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Navigating Fibre with IBS

Feature, Gut Health & IBS | January 11, 2021

A young girl feeding her father a nutritious homemade sandwich.
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By now, most of us are aware that fibre plays a big role in how we poop. However, this doesn’t always translate to us getting enough fibre! We are busy people with busy lives, so thinking about fibre isn’t always at the top of our to-do list. That’s why today I want to discuss fibre and how to consume the best types of fibre for IBS in a practical way!

Sure, you’ve likely heard fibre helps you poop. But how? To put it quite simply, fibre plays three main roles in your digestive system:

  • Maintaining gut motility (how quickly things move through our gut)
  • Maintaining appropriate stool consistency
  • Feeding your gut bacteria – which helps with consistency, motility (and more!)

For help with navigating fibre with IBS our registered dietitians at Ignite Nutrition in Calgary, Alberta can help!

We need quite a bit of fibre each day. Women should aim for 25 grams per day and men 38 grams. Research shows that many North Americans struggle to hit these targets and generally only consume about 15 grams per day! Fibre comes from plant-based foods such as whole grains, vegetables, fruit, pulses, nuts, and seeds. These foods consist of two types of fibre, each of which contribute to digestion in a unique way.

What is Soluble Fibre?

This type of fibre dissolves in water and forms a gel. This action helps to absorb water in the bowel and subsequently helps to create soft, well-formed stool. Soluble fibre simultaneously helps to soften stool in constipation-dominant IBS and decreases diarrhea in those with IBS-D.

This type of fibre can also help to lower cholesterol levels and regulate blood sugars. A win for everyone!

Where to find soluble fibre:

  • oats
  • legumes
  • oranges
  • psyllium husk
  • chia seeds
  • flaxseeds
  • avocado

Insoluble Fibre

Unsurprisingly, insoluble fibre is the opposite of soluble fibre; it does not dissolve in water and therefore does not create a gel that helps bind stool. However, insoluble fibre is still very useful! It plays an important role in keeping digestion moving by increasing motility in the digestive tract and is therefore great for constipation.

Where to find insoluble fibre:

  • skins of fruit and vegetables
  • nuts & seeds
  • beans
  • whole grains
  • wheat bran

IBS & Fibre

Fibre is a very important aspect of managing irritable bowel syndrome.

Fibre can both improve and exacerbate symptoms, depending on specific fibre type and each individual’s tolerance levels.

Certain subtypes of dietary fibre called ‘fermentable fibres’ have been shown to help alter the gastrointestinal microbiota, leading to a potential increase in both quantity and variety of good gut bacteria and beneficial compounds. These dietary fibres are the food that our gut bacteria feed on, making them a crucial part of maintaining overall gut health. These kinds of fibres are referred to as prebiotics. Promoting a healthy gut microbiota is key in the prevention of diseases, energy and mood regulation, cardiovascular health, and much more.

That being said, some high fibre foods contain more FODMAPs (highly fermentable carbohydrates) than others. Highly fermentable fibres may worsen symptoms in some IBS patients, depending on their tolerance to specific FODMAPs. In fact, many of our prebiotic-rich foods contain FODMAPs in the form of galacto-oligosaccharides (GOS) and/or fructans. These types of carbohydrates are shown to contribute to increased gas production, bloating, and GI discomfort in many individuals with IBS.

Some examples of foods that contain GOS:

  • beans
  • cashews, pistachios, almonds
  • soybeans
  • green peas
  • beets

Foods high in fructans:

  • wheat
  • rye
  • barley
  • inulin & chicory root
  • onions
  • garlic

It is important to note that not everyone with IBS will need to avoid foods high in GOS and fructans.

Elimination is dependent on each person’s symptoms, and their unique IBS management plan. If you are just starting out on a low FODMAP diet, you will likely benefit most from avoiding these foods. However, if you have reintroduced FODMAPs and are tolerant to GOS and/or fructans, you can certainly liberalize your diet to include these foods. In fact, adding these foods back in tolerable amounts is very important for feeding those good gut bugs!

So, what happens if you are NOT tolerant to GOS and fructans?

Keep including small amounts, especially when your IBS symptoms are under control – for example, when you are less stressed – as stress can be a major trigger for IBS; it isn’t always food!

How to Get Enough Fibre During FODMAP Eliminations and Beyond

The elimination phase of the low FODMAP diet can certainly limit your access to dietary fibre, simply because of the narrowed number of foods to choose from. However, there are lots of fantastic low FODMAP foods that pack a BIG punch when it comes to fibre.

Some of my patients’ favourite sources of FODMAP-friendly fibres include:

  • bananas without brown spots
  • chia seeds
  • strawberries & raspberries
  • kiwi
  • peanuts, walnuts, hemp hearts, pumpkin seeds
  • oats
  • quinoa,
  • canned lentils and chickpeas

What fibre supplements should I take for IBS?

Although it is possible to get enough fibre from food alone, it can still be a struggle for some people! A fibre supplement is often a great option to help give that final push toward the recommended 25-38 grams.

Fibre supplements on the market are primarily made from soluble fibre; the type that creates a gel and helps to yield soft, bulky stools. However, the source of the fibre varies amongst products, making some more appropriate for IBS.

Psyllium Husk

Studies show this type of fibre provides symptom relief in both constipation and diarrhea predominant subtypes of IBS. It is often very well tolerated in IBS.


This type of fibre is high in fructans and therefore could potentially lead to more gas, bloating, and abdominal pain in those with irritable bowel syndrome. This is generally not recommended, especially during the elimination phase of the low FODMAP diet.

Partially Hydrolyzed Guar Gum

This type of fibre supplement is low FODMAP and has shown symptom relief in IBS patients – it is very slowly fermentable and seems to work very well in our IBS-D patients specifically.


This type of fibre is non-fermentable, therefore does not generally have side effects such as gas production, bloating, or pain. It may be especially useful for those with IBS-C as it helps to soften stool with its gel-forming properties.

As you can see, there is lots to consider with dietary fibre in irritable bowel syndrome – type, amount, and tolerance level. It may feel like your head is spinning! If you need help figuring out your fibre needs and which foods and/or supplements are appropriate for you, see one of our registered dietitians here at Ignite Nutrition – that specializes in IBS, physician, or pharmacist to learn more!

At the end of the day, fibre is considered a low-risk strategy in IBS management. It is non-systemic and easy to experiment with in a safe way in most cases. It may be just the thing you need to round out your IBS toolkit!

For help with navigating fibre with IBS our registered dietitians at Ignite Nutrition in Calgary, Alberta can help!

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