Some Ultra-Processed Foods May Not Increase Bowel Cancer Risk, Study Suggests

Not all ultra-processed foods (UPFs) are linked to an increased risk of bowel cancer, and some common pantry staples may even reduce the likelihood of developing the disease, according to a recent study published in the journal PLOS Medicine. The findings suggest that items like cereals, flavored yogurts, supermarket bread, and baked beans could potentially lower the risk of bowel cancer by up to 28 percent.

This research, conducted by US experts, examined the diets of 461,682 adults in the United States aged between 50 and 71 over an 18-year period. During this time, 10,075 cases of bowel cancer were diagnosed. The study noted that approximately half of the participants' caloric intake came from ultra-processed foods.

While previous studies have consistently found a link between UPFs and an increased risk of bowel cancer, this new research suggests a more nuanced relationship. The study's authors found that individuals consuming the highest amounts of UPFs overall were not more likely to develop bowel cancer than those who consumed the least. However, a breakdown of specific food categories revealed differing associations.

Consumption of processed meats, such as hot dogs and bacon, was linked to an eight percent higher chance of developing bowel cancer. In contrast, ultra-processed dairy products, including flavored and sugary yogurts, were associated with a 25 percent lower risk. Similarly, an extra daily serving of supermarket wholemeal bread was linked to a 13 percent reduced risk, and an additional 10 grams of fiber per day from processed fibrous foods like baked beans was associated with a 28 percent drop in risk.

The researchers proposed that these differences may be due to the nutritional content of certain UPFs. For instance, breakfast cereals, wholemeal bread, and baked beans are often high in fiber, a nutrient known to reduce bowel cancer risk.

Despite these intriguing findings, the study authors emphasized that the research has limitations. The study primarily involved older adults, and the findings may not be generalizable to younger populations. Experts not involved in the study also urged caution when interpreting the results.

Dr. Rosiered Brownson-Smith of King's College London noted that the study supports the idea that UPFs should not be treated as a single, uniform category. However, she cautioned against generalizing the findings to younger individuals, particularly given the documented rise in early-onset bowel cancer.

Dr. Aisling Daly from Oxford Brookes University suggested that by identifying specific UPFs with different risk associations, the study might help to alleviate some concerns about the broad category of UPFs. Professor Gunter Kuhnle of the University of Reading stated that the findings were not surprising, reinforcing the known association between a diet low in fiber and high in processed meat and an increased cancer risk.

Separately, a study published in JAMA Network Open on the same day found that individuals consuming the highest amounts of UPFs were 40 percent more likely to have signs of vascular brain injury detected on MRI scans. This type of injury occurs when the brain is damaged due to problems with its blood vessels. The authors of that study also noted that their research was observational and could not establish a cause-and-effect relationship, but indicated that their findings extend previous research on UPF intake and adverse brain health outcomes.