Approximately 3 million people living in the United States have inflammatory bowel disease (IBD), which includes Crohn’s disease and ulcerative colitis. The Western diet – a dietary pattern that is high in unhealthy fats and refined sugar, and low in fiber – has been implicated in the pathogenesis of IBD. A new study suggests that even short-term exposure to a high sugar diet increases susceptibility to ulcerative colitis.

The study involved mice that were fed either regular mouse chow or a diet that was high in sugar (approximately 50 percent sucrose). After two days, the mice were treated with dextran sodium sulfate, a chemical that induces colitis. The mice were then assessed for changes in the diversity of their gut microbiota, disease severity, gut permeability, and short-chain fatty acid (SCFA) concentrations. Increased gut permeability (also known as “leaky gut”) – a condition in which gaps form between the tight junctions of the endothelial cells that line the gut – allows pathogens to leak through the intestinal wall and pass directly into the bloodstream, promoting inflammation. Short-chain fatty acids are products of microbial fermentation that dampen inflammation in the gut.

The mice that ate the high sugar diet exhibited decreased diversity among their gut microbiota, increased gut permeability, and lower concentrations of SCFAs. They were much more likely to develop colitis than the mice that ate the regular chow. These findings suggest that even short-term exposure to a high sugar diet can influence susceptibility to IBD.

• Link to full study.