Britain facing cancer timebomb in the under-50s due to poor diet and gut health - and ultra-processed food could be to blame

Poor diet and gut health are leaving the UK facing a surge in cancer cases in the under-50s, research suggests.

More young people than ever are getting cancer, with diagnosis rates rising by a quarter in two decades.

Around 100 younger people a day – 35,000 a year – are being diagnosed with rising numbers of cancers commonly seen in older people, such a bowel, breast and stomach.

Scientists believe the 'disturbing' trend may have a link to people eating too much ultra-processed food. Rising cases of bowel cancer, for example, may have an association with changes to the gut microbiome reducing the body's ability to deal with pre-cancerous cells, according to research presented at the world's biggest cancer conference.

Professor Charles Swanton, Cancer Research UK's chief clinician, said cancer still predominantly affects older people but scientists are alarmed at its rising presence in younger people. 

At the American Society of Clinical Oncology's annual meeting he said: 'Over recent decades, there has been a clear increase in cancer incidence rates in young adults in the UK.' He added: 'We don't have a good answer as to why this is happening.'

The incidence rate of 'early onset' cases grew from 132.9 per 100,000 people in 1995 to 164.6 in 2019, analysis by Cancer Research UK of the most recent data shows. 

The overall incidence rate across all ages increased 13 per cent, from 539 per 100,000 people to 611.5 during this timeframe.

Research by Ohio State University presented at the Chicago meeting found under-50s with bowel cancer had cells that appeared to be 15 years older than their real age.

It suggests Western diets are impacting the balance of bacteria and inflammation in the gut, which can cause 'accelerated ageing' in the colon. 

Bacteria called fusobacterium, linked to diets low in fibre but high in sugar, was found to increase inflammation in the gut, in turn raising the risk of cancer.

The findings add to growing evidence that illness and disease can occur through changes to the microbiome as well as damage from long-term swelling.

He added: ‘In some instances, then there are maybe associations emerging that distinct microbial species may be associated with early onset cancer risk.

‘What we are seeing in some studies is some tumours from patients with early onset colorectal cancer harbour mutations that might be initiated by these microbial species.

‘Suggesting that potentially some of these microbes might initiate mutations in DNA. This is not dissimilar from the way that tobacco smoke induces mutations in in lung lining cells.’ The global phenomenon hit the headlines in March when the Duchess of Wales announced she had been diagnosed with an undisclosed form of cancer following earlier abdominal surgery, age just 42.

Other high profile examples include Dame Deborah James, the campaigner and podcast host who died of bowel cancer in 2022, aged 40, and Girls Aloud star Sarah Harding who died of breast cancer in 2021 at just 39.

Professor Swanton suggested scientists were still ‘some way from proving that those microbial species directly cause cancer’, adding that inflammation of the gut often linked to obesity was also a likely factor.

But the concern is so great, it has led Cancer Research UK to set up a ‘Grand Challenge’ research programme to examine this and other possible causes.

He added: ‘In some instances, then there are maybe associations emerging that distinct microbial species may be associated with early onset cancer risk.

‘What we are seeing in some studies is some tumours from patients with early onset colorectal cancer harbour mutations that might be initiated by these microbial species.

‘Suggesting that potentially some of these microbes might initiate mutations in DNA. This is not dissimilar from the way that tobacco smoke induces mutations in in lung lining cells.’ The global phenomenon hit the headlines in March when the Duchess of Wales announced she had been diagnosed with an undisclosed form of cancer following earlier abdominal surgery, age just 42.

Other high profile examples include Dame Deborah James, the campaigner and podcast host who died of bowel cancer in 2022, aged 40, and Girls Aloud star Sarah Harding who died of breast cancer in 2021 at just 39.

Dr Cathy Eng, a bowel cancer doctor at Vanderbilt University Medical Centre in Nashville, said the rise of the disease among under-50s was being seen globally and that otherwise healthy patients are increasingly presenting with advanced bowel cancer in their 20s, 30s and early 40s. 

She said: ‘They are not necessarily obese or unhealthy looking and you would have no idea they had cancer.

‘Research has correlated it with high blood pressure, high cholesterol, diabetes and sedentary lifestyles, as well as links to tobacco and alcohol.

‘It’s not necessarily what you eat, there is also interesting research regarding antibiotic use and what you have been taking into your body since childhood.’