Here’s why sugar wreaks havoc on gut health, worsens inflammatory bowel disease

PITTSBURGH — There can be a lot of inconsistent dietary advice when it comes to gut health, but those that says that eating lots of sugar is harmful tend to be the most consistent of them all. Scientists from the University of Pittsburgh are now showing that consuming excess sugar disrupts cells that keep the colon healthy in mice with inflammatory bowel disease (IBD).

“The prevalence of IBD is rising around the world, and it’s rising the fastest in cultures with industrialized, urban lifestyles, which typically have diets high in sugar,” says senior author Timothy Hand, Ph.D., associate professor of pediatrics and immunology at Pitt’s School of Medicine and UPMC Children’s Hospital of Pittsburgh. “Too much sugar isn’t good for a variety of reasons, and our study adds to that evidence by showing how sugar may be harmful to the gut. For patients with IBD, high-density sugar — found in things like soda and candy — might be something to stay away from.”

In this study, researchers fed mice either a standard or high-sugar diet, and then mimicked IBD symptoms by exposing them to a chemical called DSS, which damages the colon.

Shockingly, all of the mice that ate a high-sugar diet died within nine days. All of the animals that ate a standard diet lived until the end of the 14-day experiment. To figure out where things went wrong, the team looked for answers inside the colon. Typically, the colon is lined with a layer of epithelial cells that are arranged with finger-like projections called crypts. They are frequently replenished by dividing stem cells to keep the colon healthy.

“The colon epithelium is like a conveyor belt,” explains Hand in a media release. “It takes five days for cells to travel through the circuit from the bottom to the top of the crypt, where they are shed into the colon and defecated out. You essentially make a whole new colon every five days.”

Gut health: Intestines sketch with gut bacteria
(© T. L. Furrer –

This system collapsed in mice fed a high-sugar diet

In fact, the protective layer of cells was completely gone in some animals, filling the colon with blood and immune cells. This shows that sugar may directly impact the colon, rather than the harm being dependent on the gut microbiome, which is what the team originally thought.

To compare the findings to human colons, the researchers used poppy seed-sized intestinal cultures that could be grown in a lab dish. They found that as sugar concentrations increased, fewer cultures developed, which suggests that sugar hinders cell devision.

“We found that stem cells were dividing much more slowly in the presence of sugar — likely too slow to repair damage to the colon,” says Hand. “The other strange thing we noticed was that the metabolism of the cells was different. These cells usually prefer to use fatty acids, but after being grown in high-sugar conditions, they seemed to get locked into using sugar.”

Hand adds that these findings may be key to strengthening existing links between sweetened drinks and worse IBD outcomes.

“I think that we need to investigate more deeply what diets are going to benefit patients who have intestinal damage, whether that be from IBD or from radiation therapy to treat colon cancer,” says Hand. “It’s about a nutraceutical approach to colon damage, or the idea of finding the right diet for a particular patient.”

The findings are published in the journal Cellular and Molecular Gastroenterology and Hepatology.

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About the Author

Shyla Cadogan, RD

Shyla Cadogan is a DMV-Based acute care Registered Dietitian. She holds specialized interests in integrative nutrition and communicating nutrition concepts in a nuanced, approachable way.

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