Ultra processed foods may raise early bowel cancer risk

Ultra-processed foods linked to higher risk of early bowel polyps in younger women

Ultra-processed foods (UPFs) have been linked to a substantially increased risk of abnormal bowel growths associated with early-onset colorectal cancer, according to a major new global study published in JAMA Oncology.

A landmark analysis of more than 29,100 women found that those who consumed the highest amounts of UPFs had a 45 per cent higher risk of developing precancerous bowel polyps before age 50.

New evidence highlights rising early-onset colorectal cancer

Researchers note that colorectal cancer is the only major cancer type increasing significantly in people under 50, prompting scientists to examine potential environmental and dietary factors.

UPFs—often low in fibre and high in additives, emulsifiers, and artificial sweeteners—have long been suspected of harming gut health, but their role in early abnormalities has been understudied until now.

The study was conducted by PROSPECT, funded by Cancer Grand Challenges, a global initiative supported by Cancer Research UK and the US National Cancer Institute.

What the new study found

Researchers analysed lower-endoscopy results of women aged 25–42 enrolled in the long-running Nurses' Health Study II, excluding anyone with prior colorectal disease or cancer.

Key findings

• Women who consumed the most UPFs had a 45% higher risk of early-onset tumours.
• Artificially sweetened drinks were a major contributor to this trend.
• UPFs accounted for 35% of daily calorie intake, averaging 5.7 servings per day.
• High UPF consumers also had higher BMI, more smoking history, and a greater prevalence of type 2 diabetes.

The researchers warned that combinations of additives may have a “cocktail effect”—disturbing the gut barrier, altering the microbiome, and potentially speeding early carcinogenic processes.

Experts call for stronger public health measures

Dr Andrew Chan of Massachusetts General Hospital said rising early-onset colorectal cancer remains poorly understood, but diet, lifestyle patterns, and microbiome disruption appear to play key roles.

Professor Charles Swanton, Chief Clinician at Cancer Research UK, noted that while the study does not prove causation, it provides crucial insight into how diet may influence early bowel changes.

Cancer Research UK estimates that 54% of bowel cancer cases are preventable, urging broader policy changes to make nutritious diets more accessible.

Why this matters

Bowel cancer remains one of the most common cancers globally, with:

• 44,000 cases annually in the UK, and
• 142,000 cases yearly in the US.

Rates among 25–49-year-olds have risen over 50% since the 1990s, and the cancer is projected to become the most common cancer in Americans under 50 by 2030.

Early symptoms may include:

• persistent changes in bowel habits
• unexplained diarrhoea or constipation
• blood in the stool
• abdominal pain or bloating
• unexplained weight loss and fatigue

Medical experts urge anyone experiencing these symptoms to seek clinical advice promptly.

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