Relationship between Livaux consumption, butyrate and health effects

Within our gut microbiome are key bacteria which have been found to be very important for our health. One in particular is our friend, Faecalibacterium prausnitzii, affectionately known as F. prau.

F.prau is one of the most abundant bacteria in the healthy human intestine, accounting for up to 15% of the total faecal microbiota.

One of the key reasons we love F. prau is that it is a major butyrate producer. Butyrate is a short-chain fatty acid (SCFA) which plays a major role in gut physiology and our health. One of its most important functions is to provide energy to the colon cells.

Colon cells use a different energy source compared to other human cells

The cells lining the surface of our colon, the colonic epithelium, are called colonocytes. The colonic epithelium performs two key functions: absorbing nutrients and other useful substances and preventing access to harmful substances.

All of the cells in our body require energy to function and grow. Most of our cells will generate their energy by utilising glucose (sugar) or ketone bodies. Colonocytes, however, use butyrate as their primary energy source.

Butyrate is produced by specialised bacteria in the gut, like F. prau that ferment (feed upon) dietary fibre. Most of the butyrate-producing bacteria are found at the start of the colon (proximal), closest to the small intestine, so concentrations of butyrate here are high. This butyrate travels through the rest of the colon towards the distal end, feeding colonocytes throughout.

The colonocytes metabolise butyrate in their mitochondria: specialised organelles (mini organs) which are the powerhouses of our cells. When enough butyrate is available, colonocytes use the butyrate to support proliferation (growth) and differentiation (change of cell type).

Some of the cells grow into specialised epithelial cells called goblet cells, named for their shape. These goblet cells make mucin, the main structural component of the mucus which lines our intestines. The gut mucus layer is our first line of defence against pathogens, toxins and other foreign particles. Without themucus, the contents of the lumen, including the trillions of microbes that live there, can come into contact with the colonocytes and potentially cause us harm.

Healthy colon cell renewal reduces the risk of the formation of polyps

When there is more than enough butyrate for the cells, the excess butyrate accumulates in the cell nucleus and leads to the cells undergoing a form of programmed cell death called apoptosis. The cells then exfoliate off into the mucus layer in the lumen of the colon and are swept away downstream. Overall, the epithelia of the colon is completely replenished by this process with a turnover rate of around 4-6 days. This programmed cell death and replenishment helps prevent genetic mutations from accumulating, which can lead to the formation of polyps and cancerous tumours if left unchecked.

In the absence of butyrate colonocytes undergo autophagy, the process of breaking down their own proteins for energy. Studies have shown that germ-free mice – those born in a sterile environment without any bacteria at all, even gut bacteria – have poorly developed colons, with colonocytes fuelled only by autophagy. Feeding them tributyrin, a dietary form of butyrate, restores their colonocytes. Adding a butyrate-producing bacterium and the dietary fibre these bacteria need to make butyrate also restores the colonocytes.

Energise your gut with Livaux

As you can see, it is really important to ensure we have enough butyrate being produced so our colons remain healthy, energised and protected. The best way to do this is to feed our butyrate-producing bacteria, like F. prau, with dietary fibre. F. prau in particular likes to feed on high methoxy pectin, such as that found in Livaux®, a gold kiwifruit powder, which has been shown in clinical studies to increase the relative abundance of F. prau.

The other great thing about the pectin in Livaux, is that due to its complex structure, it is slowly fermented along the whole length of the colon. The colon is a long tube, where undigested food mixed with water enters the proximal end and is fermented by the gut microbiota before the remnants are excreted from the distal end. Because the pectin takes longer to ferment, it can hold more water and continue to have bacteria associated with it as it transits the colon.

This additional bulk stimulates gut motility and therefore faster transit of proximal colonic bacteria, like F. prau, and their butyrate towards the distal colon. Therefore, fermentation continues to occur right throughout the colon, with butyrate being produced to prevent autophagy in colonocytes and promote normal colonocyte turnover through proliferation and apoptosis.

F.prau and COVID are linked in a number of ways

As we noted in our earlier blog on the gut microbiome and COVID infection, dysbiosis of the gut microbiome, including reduced numbers of Faecalibacterium prausnitzii (F. prau), has been observed in patients with COVID-19. In particular, reduced levels of F. prau was associated with increased duration and severity of COVID-19 infection symptoms (Yeoh et al., 2021). 

It is well-known that F. prau, as an important beneficial gut bacterium, has anti-inflammatory properties and affects the immune system, but how is it linked to COVID and why might those who suffer more and for longer from COVID-19 have lower levels of F. prau? 

