Researchers strongly advise people with chronic inflammatory bowel disease not to consume a lot of fructose because this diet would increase the risk of colitis while affecting the composition of the gut microbiota.


Fructose is a sugar that is found in fruits in particular and in many vegetables, but also widely used in the food industry, especially in corn syrup also known as fructose-glucose syrup. Numerous studies have shown in recent years that this sugar, when present in the form of glucose-fructose syrup, is responsible for metabolic syndromes such as obesity, insulin resistance and diabetes. Now, a new study suggests that its consumption may also worsen the intestinal inflammation common to chronic inflammatory bowel disease (IBD) which includes Crohn's disease and ulcerative colitis.

Conducted by researchers at Stoony Brook University and published in the journal Cellular and Molecular Gastroenterology and Hepatology, it affirms that the rise in the incidence of IBD coincides with higher levels of fructose consumption in the United States. United and other countries. “Our study demonstrates a direct link between dietary fructose and chronic inflammatory bowel disease, and supports the idea that high fructose consumption may worsen disease in people with the disease. This is important because it would be possible to provide them with advice on their food choices, ”explains Professor David Montrose who conducted the study.

When the inflammation is aggravated

As Inserm explains, IBD is characterized by inflammation of the lining of part of the digestive tract. "In Crohn's disease, this inflammation can be localized at all levels of the digestive system, from the mouth to the anus, although it is most often found in the intestine. In ulcerative colitis, it is localized in the rectum and colon, ”notes the body. These diseases progress by inflammatory outbreaks of extremely variable duration and frequency depending on the patient, alternating with phases of remission. Two typical symptoms are abdominal pain and frequent, sometimes bloody, diarrhea.

Among the risk factors mentioned, genetics and the environment (pollution) but also food even if Inserm specifies "that no food, food group or way of cooking has for the moment been associated with IBD ”. The researchers carried out experiments with three groups of mice suffering from IBD, two of which were fed large amounts of fructose. This habit worsened the severity of the inflammation, especially in the colon and changed the composition of the intestinal microbiota: they noted changes in the types of intestinal bacteria present, their metabolism and also their location in the colon.

What adverse effects on the composition of the intestinal microbiota?

To explain this change, they specify that "additional work has shown that the microbiota is causally linked to the harmful effects of a diet rich in fructose". In addition, the study concludes that “excessive consumption of fructose had a procolitic effect (inflammation of the lining of the large intestine) which can be explained by changes in the composition, distribution and metabolic function of the microbiota”. Note that Inserm also specifies that the intestinal microbiota seems to play an important, but still poorly understood, role in the inflammation characteristic of IBD due to an imbalance in its composition.

If the intestinal microbiota can constitute an interesting therapeutic target in the management of these inflammatory diseases, there is currently no curative treatment, the current drugs allowing a lasting control of the disease. For the next step in their research, the scientists want to develop interventions to prevent the pro-inflammatory effects of fructose and find out how exactly this diet increases colitis. "This second point is particularly important because patients with IBD are at an increased risk of developing colon cancer due to a lifetime of chronic inflammation of the bowel," they conclude.