May 23, 2024 – Experts have long warned against eating late at night, especially large meals high in fat or sugar. Now there's one more reason to heed their advice: Eating inside three hours of bedtime on a minimum of 4 days per week may increase your risk of developing colon cancer.
Researchers in a brand new study surveyed 664 individuals who had colonoscopies for cancer screening, and 42% reported being late eaters. This group was 46% more more likely to have an adenoma – a small, noncancerous lesion – discovered through the colonoscopy than those that didn’t eat late.
An adenoma will not be cancer, but an estimated 5 to 10% of them will turn into cancer over time. The risk varies depending on their location within the gastrointestinal tract and size. Doctors search for, measure and count them during a colonoscopy.
“Many other studies deal with What we eat, but not When we eat,” said Edena Khoshaba, lead researcher and medical student at Rush University Medical College in Chicago. “The general advice is to avoid red meat and eat more fruits and vegetables – which is great, of course – but we wanted to see if timing had any effect on us at all.”
Khoshaba and colleagues found that this was the case. Late eaters were 5.5 times more likely to have three or more tubular adenomas compared to people who do not eat late, even after accounting for people's dietary habits. Tubular adenomas are the most common type of polyp in the colon.
So what is the connection between eating late and the risk of colon cancer?
Resetting your internal clock
Eating close to bedtime can throw off your internal clock, or “circadian rhythm.” In this case, it's not the central circadian center in the brain that releases melatonin to make you sleepy at night. Instead, eating late can throw off your “peripheral circadian rhythm,” or the way other parts of your body know how to adjust as day turns to night.
Part of this peripheral system is in our gastrointestinal tract. For example, when you eat late at night, your brain thinks it's night and your gut thinks it's day, Khoshaba said in an interview at this year's Digestive Disease Week conference in Washington, DC.
This is an interesting study, said Amy Bragagnini, spokeswoman for the Academy of Nutrition and Dietetics, when asked to comment on the research. “It is true that eating late in the evening can disrupt your circadian rhythm.”
“In addition, many of my patients have told me that when they eat late at night, they don't always make the healthiest food choices,” Bragagnini said. “Their late-night food choices generally contain more added sugar and fat. This can lead to them consuming far more calories than their body needs.” So late-night eating can also lead to unwanted weight gain.
One unanswered question is whether late eating is in any way related to the increase in colon cancer. in younger patients.
This was an observational study, which is not as powerful as research that randomly assigns people to a group that eats late and one that doesn't eat so late and compares their results over time. Another potential limitation, Khoshaba said, is that people were asked to remember their diet over 24 hours, which may not always be accurate.
Are you keeping your stomach bacteria awake?
Some of the tiny organisms in our gut have their own internal clock that follows a daily rhythm, and what you eat determines how many different types of these organisms are active, Bragagnini said.
“So if you eat foods high in sugar and fat in the evening, it can have a negative impact on your microbiome.”
The next step for Khoshaba and colleagues is a study examining peripheral circadian rhythm, changes within the gut microbiome, and the chance of developing metabolic syndrome.