Several mechanisms have been proposed to explain how F. prau contributes to immunity. These are: 

• enhancing the gut barrier – part of that critical first line of defence against invaders;  
• directly inducing anti-inflammatory cytokine secretion;  
• directly inhibiting the secretion of pro-inflammatory cytokines; and,  
• producing anti-inflammatory/immunomodulatory metabolites (He, Zhao, & Li, 2021).  

Anti-inflammatory and immunomodulatory effects of F. Prau 

One of the most severe symptoms/pathologies of COVID-19 is cytokine storm, characterised by huge increases in the levels of pro-inflammatory cytokines such as IL-6, INF-γ, and TNFα.

 This hyper-inflammation is associated with poor disease outcomes for COVID-19 infected patients and is presently treated with immunosuppressant medication such as the corticosteroid dexamethasone (K et al., 2021).  It has been proposed that commensal (friendly) bacteria with anti-inflammatory and immunomodulatory capabilities, such as F. prau, could potentially down-regulate the cytokine response, to decrease the harmful effects of inflammation while maintaining a positive immune response (Baindara et al., 2021). Therefore, high levels of F. prau may contribute to a reduced cytokine storm.

F. prau can decrease pro-inflammatory cytokine secretion and increase anti-inflammatory cytokines. For example, studies have shown that F. prau exposure significantly decreased pro-inflammatory cytokines, IL-6, IL-12 and TNFα, increased anti-inflammatory IL-10, and enhanced immune cell response upon exposure to a known antigen (a foreign substance that induces an immune response) (Sokol et al., 2008; Rabiei et al., 2019; Rossi et al., 2016).

F. prau is a major producer of butyrate and salicylic acid, two bacterial metabolites that have known anti-inflammatory properties.

It has been suggested that butyrate could function as a possible replacement for dexamethasone to treat the hyper-inflammation associated with COVID-19 due to its anti-inflammatory activity (K et al., 2021). Both butyrate and salicylic acid can inhibit inflammation (Ferreira-Halder, de Sousa Faria & Andrade. 2017; Elce et al., 2017; Cholan et al., 2020; Zeng et al., 2017; Kabel, Omar & Abd Elmaaboud, 2016).

Gut barrier integrity  

It is thought that disruptions in gut barrier integrity may contribute to the gastrointestinal symptoms associated with COVID-19. Kim (2021) proposes that a ‘leaky gut’, driven in part by dysbiosis, could allow the virus to leave the GI tract and enter the bloodstream. This could then lead to an increase in inflammation, and allow the virus access to other ACE2-expressing cells throughout the body such as in the heart, brain, and liver (Kim, 2021).

This would then trigger other COVID-19 symptoms such as headache, hepatic, and cardiac dysfunction (Kim, 2021). F. prau may be able to prevent this, through its ability to improve gut barrier integrity. For example, in a mouse model of low-grade inflammation in the gut, F. prau treatment significantly decreased intestinal permeability (Martín et al., 2015). F. prau treatment was also shown to increase the expression proteins which are part of the junctions between cells in the mouse colon, and this effect was associated with a decrease in inflammation (Laval et al., 2015).  

The elderly and those with underlying health conditions, including hypertension, diabetes and obesity, are more susceptible to COVID-19 infections. These populations often have disrupted gut barrier integrity (leaky gut) and dysbiosis (including low F. prau) which may be a crucial pathway that allows the COVID-19 virus to gain access to ACE2 receptors on enterocytes and leak out of the GI tract to spread throughout the body (see figure).

Once into the bloodstream, this may cause further inflammation exacerbating the leaking gut. In contrast, those with a healthy digestive tract, including good barrier integrity and a good level of butyrate-producing gut bacteria, such as F. prau, will have a higher number of immune cells. This may enable the immune system to contain the virus in the GI tract and it will subsequently pass out the back end.  

Alternatively, it has also been proposed that gut dysbiosis may result from the COVID-19 infection. Cytokines secreted during the “storm” reach the gut via the blood and/or the virus travels to the gut, leading to local inflammation, a leaky gut and dysbiosis.   

Either way, treating the dysbiosis in the gut by supplementation with probiotics and/or prebiotics may rectify the issue allowing the body’s defences to eliminate the virus (Conte & Toraldo, 2020). In particular, those prebiotics or probiotics which can increase F. prau, such as Livaux® gold kiwifruit powder, may help to bring balance back to the gut, reduce inflammation and support the body’s natural immune system to fight off the virus.  

