Fructose in diet may exacerbate inflammatory bowel disease

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A study in mice suggests that a diet high in the sugar fructose worsens inflammatory bowel disease (IBD). Changes in gut bacteria appeared to mediate the effect. IBD is an umbrella term for several conditions that feature chronic inflammation of the digestive tract. The two most common types of IBD are ulcerative colitis and Crohn’s disease. Common symptoms of IBD include: persistent diarrhea, stomach pain, rectal bleeding, bloody stools, unexplained weight loss and fatigue.
The incidence of IBD has been increasing worldwide. According to the Centers for Disease Control and Prevention (CDC), the number of adults receiving an IBD diagnosis each year in the United States increased from 2 million in 1999 to 3 million in 2015. Previous research in animals has found that a diet high in fructose can damage the colon and cause inflammation. This finding suggests that a higher fructose intake may have played a role in the increased incidence of IBD in recent decades. Population studies have not always shown an association between refined sugar intake and IBD. One large study found no association between any specific dietary pattern and IBD. However, the results showed that a diet high in sugar and soft drinks did increase the risk of ulcerative colitis in cases where vegetable intake was low. Manufacturers add high fructose corn syrup to sodas, candy, baked goods, and other processed foods. The consumption of fructose has increased by almost one-third in the U.S. over the past 3 decades, according to some estimates. The increasing incidence of IBD parallels higher levels of fructose consumption in the U.S. and other countries.
The researchers wanted to investigate whether fructose worsens inflammation in mouse models of IBD. They also tested the idea that changes in the community of microorganisms living in the gut, known as its “microbiota,” mediate the inflammatory effects of fructose.
Our findings provide evidence of a direct link between dietary fructose and IBD and support the concept that high consumption of fructose could worsen disease in people with IBD. This is important because it has the potential to provide guidance on diet choices for IBD patients — something that is currently lacking. The scientists performed a range of experiments with the aim of investigating the effects of a high fructose diet on three different mouse models of IBD.
In the first model, which uses a chemical called dextran sodium sulfate to provoke the kind of inflammatory response that occurs in IBD, a high fructose diet increased the severity of this inflammation. In contrast, a high glucose diet did not exacerbate inflammation.