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A new study suggests that certain types of dietary fiber could worsen symptoms of inflammatory bowel disease in some individuals. Getty Images
  • New research examined how dietary fiber impacts gut microbes in people with inflammatory bowel disease (IBD).
  • Results indicate that certain types of dietary fiber worsen IBD symptoms in some individuals by causing inflammation.
  • The findings from the study could lead to a simple test for detecting IBD flare-ups and personalized dietary recommendations to help people with IBD find relief from their symptoms.

The National Institutes of Health (NIH) and other experts recommend dietary fiber for its important health benefits.

But a new study, recently published in Gastroenterology, suggests that for people living with irritable bowel disease (IBD), certain types of dietary fiber could worsen symptoms.

Currently, IBD affects about 3 million Americans, and rates are currently rising, according to the Centers for Disease Control and Prevention (CDC).

“We know there are health benefits to consuming dietary fibers, and they promote good gut health in healthy individuals, but IBD patients quite frequently complain about a sensitivity when they consume dietary fibers,” study author Heather Armstrong, assistant professor of internal medicine at the University of Manitoba, said in a news release.

“We really wanted to understand the mechanisms behind this.”

For the study, Armstrong and her research team cultured biopsied intestinal cells from people with IBD.

In a lab, researchers introduced a fiber called oligofructose to discover if the gut microbes present in the cells could ferment the fiber, a process necessary for digestion.

They discovered that some people with IBD did not have the right microbes to digest this fiber, and they experienced inflammation.

Researchers concluded that although fiber is “typically” beneficial for those with a healthy level of gut microbes (the microbiome), some dietary fibers can be detrimental for patients with active IBD who lack the right microbes to digest them.

Dr. Henry Jen, a gastroenterologist at Long Island Jewish Forest Hills of Northwell Health in New York, told Healthline the microbiome plays an important role in digestion, including helping to break down food and the synthesis of certain vitamins like vitamin B and vitamin K and essential amino acids.

“It also plays a critical role in immune function by acting as a healthy barrier to protect the body from harmful pathogens,” he noted.

Jen explained that fiber is found in a large variety of foods, including certain vegetables, fruits, and grains.

“Well-known sources of dietary fiber include beans and whole-wheat products, but there are many other foods rich in fiber that are not always thought of,” he said. “Including avocados, peas, broccoli, apples, oranges, and almonds.”

Jen emphasized that most adults should aim for between 25 to 34 grams of fiber per day, which echoes the recommendation for dietary fiber intake in the 2020–2025 Dietary Guidelines for Americans.

“Increased dietary fiber intake has been associated with a decreased risk of cardiovascular disease, stroke, diabetes, and may even decrease the risk of colon cancer,” he continued.

The study authors said they’re currently working to develop a stool test to examine microbes in each IBD patient’s gut to predict who might have an adverse response.

The goal is to tailor dietary recommendations and treatment for each patient based on the results.

“By creating this stool test, we are hoping to be able to tell you how to adjust your diet to prevent flares or further worsening,” study co-author Dr. Eytan Wine, a pediatric gastroenterologist, and professor of pediatrics and physiology in the Department of Pediatrics at the University of Alberta, said in a statement.

“It’s a dynamic situation so it’s possible that a certain food you should avoid now, in a few months you’ll be OK to eat that again.”

While fiber aids with digestion and has anti-inflammatory effects in most healthy people, researchers found when particular fibers remain “unfermented,” they actually increase inflammation, and might worsens symptoms for some IBD patients.

Study findings indicate that especially hard-to-digest fibers for people with missing or malfunctioning gut microbes include those from:

  • artichoke
  • garlic
  • asparagus
  • bananas

According to Jen, IBD typically manifests with gastrointestinal (GI) symptoms like diarrhea, abdominal pain, and blood or mucus in the stool.

“Patients, if left untreated, have higher risks of colon cancer,” he cautioned.

“They also can develop intestinal blockages or even ruptures and can be associated with non-GI symptoms too, such as rashes, arthritis, and eye inflammation,” Jen continued.

“Patients are more at risk of poor absorption and malnutrition and may experience fatigue and weight loss.”

Jen said that our understanding of the gut microbiome and IBD is constantly evolving.

“This study points to an altered microbiome as the potential cause of why some patients with IBD respond differently to dietary fiber,” he explained.

Jen added that there has already been a strong link established between IBD and alterations in a patient’s gut microbiome.

“Some patients with severe IBD can even be candidates for a complete overhaul of their gut microbiomes with a fecal transplant,” he said.

New research shows that people with IBD are at increased risk of flare-ups if they’re missing the microbes needed to digest certain types of dietary fiber.

Experts say that a new test to find out who’s at risk could allow those living with IBD to reduce their odds of an adverse reaction.

People with severe IBD may even be candidates for a fecal transplant to help repair their gut microbiome.