Fiber is good for you, except when it’s not

People suffering from inflammatory bowel disease may soon have access to personalized dietary guidelines to help them feel good, thanks to new research published in gastroenterology how dietary fiber affects the disease.

The research team discovered that certain types of fiber cause an inflammatory response in some patients, resulting in worsening symptoms.

They are now working to develop a stool test to examine the microbes found in each patient’s gut to predict who will show the negative reaction so they can tailor diet recommendations and treatments for individual patients.

Approximately 0.7 percent of Canada’s population, or one in 150 people, has IBD, including Crohn’s disease and ulcerative colitis, and that number is predicted to rise to 1 percent by 2030.

IBD symptoms can include abdominal pain, diarrhea, bloody stools, weight loss, late puberty, and a long-term risk of colon cancer. The exact cause is unknown, but some risk factors include genetics, diet, environmental factors, and changes in gut microbes.

“We know that consuming fiber has health benefits and promotes good gut health in healthy individuals, but IBD patients quite commonly complain of sensitivity when consuming fiber,” says Heather Armstrong, who began the research as a postdoctoral researcher at the U of A and is now an Assistant Professor of Internal Medicine at the University of Manitoba and Canada Research Chair in Integrative Bioscience. “We really wanted to understand the mechanisms behind it.”

“By creating this stool test, we hope to be able to tell you how to adjust your diet to prevent flare-ups or further deterioration,” says Eytan Wine, professor in the U of A’s School of Medicine and Dentistry is a dynamic situation, so it is possible that you should avoid a certain food now, in a few months you can eat it again.”

Not all fibers are born equal

Unlike most foods we eat, fiber is not digested in the small intestine. Tiny bacteria and fungi, or “microbiota,” in the colon or colon produce enzymes to ferment fiber. Chemically, fiber can be a short chain of sugars, like pectin, found in citrus fruits, or a very long and branched structure that’s harder to ferment.

Researchers have found that certain types of fibers found in foods such as artichokes, chicory roots, garlic, asparagus and bananas are particularly difficult to ferment when certain microbes are absent or malfunctioning, as is often the case in IBD patients is.

Fiber has beneficial anti-inflammatory effects and aids in digestion in most healthy people, but researchers have found that selected unfermented fiber increases inflammation and worsens symptoms in some IBD patients.

“We want to start by figuring out why 20 to 40 percent of patients experience hypersensitivity,” says Armstrong, “while in the other half of patients, this fiber can actually benefit health and protect against disease and have very beneficial effects.”

Wine and Armstrong both warn that the new dietary guidelines will not replace drug treatments, but should complement them so patients can avoid flare-ups and get back into remission faster if they have inflammation.

“I have IBD myself, so I often have research questions that I want answered personally,” says Armstrong. “If we can find a way to reduce diet-related inflammation, we may be able to alleviate some of the burden of disease and even save some people from progressing to a more serious disease.”