Cooking oils and ultra-processed food may be fuelling the global surge in early-onset bowel cancer, a study suggests.

Experts who analysed 162 tumour samples from patients warned that our diets may be hindering the body’s natural healing processes.

Overconsumption of seed oils - including sunflower, rapeseed, sesame and peanut oil - used in packaged products may be causing chronic inflammation.

And a shift in Western diets towards eating more ultra-processed foods, sugars and saturated fats is also feared to have increased cancer risk.

Dr Timothy Yeatman, professor of surgery at the University of South Florida, said: “A human’s immune system can be extremely powerful and drastically impact the tumor microenvironment, which is great if harnessed correctly for health and wellness.

“But not if it’s suppressed by inflammatory lipids from processed foods.”

Dr Yeatman and his team at USF Health and Tampa General Hospital Cancer Institute found that samples of colorectal cancer contained a high number of molecules that promote inflammation, and lacked those that can reduce it and promote healing.

This could be causing an imbalance of the immune system and driving chronic inflammation, the researchers said.

Dr Yeatman added: “It is well known that patients with unhealthy diets have increased inflammation in their bodies.

“We now see this inflammation in the colon tumors themselves, and cancer is like a chronic wound that won’t heal – if your body is living off of daily ultra-processed foods, its ability to heal that wound decreases due to the inflammation and suppression of the immune system that ultimately allows the cancer to grow.”

Consuming more healthy, unprocessed foods rich in omega-3 fatty acids could help to reverse the effects, the team suggested.

“This has the potential to revolutionise cancer treatment, moving beyond drugs to harness natural healing processes,” Dr Yeatman said.

“It’s a vital step toward addressing chronic inflammation and preventing diseases before they start.”

The findings were published in the journal Gut.