The Difference Between Soluble and Insoluble Fibers and Their Roles In IBS
Fiber is vital for IBS management and gut health, but not all fiber is actually the same. Fibers can either be labeled as soluble and insoluble. Let’s break each type down, then talk about which one may be best for your IBS symptoms.
Soluble fiber dissolves in water. As it moves through the digestive tract, it dissolves water and forms gel. This helps to speed up digestion by softening the stool, and can help boost beneficial gut bacteria!
Source: oats, beans, lentils, many fruits and vegetables, chia seeds, flax seed, psyllium husk, avocado, and oat bran.
Insoluble water doesn’t dissolve in water. As it moves through the digestive tract, it doesn’t break down or change. Instead, it adds bulk to the stool and helps stool move more quickly through the digestive tract.
Sources: the skin and stalks of many fruits and vegetables, cauliflower, potatoes, wheat bran, nuts, beans, peas, and lentils.
Fiber and IBS
Fiber supports overall digestion, and helps boost good bacteria in the gut. For those with IBS, fiber can help regulate bowel movements, which could help alleviate symptoms. If you are dealing with IBS-C, you may find that insoluble fiber is more helpful. If you are dealing with IBS-D, you may find that soluble fiber is more helpful. However, each person’s tolerance of fiber is very different and there are a few things to consider.
Too much fiber, whether soluble or insoluble may actually trigger symptoms, especially if increased too quickly. Recommended daily fiber intake is 20-30 grams for women and 30-40 grams for men.
It’s not uncommon for both types of fiber to be found in the same foods. If you’re trying to completely avoid one type of fiber, but increase the other, that may be difficult.
Studies have shown more success in IBS symptom relief with soluble fiber, especially supplemental psyllium.
It’s best to work with your dietitian to determine which sources of fiber may be best for you, especially if you are working through a low FODMAP diet. A simple way to start incorporating more fiber into your diet is to start with small portions of soluble fiber at a time from whole foods sources. Your dietitian can help you go from there, or consider whether or not supplemental fiber would be beneficial.