Colon cancer in young people: First-of-its-kind study links ultra-processed food to the rise

It’s not the elders’ disease anymore.When you think of colorectal cancer — more commonly known as colon cancer — you likely imagine someone over 50. However, the picture has changed in recent years, and increasingly, younger people are being diagnosed with what’s called early-onset colorectal cancer (EO-CRC).Colon cancer is a type of cancer that develops in the tissues of the colon or rectum. It starts in the large intestine (colon) and often develops from small, noncancerous clumps of cells called polyps. It's one of the most common types of cancer worldwide and the second leading cause of cancer death in the United States.

But why are young adults, especially those in their 20s, 30s, and 40s, falling prey to this deadly disease?A new study — first-of-its-kind — seems to have an explanation.

The new evidence highlights a possible key driver behind the surge of colon cancer in young people: the growing consumption of ultra-processed foods (UPFs) — those ready-to-eat or packaged items high in sugar, salt, fat, and additives.According to this large US study, women under 50 who consumed high amounts of UPFs had a significantly greater risk of early-onset bowel cancer precursor growths.Read on to know more.

Colorectal cancer among the young: what’s happening?

In recent years, the incidence of Colorectal cancer (CRC) among younger adults has risen sharply. Historically, a disease of older age groups, CRC is now being diagnosed increasingly in individuals under 50. According to the American Cancer Society, as many as one in five new CRC cases are now in people under age 55. A 2025 analysis published in The Lancet Oncology across multiple countries even confirmed the trend.The growth in early‐onset CRC is evident in multiple regions.

For instance, the report noted that in those aged 20-29, incidence rose by about 7.9 % a year in the period from 2004-2016 in Europe; the 30-39 group saw almost 4.9 % annual growth in that period. In the US, the National Cancer Institute (NCI) reported that CRC is among the leading causes of cancer death in people under 50. Although younger‐onset CRC still remains rarer than in older adults, the acceleration of the trend is what’s particularly worrisome.

What does the new study say?

A major recent investigation by the Mass General Brigham research group analysed nearly 30,000 women under age 50 participating in the long-running Nurses’ Health Study II. They tracked dietary intake and colonoscopy outcomes over more than two decades.

What are the key findings?

As per the study, women who reported the highest consumption of ultra-processed foods (about 10 servings per day) had a 45% higher risk of developing conventional adenomas (precursor growths linked to early-onset colorectal cancer) compared to those with the lowest intake (about 3 servings per day).

What’s striking is that the association held even after controlling for body mass index, diabetes, fibre intake, and other known risk factors.Importantly, no significant link was found between ultra-processed food intake and a different polyp type known as “serrated lesions” in this study. While the study does not prove that UPFs cause bowel cancer, it adds weight to the idea that diet is a meaningful piece of the puzzle.

How might ultra-processed foods (UPFs) contribute to bowel cancer risk?

Researchers propose several biological mechanisms:UPFs often lack fibre and plant-derived protective compounds, which are important for gut health and may regulate inflammation and microbial balance in the colon. Many such foods include additives, emulsifiers, sugar, saturated fat, and refined ingredients that may drive chronic low-grade inflammation in the gut.

A study at the University of South Florida found ultra-processed diets linked to inflammatory lipids in colon tumour tissue and impaired healing responses.Besides, alterations in the gut microbiome (the population of beneficial bacteria) may be induced by UPFs, reducing protective bacterial functions and promoting conditions favourable for tumour growth.In essence, diet patterns dominated by ultra-processed foods may set up a biological environment that makes early-onset colorectal cancer more likely.

What does this mean for prevention and screening?

Given the rapid rise in younger-age cases, health experts are emphasising diet and awareness. For starters, minimising consumption of ultra-processed foods (ready-to-eat packaged snacks, sugary drinks, fast-food items, high-additive foods) could be a proactive step. Swap them with eating more whole foods: vegetables, fruits, whole grains, lean proteins, and foods rich in fibre and phytochemicals — all of which support gut health and reduce inflammation.For those under 50, it’s recommended to stay vigilant about changes in bowel habits, unexplained weight loss, blood in stool, or persistent abdominal discomfort — since early screening may not yet be routine in this age group.