Unveiling the Link Between Ultraprocessed Foods and Colon Cancer

According to the National Cancer Institute, colon cancer is the second leading cause of cancer-related deaths in the United States in 2024.¹ While it’s a cause for concern, the good news is that research is constantly uncovering the causes of this disease, allowing you to prevent it. One area of growing interest is the connection between your gut health and cancer risk, particularly the composition of the food you eat.

Your gut is a fascinating, complex ecosystem teeming with trillions of bacteria, both helpful and harmful. These tiny residents play a crucial role in digestion, nutrient absorption and even your immune system.

Through various processes and interventions, your body maintains a delicate balance, with the good bacteria keeping the bad ones in check. But when this balance gets disrupted, particularly due to consumption of vegetable oils, chronic inflammation arises, contributing to various health problems, including colon cancer.

Decoding Your Diet — The Rise of Ultraprocessed Foods

The ultraprocessed foods you see in your grocery store aisles, like instant noodles, frozen pizzas and pre-packaged snacks, have undergone extensive changes from their natural state, and often contain added sugars and artificial flavors. While convenient, these hidden ingredients negatively impact your gut bacteria and overall health. Particularly harmful are vegetable oils, which fuel the rise of colon cancer in America.

In a study published in the journal Gut, researchers have shown a correlation between intake of ultraprocessed foods high in certain vegetable oils and an increased risk of colorectal cancer (CRC).² To start, they likened CRC as a “chronically inflamed, poorly healing wound.” This contrasts with normal wound-healing, which is marked by a regular inflammatory process, but followed by a pro-resolution period.

Following this framework, they gathered 81 human CRC samples alongside normal samples for comparison. Using liquid chromatography and tandem mass spectrometry, they noted that CRC samples have defective “lipid class switching” that lean toward a proinflammatory state.³

In an interview for Scientific American, Dr. Timothy Yeatman, one of the co-authors of the study, explains this concept:

“Resolving lipids, or proresolving lipids, were only recently discovered by Charles Serhan of Harvard University. And he described something called ‘lipid class switching,’ which means that the body, when it undergoes normal healing, will switch from the inflammatory phase to the resolving phase.

He basically found that there are a number of these lipids — primarily omega-3 derivative lipids — that lead to resolution of inflammation. But inflammation, unchecked, can lead to cancer.”⁴

The Scientific American report also explains that chronic, rampant inflammation damages normal cells and impairs their ability to fight cancerous growth. And according to Yeatman, the high intake of omega-6 is a strong contributor.⁵ Explaining the class switching process further under a diet high in omega-6:⁶

“During the initial phase of normal wound healing, prostaglandins and leukotrienes (LTs) are synthesised and orchestrate an anti-inflammatory response wherein PGE2/PGD2 induce ALOX15 expression causing a switch from proinflammatory mediators (LTs) to pro-resolving lipid mediators (lipoxins, resolvins, maresins, protectins and maresins).

This process is called lipid mediator class switching (LCS) and has been identified as an essential mechanism for resolving inflammation. This LCS process appears to be deficient in CRC, resulting in the majority of tumours sustaining a chronic inflammatory state.”

Now, let’s talk about the vegetable oils lurking in many processed foods — canola, corn and soybean oil are all common examples. These oils are high in linoleic acid (LA). While LA is not inherently harmful because your body needs some of it, it becomes problematic when consumed in excess. The issue is vegetable oils are often used for frying, baking and adding flavor to the majority of processed foods, causing the modern Western diet to be overloaded with LA.

The Gut Microbiome — A Balancing Act

Your gut is like a bustling city with diverse residents. You have good bacteria acting as friendly shopkeepers to keep things running smoothly. Then there are the “bad bugs,” like mischievous pranksters, who cause trouble when they get out of control. Maintaining a healthy gut microbiome is all about ensuring the good bacteria have the upper hand.

Chronic inflammation, often triggered by an imbalance in the gut bacteria, contributes to various metabolic diseases.⁷ Think of it like a constant, low-grade fire in your city. This inflammation damages surrounding tissues and creates a breeding ground for disease.

So, how does diet impact this delicate ecosystem? When you consume a diet rich in ultraprocessed junk foods high in omega-6s, you’re nourishing the bad bugs. They thrive while the good bacteria struggle to compete. This disruption in the gut microbiome leads to an inflammatory environment, increasing the risk of colon cancer.