Low levels of F. prau linked to more severe COVID infection

Livaux® prebiotic powder, from New Zealand gold kiwifruit, has been clinically shown to increase Faecalibacterium prausnitzii (F. prau) numbers in individuals with low F. prau levels (1). Research show that low levels of F. prau are associated with increased SARS-CoV-2 (Covid-19) virus symptom severity and duration. This finding is covered in a recent NutraIngredients article (2). 

Covid-19 invades cells by a process starting with binding the ACE2 receptor (3). This receptor is found in highest levels on the surfaces of cells of the lungs, and on the surfaces of the cells lining the intestines (4). In the intestines, ACE2 is linked to inflammation and the gut microbiome (5). Covid-19 is known to cause gastrointestinal disturbances, with high incidence of diarrhoea and microbiome dysbiosis (3-9). Viral material has been detected in faeces, even after the respiratory tract tests negative, illustrating the risk of faecal-oral transmission (3) and an urgent need to address these gastrointestinal issues (10). 

In order for the Covid-19 virus to invade intestinal epithelial cells, it must survive transit through the stomach acid. Indeed, individuals on proton pump inhibitors (which reduce stomach acidity) are at risk of increased Covid-19 symptom severity and duration (11-13). Similarly, susceptibility to the virus is age-related (14), and increased age is associated with decreased stomach acidity (4), as well as decreased overall immune function and microbial dysbiosis (15). 

The microbial dysbiosis associated with Covid-19 is well documented, and the bacteria most commonly inversely correlating with presence or severity of Covid-19 symptoms is F. prau.  

For example, recently patients with Covid-19 were shown to have significantly underrepresented F. prau, Eubacterium rectale and Bifidobacterium adolescentis, with the strongest inverse correlations with severity being numbers of F. prau and Bifidobacterium bifidum (16).  

A previous study showed Covid-19 patients had lower numbers of Eubacterium rectale, Ruminococcus obeum, Lachnospiraceae bacterium 1_1_57FAA and F. prau (17). Again, F. prau most strongly negatively correlated with severity, in addition to Alistipes (17). These patients were also shown to have greater numbers of opportunistic pathogens known to cause bacteraemia such as Clostridium hathewayi, Actinomyces viscosus, Bacteroides nordii, and Coprococcus species known to upregulate ACE2 in the gut (17).  

A similar association of increased viral disease severity with lower F. prau has been seen in flu (H1N1) patients (18).  

Decreases in F. prau numbers have not been shown to be associated with infectivity. In another study, individuals with high Covid-19 infectivity had lower abundances of Parabacteroides merdae, Bacteroides stercoris, Alistipes onderdonkii and Lachnospiraceae bacterium 1_1_57FAA (19). However, given that lower numbers of F. prau, Alistipes and Lachnospiraceae bacterium 1_1_57FAA were common across multiple independent studies, this suggests these bacteria occupy guilds that are relevant to mitigating the severity of Covid-19 symptoms. 

Modulating the gut microbiome may be a solution to decrease risk and severity of Covid-19 infection (20, 21) What can be done to address microbiome dysbiosis and increase F. prau numbers? Decreased hygiene and cleanliness has been associated with an increased microbial diversity and decreased Covid-19 susceptibility (22). Conversely, social distancing and its commensurate decrease in microbial transfer and acquisition has been posited to lead to a dangerous decrease in microbial diversity (23). However, decreasing hygiene and social distancing are dangerous, as they are associated with other larger risks (22, 23). A more viable alternative to increase microbial diversity for decreased Covid-19 symptom severity is through food (20). 

The use of probiotics, live microorganisms that confer health benefits when consumed, has been suggested as a viable strategy (20). Indeed, The Natural Health Committee of China has promoted this course of action (20). Similarly, some of the researchers who first definitely established the link between Covid-19 severity and gut microbiota have attempted to create probiotic supplements for this purpose (24). However, F. prau is highly oxygen sensitive and cannot be viably delivered for consumption in adequate live numbers. 

Prebiotics, food which survives digestion and reaches our large intestine to selectively increase the numbers of gut bacteria that confer health benefits, are a better proposition. Diet has been shown to increase F. prau numbers (25), particularly high carbohydrate/low glycemic impact diets (26). In terms of selectively increasing F. prau, Livaux® from New Zealand gold kiwifruit is the only prebiotic clinically shown to increase F. prau levels in individuals with low baseline levels (1). This effect has also been demonstrated in vitro (27). Livaux contains high methoxy pectin, and high methoxy pectic galacturonic acid is a substrate used by F. prau (28). 

