Inflammatory bowel disease: Lack of fiber may be a trigger

Evan Walker
Evan Walker TheMediTary.Com |
a flatlay of a breakfast table featuring tea, grapefruit, oats and berries, crackers, and different kinds of grapes depicting a meal full of fiberShare on Pinterest
Fiber plays an important role in intestinal health. Aleksandra Jankovic/Stocksy
  • Irritable bowel disorder (IBD), which affects around 3 million people in the U.S., is often treated with a low fiber or fiber-free diet during symptom flare-ups.
  • A new study suggests that fiber actually plays a significant role in reducing IBD due to its influence on healthy gut bacteria.
  • The study authors intend to pursue further research looking at the interaction between diet, bacteria, and genetics as a path to reducing the development of IBD.

Irritable bowel disorder (IBD), which can manifest as either ulcerative colitis or Crohn’s disease, develops out of inflammation in the gut or digestive tract, leading to a range of sometimes painful issues with digestion. Scientists have not been able to identify the root cause of this disorder yet, but a recent study suggests a connection between genetics, diet, and gut microbiota that could lead to the development of IBD.

The study, published in Cell Host & Microbe, found that fiber plays a significant role in the interplay between gut microbes and the mucus lining of the digestive system.

Fiber promotes the development of healthy mucus thickness and inhibits inflammation. For people who are born without interleukin-10, an IBD-associated cytokine, IBD typically develops in early infancy or childhood.

The present study shows that in mice lacking interleukin-10, fiber deprivation contributes to the deterioration of the colonic mucus lining, leading to lethal colitis. This suggests that fiber-rich diets may be valuable for individuals with IBD.

An estimated 6 million people worldwide have IBD, and the Centers for Disease Control and Prevention (CDC) says that there are about 3 million people in the U.S. who have it. Industrialized nations have the largest numbers of IBD, and people who immigrate to more industrialized societies and begin incorporating highly processed foods are at risk for it, according to the new study.

A study published last year in Gastroenterology, the official journal of the American Gastroenterological Association, suggested that certain types of dietary fiber can actually make IBD symptoms worse. In that study, researchers found that unfermented dietary β-fructan fibers — which are soluble fibers from fruits and vegetables — caused an inflammatory response in people with IBD whose bodies couldn’t break them down.

Some people who develop IBD, particularly children, are prescribed a formula-based, low-fiber diet known as exclusive enteral nutrition (EEN), and there has been success in reducing gut inflammation with this approach.

No fiber hurts good gut bacteria

The new study used mice who also lacked interleukin-10, and what the researchers discovered was that inflammation was much higher with fiber-free diets. A fiber-free diet was shown to encourage the growth of mucin-degrading bacteria, which consume the mucus layer in the digestive system, reducing the barrier that the mucus provides for the lining of the gut. The mice who ate a high fiber diet had significantly less inflammation.

However, when researchers fed mice the EEN diet formula, some of them had less inflammation than those with a fiber-free diet.

What researchers deduced was that those mice had higher amounts of a fatty acid called isobutyrate, which is produced through fermentation in the gut by “good” bacteria.

Dr. Rudolph Bedford, MD, board certified gastroenterologist at Providence Saint John’s Health Center in Santa Monica, CA, who was not involved in the study, told Medical News Today that lower-fiber diets for people with IBD have not been studied enough for medical professionals to have a blanket approach to them.

“Dietary recommendations for IBD patients have been highly variable, largely due to the dearth of research data available to guide clinical practice,” Dr. Bedford said.

Why IBD patients may be told to limit fiber

“Nonetheless, IBD patients are often instructed to limit their consumption of fiber or residue during an active flare in order to help minimize gastrointestinal distress, particularly when intestinal strictures are suspected,” he said.

Melanie Murphy Richter, a registered dietitian nutritionist and the director of communications for the nutrition company Prolon, who was not involved in the study, told MNT that while less fiber can be advisable during the worst periods of IBD, the long-term effects of a diet high in fiber are important to keep in mind.

“A low-fiber diet may be recommended for people with IBD during acute (active) flare-ups when the inflammation in their gut intensifies. Fiber can be hard to break down, and can therefore exacerbate existing irritation in the gut or gut lining which can contribute to certain symptoms like diarrhea, stomach pain, rectal bleeding, bloating, or even fever. During flare-ups, it’s best to avoid anything that may add to the existing inflammation in the gut.”
— Melanie Murphy Richter

“That said, high fiber diets have shown promising results in the management (and even reversal) of IBD in patients over the long run. This means that when patients are not experiencing acute symptoms or flare-ups, high fiber foods are encouraged to help diversify the composition of the gut which can positively benefit a person’s gut pH, its permeability, and its ability to produce short-chain fatty acids,” Richter said.

Richter said that healthy gut bacteria play a significant role in our immune systems as well as our digestive systems.

“Certain beneficial bacteria in our gut help to strengthen the integrity of our intestinal barrier. This gut lining is what helps to keep pathogenic (harmful) substances out of our gut,” Richter said.

“When the junctures of our gut lining become weak due to the presence of inflammation or other harmful bacteria that can degrade the lining, this leads to intestinal permeability otherwise known as ‘leaky gut.’ Leaky gut, which is often present in IBD and IBS patients, can either be the root cause of inflammation or a symptom of other gut imbalances,” she explained.

Richter added that gut health also can be closely tied to mental health.

“Certain gut bacteria help to produce neurotransmitters like serotonin and dopamine, which are needed for proper brain function, circadian sleep patterns, and the reduction of anxiety and depression,” Richter said. “Without these good bacteria, the signaling between the gut and the brain is negatively impacted, which can lead to mental and emotional disorders.”

Dr. Bedford said that a lack of diversity in the gut lining can make immune systems much weaker.

“Your gut is more vulnerable to diseases when it’s in dysbiosis,” Dr. Bedford said. “Changes to your gut microbiome may occur because the different organisms in your gut are not at the right levels. When the gut microbiome loses its diversity of bacteria, it can increase your risk of getting a chronic disease.

Share this Article