top of page

What type of fibre lowers blood sugar? Viscous soluble fibre and diabetes.

You’ve probably already heard at some point that fibre is an important part of a healthy diet. If the mention of fibre has you thinking “yeah yeah, my bowels are moving just fine”, keep reading because today we are zeroing in on viscous soluble fibre and how it helps to support blood sugar management.

Viscous soluble fibre and blood sugar - Beyond Diabetes Nutrition | Lucy Zhang - Registered Dietitian

What is viscous soluble fibre?

Viscous soluble fibre are gel-forming fibre. They dissolve in water to form a thick gel-like consistency. Like other dietary fibres, viscous soluble fibre are non-digestible carbohydrates. This means that they are not broken down by our digestive enzymes and do not raise blood sugar.

What is viscous soluble fibre - Beyond Diabetes Nutrition | Lucy Zhang - Registered Dietitian

How does viscous soluble fibre improve blood sugar?

Viscous soluble fibre increases the viscosity of chyme (the mixture of gastric juices and partially digested food that leaves our stomach and enters the small intestine), making it thicker in consistency and slower to flow through the digestive tract. This slows the ability of digestive enzymes to interact with the nutrients, thus slowing the absorption of glucose in the small intestine.

This slowing down of nutrient breakdown and absorption means that some nutrients will reach the ileum (the last section of our small intestine) before being absorbed. This stimulates the release of GLP-1 (glucagon-like peptide 1) - a hormone that acts to decrease appetite, increase insulin production and increase insulin sensitivity.

Nutrients reaching our ileum also triggers another mechanism called the ileal brake - which tells our body to slow down the emptying of the stomach and slow down the movement of food through the small intestine to allow for optimal digestion and nutrient absorption. Again, slower movement through our digestive tract means a gentler rise in blood sugar.

How viscous soluble fibre improves blood sugar - Beyond Diabetes Nutrition | Lucy Zhang - Registered Dietitian

How much viscous soluble fibre do I need?

For adults with diabetes, Diabetes Canada recommends 30 to 50 g per day of dietary fibre, with a third or more (10 to 20 g/day) coming from viscous soluble fibre to support blood sugar management.

What are good sources of viscous soluble fibre?

  • Oats

  • Barley

  • Apples, pears

  • Psyllium

  • Ground flaxseed

  • Chia seeds

Food sources of viscous soluble fibre - Beyond Diabetes Nutrition | Lucy Zhang - Registered Dietitian

How to eat more viscous soluble fibre?

  • Make oatmeal part of your regular breakfast rotation

  • Add ground flaxseed or chia seeds to hot and cold cereal, yogurt, and smoothies

  • Sprinkle ground flaxseed when having toast with nut butter

  • When cooking rice, replace half with barley

  • Make fruit jam with chia seeds or psyllium powder


Fiber. Oregon State University. Accessed Feb 2, 2023.

McRorie JW, McKeown NM. Understanding the Physics of Functional Fibres in the Gastrointestinal Tract: An Evidence-Based Approach to Resolving Enduring Misconceptions about Insoluble and Soluble Fiber. J Acad Nutr Diet. 2016; 117(2):251-264.

Sievenpiper JL, Chan CB, Dworatzek PD, et al. Diabetes Canada 2018 Clinical Practice Guidelines for the Prevention and Management of Diabetes in Canada: Nutrition Therapy. Can J Diabetes. 2018; 42:S64-S79.


Recent Posts

See All


bottom of page