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Can intermittent fasting protect gut health as we age?

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Intermittent fasting may preserve gut health as an individual ages, according to a new study in mice. Image credit: NICK VEASEY/SCIENCE PHOTO LIBRARY/Getty Images.
  • Intermittent fasting is one of the most popular diets or eating patterns in the United States. 
  • Recent studies show intermittent fasting may offer other health benefits than just weight loss such as protection against type 2 diabetes, cardiovascular disease, and cancer. 
  • A new study found intermittent fasting may also help protect the small intestine as it ages, via a mouse model.

In a new study recently presented at the annual meeting of the American Physiology Summit in Long Beach, CA, researchers from the Arizona College of Osteopathic Medicine at Midwestern University in Downers Grove, IL, reported that intermittent fasting may also help protect the gastrointestinal system — mainly the small intestine — as it ages. 

Researchers used a mouse model that they had genetically modified to accelerate aging. One group of mice had food available at all times, while the other group only had access to food during alternating 24-hour cycles.

After 8 months, scientists found that the mice on the fasting plan gained less weight and had structural changes in their small intestines associated with better glucose control and decreased inflammation.

“Our study suggests that intermittent fasting is a beneficial dietary practice to control weight gain, improve blood glucose levels, and promote positive intestinal effects by reducing inflammation and oxidative stress while altering intestinal structure,” Spencer Vroegop, a second-year student at the Arizona College of Osteopathic Medicine at Midwestern University and first author of this study, told Medical News Today.

How does aging affect the small intestine?

For this study, researchers focused on a specific part of the small intestine called the jejunum Trusted Source PubMed Central Highly respected database from the National Institutes of Health Go to source

The jejunum is the second of the small intestine’s three regions responsible for continuing food digestion and absorbing nutrients and water from food so it can be used in other areas of the body. 

“As mammals age, there are inherent damaging changes to the morphology of the small intestine that impact the ability to absorb nutrients and maintain its structure,” Vroegop explained.

“Our study suggests that an intermittent fasting diet may help prevent these age-related changes by returning the jejunum to a ‘younger’ version of itself,” he told us.

Effects of intermittent fasting in males vs. females

At the conclusion of the study, researchers observed that improvements in the health and appearance of the small intestine were more pronounced in female mice than in male mice.

Female mice also had the greatest refinement in how sugars were transported. 

However, scientists found that the impact of intermittent fasting on blood sugar levels was stronger in male mice than in female mice. It is unclear, however, if the sex differences in sugar metabolism in mice also apply to humans.

For the next phase in this research, the scientists plan to delve deeper into what might be behind these gender-specific differences.

Research in humans needed

After reviewing this study, Mir Ali, MD, a bariatric surgeon and medical director of MemorialCare Surgical Weight Loss Center at Orange Coast Medical Center in Fountain Valley, CA, not involved in the research, told MNT he was not surprised by its findings, as there have been reports of other benefits to intermittent fasting. 

“So it’s not surprising that it shows some changes in the gut in the mice that they experimented on,” Ali said. 

However, as this study was conducted in mice, Ali told us the next steps should be evaluating for similar changes in human subjects with future studies. 

“Put certain patients on certain fasting periods and see which is the most beneficial because there’s not a lot of comparison between fasting,” he advised.

“There’s comparison looking at intermittent fasting versus other diets, but not what type of intermittent fasting has the most benefits,” Ali added.

What to know about intermittent fasting

Intermittent fasting is a timed schedule of eating at certain periods of time and then withholding food for an extended duration, a period known as fasting, when a person abstains from eating.

Several different methods of intermittent fasting are determined by how many hours or days the fasting lasts for, how many hours or days a person can eat, and how many calories they can consume. 

Some of the more popular patterns of intermittent fasting include time-restrictive eating, where the fast lasts 12, 14, or 16 hours, and the eating period stretches over the remaining hours of the day, or the 5:2 method, where a person consumes only 500 calories for 2 days of the week and then eats normally for the remaining 5 days. 

About 12% of American adults follow intermittent fasting as their diet or eating pattern of choice, according to the International Food Information Council’s 2023 Food and Health Survey, making it currently one of the most popular diets. 

In addition to weight loss Trusted Source PubMed Central Highly respected database from the National Institutes of Health Go to source , recent studies show that intermittent fasting may offer other health benefits, such as protection against type 2 diabetes Trusted Source PubMed Central Highly respected database from the National Institutes of Health Go to source , cardiovascular disease Trusted Source PubMed Central Highly respected database from the National Institutes of Health Go to source , and cancer Trusted Source PubMed Central Highly respected database from the National Institutes of Health Go to source , as well as against gastrointestinal issues, such as inflammatory bowel disease (IBD) Trusted Source PubMed Central Highly respected database from the National Institutes of Health Go to source and ulcerative colitis Trusted Source PubMed Central Highly respected database from the National Institutes of Health Go to source

Is intermittent fasting safe?

Rudolph Bedford, MD, a board-certified gastroenterologist at Providence Saint John’s Health Center in Santa Monica, CA, not involved in the recent study, told MNT that while intermittent fasting may help gastrointestinal health in some ways, it could also potentially cause issues.

“Essentially, the body needs to be able to work through calories over periods of time and not on an intermittent basis, so to speak,” Bedford explained. “Therefore, one does need to eat.” 

“I think what some people will do is that they’ll […] eat over several days, and then they’ll fast for a couple of days, limiting their calorie intake to maybe 500 calories for the whole day,” he continued. “That I have no issues with. I think that longer periods of fasting may be somewhat deleterious to your system and your body.” 

Where intermittent fasting may be helpful, Bedford said, is in protecting against the development of conditions such as diabetes and irritable bowel syndrome (IBS)

And, he added, by engaging in intermittent fasting, “[y]ou can essentially give the body a break, so to speak, in terms of having to work and burn through calories or absorb nutrients in many ways.”

What type of intermittent fasting is best? 

For someone starting intermittent fasting, the amount of methods can be a bit overwhelming and confusing. 

When asked which intermittent fasting method is best, Ali said there is no one best way because what works for one person may not work for another. 

Nevertheless, he advised:

“I suggest patients start with the easier ones like fasting overnight — stop eating after 8 p.m. and not eat until 8 a.m. the next day. That’s a little easier to do because a big part of that time you’re sleeping, so you don’t notice the hunger as much. And then you can increase that to longer periods of time.” 

“Some people find benefit from doing intermittent fasting on a daily basis where you eat one day and don’t eat another day, and that’s fine, too,” Ali added. “It’s trial and error to see which [method] works best for you.” 

This article originally appeared on Medical News Today.

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