Should I take a fibre supplement?

What is fibre?

Dietary fibre is a component of plant foods that is not fully digested by our bodies. High fibre intakes in the diet lead to multiple health benefits including reduced constipation, decreased risk of developing type 2 diabetes, heart disease and colorectal cancer. In fact, the healthiest diets always include dietary fibre. Overall there are multiple types of dietary fibres which can be classified by their characteristics which include solubility, fermentability and viscosity. 

The nature of each type of dietary fibre determines the specific role they play in the body. 

Moreover, fibre is often categorised as either soluble or insoluble, however there are other physiochemical characteristics of fibre that we need to consider in order to understand the full spectrum of dietary fibre. 

Fermentability of fibre

Fermentability is one of three essential properties to characterise fibre. In addition, the other two are solubility and viscosity. Fermentability is a scientific term to describe the process which occurs when fibre is broken down by the bacteria in our gut. 

Fermentation takes place in our large intestine, where our gut bacteria essentially “eats” fibre and as a result, produces short-chain fatty acids and gases as by-products of the fermentation process. 

If you think about how alcoholic beverages such as wine and beer are made, it involves a similar process. Put simply, alcoholic fermentation occurs when yeast uses sugar as fuel to produce ethanol, carbon dioxide and other byproducts. In fact, sugar is the fuel for yeast much like fibre is the fuel for our gut bacteria.   

Viscosity of fibre

Dietary fibre can also be categorised based on its viscosity. Viscous fibres develop a thicker consistency when mixed with liquids. Examples of viscous fibres include psyllium, beta-glucans (found in oats, barley and fungi) and pectins (found in fruit, vegetables and legumes). When we eat viscous fibres, they form a gel like substance in our gut, this can decrease the absorption rate of certain nutrients such as glucose. 

Moreover, other fibres such as cellulose (found in cell walls of green plants) and resistant starch (found in cooked and cooled starchy foods such as potatoes are non-viscous. Cellulose is also an insoluble fibre and resistant starch has very low solubility in water. However, these types of fibres play a different role in the body from viscous fibres. In fact, they add bulk to our stool and help keep our bowel movements regular. (1)(2)

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