How do ultraprocessed foods affect the gut?

Walk into a typical supermarket in the United States, and much of what you see — breakfast cereals, frozen meals, processed meats, sodas — is considered ultraprocessed food.

- Alice Callahan

These products, typically defined as foods and drinks made with ingredients you wouldn't find in a home kitchen, make up more than half of the calories people in the United States consume and have been associated with various health conditions including obesity and Type 2 diabetes. Now emerging evidence has also linked ultraprocessed foods to poor gut health, said Kevin Whelan, a professor of dietetics at King's College London.

Over the last few years, a growing body of research has suggested that people who eat more ultraprocessed foods have higher risks of developing certain conditions that affect the stomach and the intestines.

The most consistent link, Whelan said, is with Crohn's disease — an often-debilitating inflammatory bowel disease that causes abdominal pain, severe diarrhoea, fatigue and weight loss.

In a review published in 2023, scientists found that adults who consumed the most ultraprocessed foods had a 71 per cent greater risk of developing Crohn's disease than those who consumed the least.

Other research has linked ultraprocessed foods with increased risks of irritable bowel syndrome, stomach ulcers and colorectal cancer. In a study of more than 29,000 female nurses published this month, researchers reported that those who consumed the most ultraprocessed foods were 45 per cent more likely to develop a certain type of precancerous colorectal polyp than those who consumed the least.