An M-SHIME® gut model using Microbiome Labs® synbiotic formulation including Livaux® and Actazin® shows an increase in the numbers of good gut bacteria.

Livaux® and Actazin® as a part of a synbiotic formulation were evaluated in an artificial gut system called M-SHIME®. They were shown to increase the relative abundance of Faecalibacterium prausnitzii (1), the good gut bug we call F. prau. This supports the findings from a recent clinical study using Livaux. The clinical study showed significant increases in F. prau in the faeces of participants (2). The reason this M-SHIME result was good was because it explained the clinical results using a simulation of the inner workings of our guts. This allowed the scientists to demonstrate that Livaux supports the growth of F. prau in regions of the colon not (normally) accessible for sampling without extreme medical procedures.

Livaux and Actazin are New Zealand gold and green kiwifruit powders, respectively. Both are prepared by proprietary processing methods to retain all the nutritional and functional qualities of the fruit. A key component of kiwifruit relevant to this study is pectin, a plant cell wall polysaccharide and dietary fibre (3). Pectin is one of the most complex and diverse polysaccharides in nature. It comprises many different sugars and many different linkage types between those sugars (4). The gentle processing to create Livaux and Actazin retains that structural and compositional diversity of pectin. This makes them unique amongst commercially available pectins.

Pectin escapes digestion in our small intestine and heads to our colon intact. In our colons, it serves as food for the good gut bacteria who reside there. These bacteria consume sugars using a process called fermentation. Fermentation of Livaux and Actazin pectin is slow and occurs throughout the length of the colon. This is because of the Livaux and Actazin pectin complexity and diversity, which makes disassembling it difficult (4). This means that this pectin feeds a diverse array of the resident bacteria. A diverse bacterial make up of our gut microbiomes is one of the hallmarks of good gut health (5). One of these resident bacteria which is known to consume pectin is F. prau (6).

A synbiotic is a combination of prebiotics and probiotics.

The International Scientific Association of Probiotics and Prebiotics (ISAPP) have defined a prebiotic as “a selectively fermented ingredient that results in specific changes in the composition and/or activity of the gastrointestinal microbiota, thus conferring benefit(s) upon host health” (7). Pectin is a prebiotic. Other prebiotics include non-digestible polysaccharides such as resistant starch (so-called because it resists small intestinal digestion), and fermentable polysaccharides such as xylo–oligosaccharides (XOS), galacto–oligosaccharides (GOS), fructo–oligosaccharides (FOS) and inulin (an exceptionally long variant of FOS).

XOS, GOS and FOS are chains of the sugars xylose, galactose, and fructose, respectively. The Microbiome Labs synbiotic used in the M-SHIME study contains their MegaPre™ prebiotic blend, which includes XOS from corn, GOS from cow milk, and Livaux and Actazin pectin. Unlike Livaux and Actazin pectin, XOS and GOS are rapidly fermented early in the colon. Pectin is fermented more slowly, all the way through the colon.

The definition of probiotics supported by ISAPP is “live microorganisms that, when administered in adequate amounts, confer a health benefit to the host.” Probiotics are well defined and characterised bacteria with scientifically demonstrated effects on health. They may be administered in mixtures of different strains of bacteria, or as single strains, but they are always well defined and named strains. In contrast, the live microorganisms that may be found in traditional fermented foods (e.g., kombucha, kimchi and sauerkraut) typically do not meet the ISAPP level of evidence required to be called probiotics, especially as they are often uncharacterised mixtures. They are not always well defined and named strains.

The Microbiome Labs synbiotic contains their MegaSporeBiotic™ mixture of defined Bacillus strains. These bacteria are non-pathogenic (safe). They can form spores which enable them to survive transit through the harsh conditions of our digestive tract and then grow in our colon. By growing in our colon, they favourably alter the gut conditions in a manner which confers health benefits.

Faecalibacterium prausnitzii is a commensal gut bacterium. Commensal means “to eat at the same table” and is used to refer to our resident bacteria who co-exist with us in our colon. They ferment the material we cannot digest and do us no harm. Often, they do good. F. prau is regarded as healthy for several reasons (8), not least being  production of butyrate. Additionally, gut complaints such as inflammatory bowel disease (IBD) are correlated with lower numbers of F. prau, strongly suggesting that increased numbers of these bacteria confer protection from these disorders (9). As anaerobic bacteria which cannot tolerate oxygen, they are unfortunately hard to administer live in adequate amounts to qualify as probiotics. However, it is fortunate that they do respond to pectin in our colon, and Livaux pectin in particular!

