Soluble vs. Insoluble Fiber: Selecting the Ideal One for IBS

Suppose you suffer from irritable bowel syndrome (IBS). In that case, you know the importance of a balanced diet, and understanding the difference between soluble and insoluble fiber can help you find that balance. But what is the difference between soluble and insoluble fiber? Let's dive into dietary fibers, explore how they affect our bodies, and learn the art of knowing the right type for our needs. Whether you're just starting your IBS dietary journey or looking for ways to supplement it, read on to learn more about soluble vs. insoluble fiber.

What is Soluble Fiber?

These are the type of food items that absorb water and turn into a gel-like substance inside the intestine. Such food items help you achieve a thick stool and make it soft and easy to pass. On the contrary, insoluble fiber food items do not absorb water yet add bulk to the stool without making it softer. Thus, it is imperative to understand both types of fiber and their importance for maintaining a healthy digestive system.

There are two types of soluble fiber, pectins, and mucilage. Pectins are found in citrus fruits, apples, and carrots. Mucilage is found in oats, barley, psyllium husk, and flaxseeds. Both pectins and mucilage can help to reduce constipation by adding bulk to the stool and keeping it soft. In addition, soluble fiber can also help to reduce diarrhea by absorbing excess water in the intestine. 

What is Insoluble Fiber?

Insoluble fiber is the indigestible part of plant foods that helps add bulk to our stool and prevents constipation. Some popular examples are wheat bran, vegetables, whole grains, and nuts. Unlike soluble fiber, they do not dissolve in water and do not get easily broken down by enzymes in the gut. So, they pass through our digestive system relatively unchanged.

While insoluble fiber is an important part of a healthy diet, it can be problematic for people with irritable bowel syndrome (IBS). That's because insoluble fiber can act like a sponge, soaking up water and making stool harder to pass. If you have IBS, you may need to limit your intake of insoluble fiber or choose foods lower in this type of fiber.

The Benefits of Soluble Fiber

The benefits of soluble fiber are many and varied. For one, it helps maintain a regular bowel system, helps reduce cholesterol and blood sugar levels, and is believed to help prevent some types of cancer. Additionally, soluble fiber can help you feel fuller longer, aiding in weight loss or weight management. And last but not least, it's good for your overall health!

The Benefits of Insoluble Fiber

Insoluble fiber helps to relieve constipation and diarrhea. It also reduces the risk of diverticulitis-a condition that occurs when pockets in the lining of the intestine become inflamed or infected. Insoluble fiber can help reduce the risk of diverticulitis by adding bulk to the stool and keeping the intestine clean. Lastly, it slows down sugar absorption in the intestine to help you control blood sugar levels.

Fiber on a Low-FODMAP Diet

If you follow a low-FODMAP diet, you may wonder if you can still get enough fiber. Fiber is an important nutrient for many reasons, including promoting regularity and helping to lower cholesterol levels.

Fortunately, plenty of high-fiber foods are also low in FODMAPs.

Some great high-fiber, low-FODMAP options include lentils, quinoa, buckwheat, oats, chia seeds, flaxseeds, fruits (such as raspberries and bananas), and vegetables (such as broccoli and carrots). The aim is to get at least 25 grams of fiber per day. Talk to your doctor or dietitian about supplement options if you're having trouble meeting your fiber needs on a low-FODMAP diet.

How to choose the right type of fiber for you

Each type of fiber has different benefits for people with irritable bowel syndrome (IBS). Go for soluble fiber if you want to help with diarrhea by forming a thick gel that slows digestion. It can also help to reduce gas and bloating by trapping carbohydrates that gut bacteria would otherwise ferment.

On the other hand, insoluble fiber food items would be your ideal bet if you want to add bulk to the stool to reduce constipation and prevent hard stools that are difficult to pass.

The best way to get both types of fiber is from food sources. However, if you find that you need more from your diet, supplements containing either soluble or insoluble fiber are available. Be sure to speak with your doctor before starting any new supplement, as they can cause side effects in some people with IBS.

Fermentable vs. Nonfermentable Fiber Food

There are two main types of dietary fiber, fermentable and nonfermentable. Fermentable fiber is broken down by the bacteria in our gut, while nonfermentable fiber passes through our system relatively unchanged. Each type of fiber has various health benefits.

Fermentable Fiber

Fermentable fiber includes soluble fibers like pectin, gums, and mucilage and insoluble fibers like resistant starch and lignin. The bacteria ferment this type of fiber in our gut, which produces short-chain fatty acids that can be used by our cells for energy. Soluble fibers can also help to lower cholesterol levels and regulate blood sugar levels.

Nonfermentable Fiber

Nonfermentable fiber includes cellulose, hemicellulose, and lignin. This type of fiber does not break down in our gut, but it does add bulk to our stool and helps to keep us regular. Nonfermentable fiber is important for maintaining a healthy gastrointestinal tract. 

So which type of dietary fiber is better for you? It depends on your individual needs. Soluble fibers may be a good choice if you're looking to lower cholesterol or regulate blood sugar levels. Nonfermentable fibers are a good option if you're trying to maintain a healthy gastrointestinal tract or prevent constipation.


We hope this small knowledge supplement has helped you understand the key differences between soluble and insoluble fiber, as well as how to ensure you're getting the right kind for your IBS. Remember that even if it takes a bit of experimentation to find out which type of fiber works best for you, it can be beneficial in helping manage your symptoms. If you need help finding additional resources on dietary changes that could benefit your IBS, don't hesitate to talk to your doctor or dietitian.

Updated on: 20-Jan-2023


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