Late Eating Linked to Higher Risk for Colorectal Cancer

Late Eating Linked to Higher Risk for Colorectal Cancer

Written by Damian McNamara, MA

Experts have long advised against eating late at night, especially large meals high in fats or sugars. Now there’s another reason to heed their advice: Eating within 3 hours of bedtime at least 4 days a week could raise the risk of developing colorectal cancer.

Researchers in a new study interviewed 664 people undergoing colonoscopy for cancer screening. Of these, 42% admitted to eating late. This group was 46% more likely to have an adenoma, a small noncancerous lesion, found during the procedure.

An adenoma isn’t cancer, but 5% to 10% can turn cancerous over time. The risk depends on their location in the GI tract and size. Doctors look for, measure, and count them during a colonoscopy.

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“A lot of studies focus on what we eat, not when we eat,” said Edena Khoshaba, lead investigator and medical student at Rush University Medical College in Chicago. “Common advice includes not eating red meat and eating more fruits and vegetables. We wanted to see if the timing of eating matters too."

Khoshaba and her team found it does. Late eaters were 5.5 times more likely to have three or more tubular adenomas compared to non-late eaters, even after accounting for what they ate. Tubular adenomas are the most common type of polyp found in the colon.

What’s the link between late eating and colorectal cancer?

Resetting Your Internal Clock

Eating close to bedtime might disrupt your body’s internal clock, or “circadian rhythm.” This doesn't just involve the central circadian center in the brain, which releases melatonin to make you sleepy. Late eating can mess with your “peripheral circadian rhythm,” or how other body parts adjust when day turns to night.

Part of this peripheral system is in our gastrointestinal tract. For example, eating late makes your brain think it’s nighttime, but your gut thinks it’s daytime, Khoshaba said at this year's Digestive Disease Week conference in Washington, DC.

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This is an interesting study, said Amy Bragagnini, spokesperson for the Academy of Nutrition and Dietetics. “Eating later at night can disrupt your circadian rhythm.”

“Many of my patients have told me that late-night eating often leads to unhealthy food choices,” Bragagnini said. “These choices are usually high in added sugar and fat, causing them to consume far more calories than needed.” Late-night eating can also cause unwanted weight gain.

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It’s still unclear if late eating is linked to rising rates of colorectal cancer in younger patients.

This was an observational study, not as strong as research that randomly assigns people to late or non-late eating groups to compare outcomes. Another limitation, Khoshaba noted, is that participants were asked to recall their diets over 24 hours, which might not be accurate.

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Some gut microorganisms have their own internal clocks that follow a daily rhythm. What you eat affects how many different kinds of these organisms are active, Bragagnini said.

“If your late-night eating includes foods high in sugar and fat, you might be harming your microbiome.”

Khoshaba and colleagues plan to study the peripheral circadian rhythm, changes in the gut microbiome, and the risk of developing metabolic syndrome next.