Colon cancer is on the rise among young people – and research points to one major culprit | Devi Sridhar

CAncer was considered to be part of aging: something that has mainly afflicted people over 60 or 70. But although it is always true that the majority of new cancer diagnoses affect those over 70, the model changes in a subtle way. Some cancers are increasingly found among young people.

Take colorectal cancer (intestine): although rates have decreased in those over the age of 60, data show a sharp increase in many developed countries among the under 50s, in what is called early disease.

It is not only due to broader screening or a better diagnosis, and it is not only in a particular country or community. The increase is real and global, going from around 94,700 cases in 1990 to 225,736 in 2019. A study across Europe revealed that for 20-29 year olds, the incidence increased by 7.9% per year between 2004 and 2016, with rates increasing by 4.9% at the same period. Not only does colon cancer increase in each age cohort under 50, but the growth rate is the highest in the youngest group. Modeling suggests that early colorectal cancer could double every 15 years in Australia, Canada, the United Kingdom and the United States.

In England, the NHS intestine cancer screening program covers people aged 50 to 74 by inviting them to free screening every two years. However, this age group excludes young people, who are generally diagnosed only with a late stage when cancer has spread and they are symptomatic.

What causes the rise of young people? We can exclude genetics: it is estimated that 75% of cases are in people without family history or known genetic predisposition. Scientists have started to examine the environmental factors linked to the increase in colon cancer since the 1960s, each generation more likely to obtain cancer than the previous one.

A factor continues to emerge as a major culprit: ultra-transformed foods, with a magazine in 2025 in the nature revised endocrinology highlight the links. These foods, roughly defined as factory-wrapped snacks, ready meals, sweet cereals, carbonated drinks, processed meats and many fast foods, now represent more than half of the average diet in countries like the United Kingdom and the United States.

The evidence is growing: a major study published in the British Medical Journal has examined three major American cohorts to examine the association of ultra-treated food with the risk of colorectal cancer. One of these cohorts involved more than 46,000 men, followed over 24 to 28 years. Compared to the group that has consumed ultra -transformed foods least, the risk of those that have consumed the most developing colorectal cancer – even taking into account nutrition and weight – was 29% higher. The authors conclude that other studies are necessary to understand the physiological mechanisms of the way in which ultra-transformed foods contribute to the development of cancer.

What is interesting is that most of the research has linked ultra-transformed foods to the increase in obesity, which is then a major risk factor for many cancers, the above study indicates the growth of colorectal cancer in those normal weight. Could it be that ultra-grease foods are carcinogenic regardless of someone’s body mass index (BMI)? In other words, are these foods bad for your health even if you have an active lifestyle and are in a healthy weight range?

The regimes rich in ultra-transformed foods have been linked to disruption of insulin signaling, chronic low-grade inflammation and alterations of the intestinal microbiome, which are all mechanisms involved in the development of cancer. What we eat affects the growth of our cells, the functioning of our immune systems and how our intestinal bacteria – which help regulate inflammation and immunity – behave. Emulsifiers, additives and artificial sweeteners commonly found in ultra-transformed foods have been demonstrated in animal studies to promote intestinal inflammation and tumor growth. Meanwhile, the lack of fiber and protective phytochemicals (compounds promoting health found in plants) in these foods can modify the intestinal microbiome required for the body to work optimally.

This has taken decades, but we now accept that tobacco causes lung cancer and that alcohol increases the risk of breast and liver cancer. The next decade can see the inclusion of ultra-transformed foods as a key risk factor in colorectal cancer, especially in young adults. I don’t write this to scare you. Rather, it is a question of thinking about the recent research of rigorous and long -term studies. What we eat more than you think.

If smoking was the villain of the 20th century cancer, eating ultra-adjustment food can be its 21st century counterpart. Science is not yet settled, but it is built quickly. It has often been said that food is medicine. And as we learn more and more, food is prevention. On this note, a 2025 study revealed that regular consumption of yogurt can reduce the risk of developing colon cancer, a subset of colorectal cancer. So, if there is one point to remember to read this: eat more yogurt and fewer ultra-treated foods.