Fiber and Irritable Bowel Syndrome: Finding the Right Balance

Fiber can help IBS—but it can also make it worse. What should you do?

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Fiber has many benefits, and one of them is helping with digestion. Eating fiber-rich foods can help prevent constipation, help you stay full longer, and lead to easier bowel movements—but not for everyone. Fiber can actually create problems for people with irritable bowel syndrome, also known as IBS.

The Fiber Paradox

Constipation is a common symptom of IBS. Normally, doctors recommend eating more fiber to combat constipation. That’s because fiber-rich foods can bulk up your stool and speed up digestion. (Here are other tips to relieve constipation.)

However, this advice can sometimes backfire in people with IBS. Foods with lots of fiber can sometimes worsen notorious IBS symptoms like gas, bloating, and belly pain. That’s because of two key features of IBS:

  • Altered motility, meaning the contractions of the gut may be different than in people without IBS
  • Hypersensitivity, meaning the gut is abnormally sensitive and sends pain signals to the brain, even though nothing is technically wrong

When fiber speeds up digestion, this can make these two characteristics worse. This can thus lead to IBS symptoms.

Two Types of Fiber + How They Affect IBS

Despite this, experts still recommend people with IBS include plenty of fiber in their diet. That’s because there are two types of fiber, and they affect the gut differently.

Soluble fiber attracts water, forms a gel, and slows down digestion. For this reason, it’s often better for people with IBS. You can find soluble fiber in foods like beans, oats, nuts, and some fruits.

Insoluble fiber is the one that speeds up digestion and adds bulk to stool. It’s found in wheat bran, whole-wheat and whole-grain products, and many vegetables. This type of fiber often worsens IBS symptoms, especially in large amounts.

A Healthy Diet for Gut Health

If fiber-rich foods constantly give your gut trouble, it’s often not the answer to avoid fiber altogether. It has numerous health benefits beyond digestion. Tips for including fiber in your IBS diet include:

  1. Choose the type of fiber carefully. Foods with soluble fiber may be more helpful to you than foods with insoluble fiber.
  2. Spread out your fiber intake throughout the day. Have a little fiber at a time with each meal, and be cautious of meals that are loaded in fiber (like those beloved “Buddha bowls”).
  3. Build up your tolerance over time by increasing your fiber intake incrementally.

Finally, talk to a registered dietitian who has experience in IBS if you need more help balancing fiber in your diet. You may benefit from trying the low-FODMAP diet under supervision, or taking another look at your food triggers.