourth most common cancer in the UK, every 15 minutes someone is diagnosed, but we know that around half of all bowel cancers could be prevented by having a healthier lifestyle.
“Making simple changes to your diet like limiting sugary drinks, having plenty of wholegrains and fibre, avoiding processed meat and limiting red meat, being of a healthy body weight, having regular physical activity, stopping smoking and cutting down on alcohol can help stack the odds against developing bowel cancer.”
Last December ministers announced that free refills of sugary drinks would be banned, as part of a plan to tackle obesity.
This came alongside a promise to ban “buy one get one free” offers on unhealthy foods.
The restrictions, which cover any multi-buy promotion, will apply to foods high in fat, salt or sugar – including cakes, crisps, soft drinks, breakfast cereals, pizzas and ready meals. Small stores are exempt from the plans.
The measures will come into force from April 2022.