Fibre and IBS: Understanding Which Types to Include and Avoid?

Fibre and IBS: Understanding Which Types to Include and Avoid?

The Tummy Clinic | March 9th, 2022

The truth about fibre and IBS

It is important to choose gut-friendly fibre options to avoid worsening of IBS symptoms, writes Nichola Marie

While fibre-rich food is thought to be good for gut bacteria and to improve health, its relation with Irritable Bowel Syndrome (IBS) is not as uncomplicated. Fibre is beneficial to most people with IBS; however, not all fibre sources are suitable. Fibre can lead to increase in frequency or urgency of bowel movements in those with IBS-D (diarrhoea). It is also known to make those with IBS-C (Constipation) feel worse.

A high fibre diet (with a catch) is recommended as nutrition therapy for IBS, owing to the popularity of the low FODMAP diet. FODMAP stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols, which are short-chain carbohydrates and sugar alcohols that are poorly absorbed by the body, and can result in abdominal pain and bloating in those with IBS. However, a high fibre diet, broadly prescribed, can also lead to bloating, gas, and abdominal pain.

Facts about fibre

Fibre is the largely indigestible part of food that helps in elimination of waste from the large intestine. An important nutrient to maintain overall health, it provides benefits to health conditions such as cardiovascular disease, cancer, diabetes, weight management, and IBS—when selected correctly. Many sources of fibre encourage the growth of good gut bacteria and lead to a healthier gut microbiome.

Fibre comes in soluble and insoluble types. The variety of soluble fibre dissolves in water, draws water into the stool, and forms a gel like substance which helps move contents down the gastrointestinal track. These soluble fibres are found in foods such as oats, strawberries, citrus fruit, rice, potatoes, beans, broccoli, and carrots.

Warning: Prebiotic soluble fibres such as inulin and fructooligosacchharides (FOS) are highly fermentable and can trigger IBS symptoms. While inulin and FOS occurs naturally in asparagus, chicory root, garlic, onions, and artichoke, they are also often added to yogurts, probiotic supplements, and fibre supplements.

Insoluble fibres

on the other hand, are large and coarse, and add roughage to bulk to stools. They pass through the gastrointestinal tract unchanged, and help regulate bowel movements by irritating the lining of the large intestine and bringing about a bowel movement. It can quicken gut transit time and thus be helpful for those with IBS-C; however, it could be disadvantageous for those with IBS-D. Wheat bran, nuts, seed hulls, kale, blackberries, cauliflower and fruit skins are sources of insoluble fibre.

Embarking on a low FODMAP diet?

It is important not to compromise on fibre intake when adopting a low FODMAP diet, as it can have a negative impact on beneficial gut bacteria and IBS symptoms. Choose low FODMAP fibre rich foods to reach the daily recommended intake of 25-38 grams of fibre per day for adults.

Here’s looking at how fibre helps those with different IBS conditions…


Fibre helps to achieve regular bowels. Before starting on the low FODMAP diet, strive to hit your fibre goals through whole foods and possibly supplements. Gas and bloating could still be experienced due to inadequate elimination. In case of slow gut transit time and constipation, back up bloating can occur. Make sure you have an effective bowel regimen in place to ensure laxation when you increase your fibre intake. It could require changes such as postural changes, or osmotic laxatives and magnesium salts recommended by your IBS specialist.


A misconception exists that fibre is harmful for those with IBS-D, as it results in frequent bowels. However, the fact is that fiber—and soluble fibre in particular—can help bulk up and bind stools, thus proving highly beneficial to those suffering from diarrhoea. Increase soluble fibres such as oats, beans, flaxseeds, chia seeds, and low FODMAP fruits and vegetables to boost this beneficial fibre. Alongside, ensure you drink sufficient water. Constipation is known to increase if water intake is low, besides which extra fibre intake needs additional water for digestion.

Eat up!

Here’s a glance at the fibre content of some high fibre, low FODMAP foods…

  • 1-ounce (30 g) pumpkin seeds = 5.2 grams fibre
  • 1 tablespoon Chia seeds = 4.1 grams fibre
  • 1 tablespoon Flax seeds = 2.9 grams fibre
  • 1 medium sweet potato baked in skin = 3.8 grams fibre
  • 1 medium baked potato in skin = 3.6 grams fibre
  • 3 cups (55 g) air popped popcorn = 3.5 grams fibre
  • 1 medium orange = 3.1 grams fibre
  • 1-ounce (30 g) nuts = ~3 grams fibre
  • ½ cup (78 g) cooked quinoa = 2.6 grams fibre
  • ½ cup (84 g) canned and drained chickpeas = 8.1 grams fibre
  • ½ cup (90 g) cooked black beans = 7.5 grams fibre
  • ½ cup (52 g) raw oats = 4 grams fibre
  • 1 cup (150 g) strawberries = 2.9 grams fibre
  • 1 cup (125 g) chopped carrot = 3.6 grams fibre

Fibre Supplements

It is advisable to have your dietician or health care provider decide on one that is right for you. Some popular fibre It is advisable to have your dietician or health care provider decide on one that is right for you. Some popular fibre supplements include Psyllium Husk Fibre, Partially Hydrogenated Guar Gum, Acacia Fibre, Methylcellulose, Calcium Polycarbofill, and Wheat Dextrin. The list of fibre supplements to avoid includes Inulin, Wheat Bran, and Polydextrose. It is important to consult a registered dietitian for diet plans and fibre supplements.


Frequently Asked Questions

Irritable bowel syndrome (IBS) is characterized by a variety of symptoms, including cramping, abdominal pain, bloating, gas, and diarrhea or constipation, or both. IBS is a chronic condition that you’ll need to manage long term. The cause is not well understood.

There is no definitive test to diagnose IBS. IBS is diagnosed after your doctor has reviewed your symptoms and occasionally ordered tests to rule out other conditions.

Visits at the Tummy Clinic are not covered by OHIP or your provincial health care system, however, most extended healthcare plans cover many aspects of the care you will receive here, such as visits to Naturopathic Doctors, Dietitians, Social Workers or Psychotherapists. Check your benefits package or contact your insurance company for more information.