High-sugar diet can damage gut microbiome, increase IBD risk

A new study led by researchers from UT Southwestern is suggesting a diet high in sugar may contribute to the onset of inflammatory bowel disease (IBD). The study found mice fed high levels of glucose displayed gut microbiome alterations that contributed to inflammation, ultimately leading to the development of colitis.

It’s generally thought that a mix of genetic and environmental factors contribute to the onset of IBD. Scientists are increasingly looking at the role the gut microbiome plays in generating both local intestinal, and systemic, inflammation. And diet is one of those key factors that some researchers suspect could kick off this whole process.

The new study looked specifically at the effect of sugar on the gut microbiome and intestinal inflammation. Groups of mice were fed water solutions with 10 percent concentrations of sucrose, fructose or glucose. After seven days on each different sugar-spiked diet, the animals' microbiomes were genetically sequenced to detect any acute changes.

Each type of dietary sugar was seen to notably alter the animals' gut microbial population. But glucose in particular was found to mediate the most significant disruption. Similar experiments in animals engineered to develop colitis displayed significant increases in symptom severity following the high-glucose diet.

Zooming in on what was actually happening in the animals’ gut revealed increases in populations of bacteria known to produce enzymes that can degrade the mucus layer protecting the lining of the large intestine.

"The mucus layer protects intestinal mucosal tissue from infiltration of gut microbiota," the researchers explain in the study. "Higher abundance of mucus-degrading bacteria, including Akkermansia muciniphila and Bacteroides fragilis, in glucose-treated mice is, therefore, a potential risk for the intestinal mucus barrier.”

Prior research has found intestinal inflammation can be initiated when bacteria and other toxins breach the barrier that lines the large intestine. Further confirming this mechanism, fecal transplant experiments between healthy mice and high-sugar diet mice verified the microbiome alterations do fundamentally influence the severity of IBD.

“Sugar-induced exacerbation of colitis was not observed when mice were treated with antibiotics or maintained in a germ-free environment, suggesting that altered microbiota played a critical role in sugar-induced colitis pathogenesis,” the researchers write in the study. “Furthermore, germ-free mice colonized with microbiota from sugar-treated mice showed increased colitis susceptibility.”

The researchers hypothesize high-sugar diets in humans may be a key factor underpinning the rapid rise in IBD prevalence across Western countries over the past few decades. The level of glucose in high-fructose corn syrup, for example, is suggested as a potential risk factor for triggering common forms of IBD including colitis and Crohn’s disease.

The new research was published in the journal Science Translational Medicine.

Source: UT Southwestern Medical Center