Butyrate is a bacterial fermentation by-product (10). For example, lactic acid bacteria (LAB) such as the yoghurt bacteria Lactobacillus and Bifidobacteria produce lactic acid, which in biological systems exists as lactate. Similarly, Saccharomyces yeast fermenting sugars produce ethanol as a by-product. F. prau is a member of the subset of bacteria that produce butyrate. Butyrate is absorbed by our colonocytes, the epithelial (skin) cells lining our colon. Colonocytes use it instead of glucose for respiration (to produce energy) (11).

Excess butyrate and its respiration by-products accumulate within the cells to modify cell gene expression. This regulates colonocytes’ natural life cycle progression through proliferation/growth (at low butyrate concentrations) to apoptosis (programmed cell death, at higher butyrate concentrations) (11). As cancerous colonocytes do not use butyrate for energy they accumulate higher concentrations, advancing the programmed cell death messages. This makes butyrate naturally protective against colon cancer (12). Given that colon cancers are more prevalent in the distal colon, furthest from where food enters, it is obviously beneficial to consume foods which prolong fermentation to the distal colon and promote butyrate production by bacteria such as F. prau there. For more information on butyrate, check out our blog Postbiotic: Butyrate Promote Colon Cancer Cell Death.

M-SHIME stands for Mucosal Simulator of the Human Intestinal Microbial Ecosystem (1). It models human gut digestion and fermentation of food while allowing real-time access to the inner goings on. This access is valuable, as these samples cannot be collected from human clinical participants without invasive medical procedures. The SHIME comprises five sequential bioreactor vessels simulating the stomach, small intestine, proximal colon, transverse colon, and distal colon, in that order (13). A constant flow of liquid moves through the vessels, simulating the natural movement of gut contents in a person.

The last three bioreactors are set up to contain human colonic bacteria (obtained from the faeces of healthy donors). There are different colonic bioreactors because of the natural partitioning of the colon, each with different conditions supporting the growth of different stable populations of gut bacteria (14). Food being evaluated in this system is entered into the first stomach bioreactor vessel where it will start being digested. It will be further digested in the small intestine vessel. Material which survives digestion progresses to the three colonic vessels. Here this material is sequentially fermented as it progresses through these vessels. Samples can be removed from each of these five vessels throughout the course of an experiment, which in this case was three times per week over the two weeks to establish pre-intervention baseline readings followed by four-week intervention with the synbiotic combination containing Livaux pectin.

The synbiotic combination containing Livaux and Actazin pectin showed significant, large increases in butyrate in all three (proximal, transverse, and distal colonic) SHIME compartments. There were significant corresponding increases in F. prau relative abundances (percentage of the total bacteria) in the second (transverse colon) and final (distal colon) vessels. Similar increases were not seen using the same probiotic mix in the absence of the prebiotic mix, proving these increases were due to the prebiotic being fermented.

Why do we attribute the F. prau growth to Livaux and Actazin pectin and not the other (XOS and GOS) prebiotic components? Because the balance of probability based upon previous science supports this:

Firstly, as mentioned previously we know that from people consuming Livaux (without XOS or GOS) their faecal F. prau levels are elevated (2), showing the increased abundance of this bacterium in their distal colons prior to voiding.

Secondly, F. prau can utilise highly methylated pectin core galacturonate as fuel (6), and Livaux gold kiwifruit pectin is highly methylated (3). Access to the pectin core is granted by the cooperative action of other commensal bacteria (8), which will take time. Hence the shifting of fermentation to the last two of the three compartments.

Thirdly, F. prau uses xylans poorly (6), and clinical meta-analyses suggests they do not benefit from GOS either (15). Finally, XOS and GOS, as short chain oligosaccharides comprising an average of 5-7 sugars in length, are rapidly fermentable. GOS is a well-recognised FODMAP, which are “fermentable oligosaccharides, disaccharides, monosaccharides or polyols” commonly associated with fast fermentation and resulting gas and bloating in the proximal colon (16). Thus, XOS and GOS would have been used by the bacteria in the proximal colon compartment (colon vessel one of SHIME).

The significant increases in butyrate are no doubt majorly attributable to the XOS and GOS fermentation, which would have contributed to additional bacterial numbers and activity. These additional bacterial numbers and activity support the degradation of pectin to make it accessible for F. prau, but the growth of F. prau itself is from Livaux and Actazin pectin.

Given the health-promoting role of F. prau in our gut, this is an important result, and demonstrates the importance for the internal health of our transverse and distal colons of consuming complex and slowly fermented prebiotics such as Livaux and Actazin pectin.