Soluble Fibre and Insoluble Fibre

dietary fibre from wholegrans

Wholegrains, nuts and seeds are well-known as sources of all-important dietary fibre. Do you need soluble fibre? Or insoluble fibre? Can you get your dietary fibre from other sources? Read on to find out.

Soluble Fibre. Insoluble Fibre. What is the Difference? How Do they Aid Gut Health?


Dietary fibre is a critical component of a healthy diet, with numerous known benefits in supporting gut health. Fibre can be broadly categorised into two types: soluble and insoluble. Each has unique characteristics and contributes to digestive well-being. In this article, we will explore the differences between these two types of fibre and how they aid gut health.

Soluble Fibre

Soluble fibre, as the name suggests, dissolves in water, forming a gel-like substance. It is found in various plant foods, including oats, beans, various fruits, and a wide range of vegetables. Soluble fibre confers several positive benefits that aid gut health:

Prebiotic Properties: Soluble fibre functions as a prebiotic. This means it can provide nourishment for beneficial gut microbes, including probiotic bacteria. These bacteria can ferment soluble fibre in the large intestine, producing compounds called short-chain fatty acids (SCFAs), for example butyrate, acetate, and propionate. SCFAs are essential for maintaining gut health, as they provide energy for the cells of the intestines, aid in ensuring integrity of the intestinal lining, and have anti-inflammatory properties.

Improved Bowel Regularity: Soluble fibre absorbs water in the digestive tract, forming a gel, which adds bulk to the stool. This gel-forming property aids in regulating bowel movements, preventing both constipation and diarrhoea. Thus, soluble fibre can be particularly beneficial for individuals with irritable bowel syndrome (IBS).

Lowering Cholesterol Levels: Some soluble fibres, like beta-glucans found in oats and in a range of medicinal mushrooms, have been shown to help lower LDL cholesterol (the “bad” cholesterol). This may help reduce the risk of heart disease in susceptible individuals.

Regulate Blood Sugar Levels: Soluble fibre can slow down the absorption of sugars from the digestive tract into the blood stream, thus helping to modulate blood sugar levels. This is particularly important for those with diabetes or pre-diabetes, or those at risk of developing the condition.

Apple pectin, soluble fibre

Apples are an excellent source of apple pectin, a soluble fibre.

Insoluble Fibre

Like soluble fibre, insoluble fibre cannot be digested by humans. But unlike soluble fibre, the insoluble type does not dissolve in water. Instead, it remains relatively intact as it moves through the digestive system.

Common sources of insoluble fibre include wheat bran, whole grains, nuts, and certain vegetables, such as corn. Insoluble fibre also plays a crucial role in supporting gut health. Here’s how:

Promotes Regularity: Insoluble fibre adds bulk to stool, which can help prevent and alleviate constipation. It can speed up transit time through the digestive tract, reducing the risk of a back-up of faecal material in the intestines.

Colon Health: Consumption of insoluble fibre has been linked to a reduced risk of colorectal cancer. This is thought to be because it encourages regular bowel movements, thus reducing the amount of time the intestinal lining is exposed to potentially harmful substances.

Weight Management: Including good amounts of insoluble fibre in the diet contributes to a feeling of fullness and satiety. This helps control appetite and can aid in weight management by reducing overall calorie intake.

Colonic Cleansing: Insoluble fibre can be thought of as a gentle scouring pad. acting as a natural colon cleanser, facilitating the removal of waste and toxins from the body.

Corn insoluble fibre

Balancing Soluble and Insoluble Fibre

For optimal gut health, it’s essential to include a variety of foods rich in both soluble and insoluble fibre in your diet. This balance ensures comprehensive digestive support, from regular bowel movements to a thriving gut microbiome.

Remember to drink plenty of water when increasing your fibre intake, as adequate hydration is necessary for the effective function of both soluble and insoluble fibre.


Both soluble and insoluble fibre have unique and vital roles in promoting gut health. Incorporating a diverse range of fibre-rich foods into your diet can help you reap the full spectrum of benefits, supporting a healthy digestive system and overall well-being.

If you are one of many people who cannot tolerate fibre or avoid it due to fear of increased digestive distress, please, make an appointment with one of the team at the Auckland Gut Clinic. Avoiding a health-giving substance because of gut problems is not the solution – getting your gut (and microbial balance) right is!

How Much Dietary Fibre Do I Need?

The optimal intake of fibre from diet varies depending on a range of factors. These include age, gender, and specific health concerns, which influences individual needs. However, a general guideline for adults is to aim for 25 to 30 grams of fibre daily. It’s essential to include a variety of different fibre sources, such as fruits, vegetables, whole grains, legumes, and nuts, in your diet for overall well-being and to ensure you get good amounts of the different types of fibre. Consulting with a healthcare provider or nutritionist can provide personalised recommendations based on your specific health goals and needs.

Use this handy table to help you achieve a daily intake of 25-30 grams of dietary fibre.  Use supplemental fibres (see the bottom of the table) to top up what’s missing from your diet. Easy-peasy!

Your health (your digestion & your gut microbes) will be better off!


Food Fibre Content (in grams)
1 cup of lentils (cooked) 15 grams
1 cup of black beans (cooked) 15 grams
1 cup of broccoli 5 grams
1 cup of quinoa (cooked) 5 grams
1/4 medium avocado 2.5 grams
1 medium pear 6 grams
1 medium apple 4 grams
80 g raspberries (1 serve) 6 grams
1 cup of whole wheat pasta 6 grams
2 slices of whole wheat bread 4 grams
15 g (~10) almonds 2 grams
1 cup of oatmeal (cooked) 4 grams
1 cup of brown rice (cooked) 3.5 grams
1 medium carrot 2 grams
1 cup of spinach 4 grams
1 tblsp Acacia fibre 7 grams
1 tblsp Apple pectin powder 9 grams
1 tblsp Flaxmeal (flaxseed powder) 8 grams
1 tblsp Larch powder 4.5 grams
7 g PHGG powder 6 grams



  1. Barber TM, et al. The Health Benefits of Dietary Fibre. Nutrients. 2020 Oct 21;12(10):3209. doi: 10.3390/nu12103209.  PMCID: PMC7589116..
  2. Dahl, W. J., & Stewart, M. L. (2015). Position of the Academy of Nutrition and Dietetics: Health Implications of Dietary Fibre. Journal of the Academy of Nutrition and Dietetics, 115(11), 1861–1870.
  3. McRorie, J. W. (2015). Evidence-Based Approach to Fibre Supplements and Clinically Meaningful Health Benefits, Part 1: What to Look for and How to Recommend an Effective Fibre Therapy. Nutrition Today, 50(2), 82–89. PMID 25792618
  4. Slavin, J. (2013). Fibre and Prebiotics: Mechanisms and Health Benefits. Nutrients, 5(4), 1417–1435. DOI: 10.3390/nu5041417



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