“Overall, people with IBD should incorporate all types of fiber in their diet.” That said, if you’re experiencing a flare, it helps to limit certain types of fiber until your symptoms improve. These include:
Insoluble Fiber
Insoluble fiber does not hold onto water and is often referred to as “roughage.” It helps push food through the GI tract more quickly, resulting in a laxative effect. Insoluble fiber tends to be less fermentable by our gut microbes than soluble fiber, so while it is still a healthy component of the diet, its main role is to provide bulk to stool rather than feeding good gut microbes.
“Insoluble fiber or fiber consumed in large quantities during active inflammation can [worsen] symptoms by irritating the gut lining and increasing stool bulk, which may lead to discomfort or diarrhea,” says Dr. Nahar.
You can find insoluble fiber in:
Wheat bran
Whole nuts and seeds
Leafy greens
Legumes
Quinoa
The skins of fruits and vegetables
Those actively experiencing IBD symptoms often benefit from reducing their intake of insoluble fiber and replacing it with foods rich in soluble fiber instead. For example, swapping out berries for bananas, or opting for oatmeal rather than bran cereal.
Still, this is highly dependent on personal factors, Prieto-Jimenez says. “When someone is going through an IBD flare-up, adjusting fiber depends on symptoms, disease location, and type to define the best individualized plan,” she says.
FODMAPs
“FODMAP” is an acronym that stands for “fermentable oligosaccharides, disaccharides, monosaccharides, and polyols,” scientific terms for fibers that are highly fermentable by our gut bacteria. As a by-product of fermentation, gut bacteria produce gas and draw water into the intestines, triggering GI symptoms for some. Foods high in FODMAPs include:
Legumes
Wheat
Lactose-containing dairy
Processed and marinated meat
Certain fruits
Vegetables like onions, garlic, artichokes, mushrooms, and cauliflower
Fruits, especially stone fruits like peaches, avocado, and cherries
Sugar substitutes
Everyone’s FODMAP tolerance is unique, so it’s helpful to work with a registered dietitian to pinpoint which FODMAPs may trigger your symptoms specifically and which ones you should limit during a flare.
It’s also important to note that while avoiding FODMAPs can improve functional irritable bowel syndrome (IBS)-like symptoms for some, this doesn’t necessarily equate to a reduction in GI inflammation, and interventions like the low FODMAP diet, for example, have not been shown to reduce IBD inflammation. (The low FODMAP diet is an elimination diet used to identify dietary triggers in those with IBS. Although IBS and IBD are different conditions, they have some overlapping symptoms.)
“A low-FODMAP diet should not be used when someone has active IBD,” adds Prieto-Jimenez. It’s also not advisable to start the low FODMAP diet without guidance from a dietitian, as it’s highly nuanced and can be restrictive. Avoiding high FODMAP foods for a prolonged period can negatively impact the gut microbiome.
