A new study has shed light on a growing public health concern: the link between ultra-processed foods and early-onset colorectal cancer in women under 50.

Researchers have found that women who consume the most ultra-processed foods face a significantly higher risk—45% greater—of developing precancerous colon polyps, known as colorectal cancer precursors, compared to those who eat the least.

These findings, published in a peer-reviewed medical journal JAMA Oncology, echo mounting evidence from previous studies and reinforce the urgent need for dietary change in younger adults.

Ultra-processed foods, as defined by scientists, are industrially manufactured products packed with additives, refined sugars, unhealthy fats, and artificial ingredients.

Examples abound on supermarket shelves: flavoured yoghurts, processed breads, ready-to-eat breakfast cereals, frozen meals, soft drinks, crisps, and sweets. Such foods are not only convenient but dominate the food supply, with estimates suggesting they make up over 70% of what is available in most countries. This prevalence is reflected in daily consumption habits as well. A 2022 US study reported that nearly 60% of the calories consumed come from ultra-processed sources.

The latest research delved into data from over 29,000 female nurses under 50, participants in the long-running Nurses Health Study II. These women provided detailed records of their food intake over several decades. The researchers focused on ultra-processed food consumption, measuring servings per day and comparing health outcomes. During a median follow-up period of 13 years, the team documented 1,189 cases of early-onset conventional adenomas and 1,598 serrated lesions—both types of precancerous polyps.

What is striking is the magnitude of risk. Women eating approximately 10 servings of ultra-processed foods daily were at far higher risk than those who limited themselves to three servings.

The primary culprits included processed breads and breakfast items, sweetened beverages, sauces and spreads. Interestingly, the association held strong for conventional adenomas but not for serrated lesions, suggesting a nuanced effect depending on polyp type.

Experts highlight that diet is only one piece of a complex puzzle. Rising rates of colorectal cancer in younger adults are a global phenomenon. While obesity and diabetes have long been recognised as risk factors, unhealthy eating patterns are gaining attention for their role in fuelling this trend. Obesity itself is often driven by excess intake of ultra-processed foods, which are energy dense and low in nutrients that promote satiety.

How do these foods drive cancer risk? Scientists point to several mechanisms. First, ultra-processed foods are typically low in dietary fibre, vitamins, polyphenols and other bioactive compounds that protect gut health.

Second, they contain emulsifiers, artificial sweeteners and preservatives that may disrupt the intestinal microbiome—a critical regulator of immunity and inflammation.

Third, excessive intake can lead to chronic inflammation within the gut lining. This pro-inflammatory environment is thought to promote cellular changes that pave the way for polyps and cancerous growths.

The study’s authors caution that their findings should NOT be interpreted as unique to women. The research focused solely on female nurses due to the nature of the available data; however, experts agree that men are also likely at risk.

In fact, national statistics reveal higher incidence and mortality rates from colorectal cancer among men than women. As such, recommendations for dietary change apply across genders.

There are limitations to this study worth considering. The information on food intake was self-reported through questionnaires—a method prone to recall bias and underreporting. The definition of “ultra-processed” was broad and included alcohol, which is independently associated with increased cancer risk. Future research will need to tease apart these factors to arrive at more precise conclusions.

Despite these caveats, the message is clear. Limiting ultra-processed foods aligns with well-established cancer prevention guidelines from leading institutions such as the American Cancer Society (ACS).

These guidelines advocate for a diet rich in whole grains, colourful fruits and vegetables, nutrient-dense foods that support healthy body weight, and minimal consumption of processed meats, sugary drinks and refined grains.

The ACS also emphasises lifestyle factors beyond diet: maintaining a healthy weight throughout life, engaging in regular physical activity, and reducing sedentary time. Experts echo these principles: choose whole grain breads over white loaves; opt for brown rice instead of refined grains; satisfy sweet cravings with fruit rather than confectionery.

It is important not to demonise individual food choices but to focus on patterns over time. Eating a frozen pizza once a month is unlikely to cause harm; the issue arises when such foods become staples rather than occasional treats. Frequency matters—the greater the consumption of ultra-processed foods, the greater the risk.

The implications extend far beyond colorectal cancer. Ultra-processed foods have been linked to a host of health problems including obesity, cardiovascular disease, type 2 diabetes and even mental health disorders. The scale of the problem underscores the urgent need for public awareness and policy intervention.

In practical terms, what does a healthier diet look like? Experts recommend building meals around whole foods: fresh vegetables in a rainbow of colours; fruits packed with antioxidants; whole grains like oats, quinoa and barley; lean proteins such as fish or legumes.

Avoid frequent consumption of processed meats—sausages, hot dogs, bacon—and limit intake of sugar-sweetened beverages.

Alcohol deserves special attention as it is classified as an ultra-processed product in some studies due to its manufacturing process and additive content. Alcohol independently raises cancer risk and should be consumed sparingly if at all.

Policymakers are beginning to take notice of the dangers posed by ultra-processed foods. Food labelling regulations, restrictions on marketing to children and fiscal measures such as taxes on sugary drinks are among strategies implemented in many parts of the world, including Malaysia. Education campaigns targeting schools and workplaces can also play a vital role in shifting dietary habits.

While further research is needed to unravel exactly how ultra-processed foods contribute to colorectal carcinogenesis—especially their impact on gut microbiota and inflammation—the evidence base is growing stronger by the year. Limiting these products and prioritising whole food choices could help reverse rising rates of early-onset colorectal cancer and improve overall population health.

It is essential to empower individuals with knowledge rather than instil fear or guilt. Small changes add up over time: swap a sugary breakfast cereal for porridge; choose water over fizzy drinks; prepare home-cooked meals when possible rather than relying on ready-made options.

The goal is not perfection but progress—a gradual shift towards nourishing habits.

Medical professionals based on general guidelines recommend regular screening for colorectal cancer starting at age 45 or earlier for those with family history or other risk factors. Early detection saves lives and is particularly crucial as cases rise among younger adults who may not consider themselves at risk. Talk to your doctors for more information.

Ultra-processed foods pose a clear threat to gut health and increase the likelihood of developing precancerous polyps in women under 50—a trend likely mirrored in men as well.

The findings underscore the importance of dietary quality for cancer prevention and overall wellbeing. By choosing nutrient-rich whole foods and minimising highly processed options, individuals can take meaningful steps towards protecting their health against one of the most common cancers worldwide.