For gut health enthusiasts the term “Prebiotic dietary fibre” is not jargon.
Many different kinds of prebiotic dietary fibre supplements are available in your local pharmacy. Your supermarket’s “health aisle” displays range of different food products that tout the benefits of added prebiotic fibres with claims to resolve all your digestive issues and support healthy gut bacteria. But do you know that not all prebiotics are created equal? Do you know that many soluble prebiotic fibres that are commonly available in the market today are purified & isolated ingredients which have been extracted from plants?
Limitations of isolated or extracted prebiotics
You may ask, why does it matter if a prebiotic fibre is isolated and extracted form of dietary fibre. Well, below are 4 major limitations of purified/ isolated prebiotic fibres extracted from plants.
1. Limited biochemical complexity:
Relative to those from the whole plant foods like fruits and vegetables, isolated and purified prebiotic fibres present limited biochemical complexity (Source). They are usually stripped of bioactives and phytonutrients (with several additional benefits) that the plant source would inherently provide. The consumption of the complex mixture of phytochemicals in whole fruits and vegetables is likely to be of greater benefit than the single phytochemicals in isolation (Source).
2. Rapid fermentation and digestive symptoms:
Purified soluble oligosaccharides have become very popular as potential prebiotics partly because they do not alter the viscosity or texture of foods due to their low molecular weight, and because they are usually highly fermentable (Source).
However, such soluble isolated dietary fibres tend to ferment rapidly in the terminal iluem (the part of small intestine) and proximal region of the colon (large intestine) producing excessive gas. Excess gas production causes the intestines to expand causing the intestinal walls to stretch thus producing the undesirable symptoms including bloating, flatulence and abdominal cramps. This is an issue particularly in people with sensitive gut including those with IBS (irritable bowel syndrome). A person taking extracted prebiotics intending to get relief from digestive issue might experience additional or slightly severe digestive symptoms due to rapid fermentation at the wrong site in the gut when taking prebiotic extracts. Hence, it is to be recommended that whole-plant complex prebiotic fibres – one that is prepared to retain the biochemical complexity of plant cell walls, that are able to slowly & uniformly ferment along the colon, be fed to reduce the likeliness of undesirable gastric symptoms.
A study by Monash University confirmed that supplementing a slow-fermenting sugarcane fibre, alongside a low FODMAP diet to be effective in providing improvement in both IBS type symptoms and stool satisfaction in patients with IBS (Source).
3. Selective gut bacterial enrichment:
Some isolated dietary fibres are known to only support the selective population of certain bacteria e.g., Bifidobacteria. While Bifidobacteria are beneficial bacteria and common as probiotics, it is important to point out that improving the overall gut microbial diversity rather than targeting specific species is regarded as the most effective means of acquiring the health benefits.
This is because a number of microbial species are interdependent on each other for fermentation of fibres to short-chain fatty acids (SCFAs). Bifidobacterium bacteria for instance are efficient primary degraders of certain soluble fibres to produce intermediate products (like acetate, lactate, mono/oligosaccharides), which are then utilised by other bacteria (like the Eubacterium rectale and Faecalibacterium prausnitzii) then produce the butyrate (Source). Others like the Akkermansia species (one of the next-generation beneficial gut microbes) are major producers of propionate (Source). Therefore, supporting the microbial diversity is critical to promote sufficient levels of different SCFAs and other beneficial microbial metabolites.
4. Limited or no hind gut stimulation:
Since these extracted products undergo processing for purification and isolation, soluble prebiotics are so readily fermentable that they may be completely utilised by the end of the terminal ileum (Source). Thus, SCFAs produced may not be sufficient to provide the nourishment to the distal region of the colon. Demonstrating the critical relevance, studies in humans and animals confirm that the distal colon is the site of greatest organic disease with significant inflammation and altered microbial diversity. It is clear that the delivery of butyrate to this part of the colon may be especially important.
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 (Source). It is therefore more practical that isolated soluble prebiotics be fed in conjunction with more slowly fermentable or uniformly fermentable dietary fibres, which can allow prebiotic fermentation to continue at a whole length in the large intestine (source).
It is also important to acknowledge that specific soluble, isolated, or extracted fibres may have important roles in precision application in specific areas of health – such as where the major focus of prebiotic application is to modulate specific group of gut bacterial members or a particular type of microbial metabolite. While the research efforts are underway (with its own sets of challenges) for precision application of certain isolated dietary fibres in very specific health issues, whole-plant complex prebiotic fibres hold the prime position when it comes to supporting the maintenance of overall gut health and wellbeing.
Australian Virgin Sugarcane Prebiotic
If you are wondering where you can get whole-plant complex prebiotic fibre, you are in luck as its available right here in Australia from locally grown plant source – sugarcane.
Health Food Symmetry’s Kfibre® – Virgin Sugarcane Prebiotic is a whole-plant complex prebiotic dietary fibre made from virgin sugarcane (with most sucrose removed) for gut health management and microbiome support containing bioactive phytonutrients & antioxidants.
Kfibre is prepared by chemical-free process (using only water) to remove sugar and such preparation preserves the cell wall components and results in a high 87% content of total dietary fibre with prebiotic benefits. Such fibre contains both insoluble and soluble prebiotic fermentation benefits in addition to retaining inherent micronutrients and antioxidant phytonutrients for added health benefits. Kfibre is gluten-free & Monash University Low FODMAP certified, making it suitable also for those with sensitive gut.
Due to the retention of biochemical complexity, phytonutrients and the intact insoluble and soluble fibre fractions the sugarcane fibre has been shown to ferment at a more uniform rate (Source) through the entire colon length nourishing the proximal and importantly the distal colon (Source).
Scientific research has confirmed the excellent potential of this fibre in areas such as colonic inflammation, gut barrier integrity, influence the microbial diversity and boost the levels of SCFAs along the entire colon length (Source) (Source). In these studies, the anti-inflammatory benefits boosted even further when Kfibre was paired with a fibre-digesting probiotic bacterium as synbiotic. In addition, in a pilot human clinical study, 3-week consumption of Kfibre showed marked reduction in digestive symptoms (heartburn, acid regurgitation, and total symptoms scores) in first time sufferers reporting heartburn (Source).
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 prebiotic dietary fibres and occur in conjunction with range of micronutrients and phytonutrients with added health benefits. But when we use processing methods – heat, chemicals etc to isolate, extract and/or purify only a specific type of the fibre portion, we not only loose the range of phytonutrients that are inherently present but also compromise the cell wall complexity of how the fibres occur in nature.
A thought worth pondering on – are isolated soluble fibres the new ultra-processed food additives?
By: Dr Tanvi Shinde (PhD) & Kent Taylor