“Soluble fibre” versus “Insoluble fibre” is missing the “fermentable” point

“Fermentability” is a stronger indicator of dietary fibre health functionality than “solubility”.

If you are amongst those who take your gut health seriously, “dietary fibres” (DFs) and “prebiotics” are not scientific jargon for you. You already know that dietary fibres/prebiotics are substances from plant foods that escape digestion in your small intestine and upon reaching your colon they feed your gut microbiota. You might also know that feeding these billions of little creatures in your gut is a powerful way to achieve incredible health benefits.

But do you know that DFs can be of different types – soluble, insoluble, complex/whole-plant, isolated/purified, rapidly-fermenting, slowly-fermenting and non-fermenting – and all have specific roles to serve in your digestive health and overall well-being.

Do you know which one of these is optimal for you and what type is most benefiting for your health?

The most common way of classifying DF is based on their solubility in water. Soluble DF attracts water and forms a gel during digestion, thus slowing digestion. Insoluble DF does not dissolve in warm water. It adds bulk to our stools helping pass solids out more easily. However, this classification is being phased out in the nutrition community (1,2). This way of categorising DFs has limited links to health functionality and does not tell you much about their interaction with the gut microbiota that holds the power to unlock all the incredible health benefits from DFs.

Both soluble and insoluble fibres can be prebiotic & fermentable

Thus, nutrition and gut health experts believe that a more sophisticated way of classifying DFs for immediate relevance to physiological/health functions should be based on its fermentability (1). Fermentability refers to whether the bacteria in our colon/large intestine can ferment or degrade the DF into metabolites – like the anti-inflammatory Short-Chain Fatty Acids (SCFAs) and gas. SCFAs are incredibly powerful health elixir whose effects extend beyond the gut to regulate an array of health functions including metabolic and immune activities throughout the body.

Generally, soluble DFs are assumed to be rapidly fermentable than insoluble fibres. Although, this perception is changing with scientific evidence emerging to support fermentability of insoluble fibres in the gut  (1,3). What consumers must appreciate is that the rate and the site of the fermentation of DFs in our gastrointestinal tract is a critical factor. Certain DFs, specially the purified/isolated fibre extracts are rapidly broken down in the terminal part of small intestine instead of in your colon and may often be associated with undesirable gastrointestinal symptoms including bloating, abdominal pain and flatulence. This particularly holds value for those who suffer from food sensitivities, indigestion, bloating/abdominal symptoms owing to chronic health conditions like IBS, IBD or acid reflux for instance. Also, the SCFAs produced are sometimes insufficient to be distributed to the distal parts of the colon, the greatest organic site for such inflammatory diseases.

Alternatively, whole-plant fibres as they occur in nature (in plant cell walls of fruits, vegetables, nuts, whole-grains and grasses etc.) are more biochemically complex with the appropriate ratios of soluble : insoluble and slow-fermenting : fast-fermenting fibre fractions (3). Such complexity allows them to be first broken down in the colon by the right bugs into large a number of simpler by-products that can be further utilised to feed other gut microbial members thus, promoting microbial diversity. This encourages fermentation to occur and SCFAs to be produced at a uniform rate and distribution throughout the entire colon length thus nourishing the whole colon (4,5).

Uniform fermentation is key to lower gas & bloat maintenance

Be a smart consumer and choose DF supplements like Kfibre, a whole-plant complex DF prepared to closely represent the plant fibres to harness the maximum benefits for your gut health and overall well-being. It is prepared from whole virgin sugarcane (sucrose removed) with minimum processing to preserve not only the DFs in their most natural forms, but to also retain the inherent micronutrients and antioxidant phytonutrients for added health benefits.

Research from Australian universities has confirmed its excellent potential in conferring anti-inflammatory effects in the gut through increased production of SCFAs and promoting microbial diversity owing to its ability to be uniformly fermented throughout the colon length.

Join so many others in enjoying good digestive health and overall well-being with the uniform fermentation benefits of Kfibre in your diet!

By Dr Tanvi Shinde, PhD