Taking a look at short chain fatty acid (SCFA) butyrate

Author: Leanne Mitchell

30 July 2020

 

 

What is butyrate?

Butyrate is a short chain fatty acid (SCFA) produced by gut bacteria that can breakdown (digest) fibre.  Fibre is found in plant-based foods and is largely indigestible, meaning humans do not have the enzymes to digest most fibre types which pass through to the colon or large bowel.  In the colon, the fibre is fermented by gut bacteria to produce SCFAs. Prebiotics are types of dietary fibre that act as a fuel source for health-promoting gut bacteria, producing beneficial metabolites like SCFAs.  Specific prebiotics called resistant starch and pectin have been shown to encourage the production of butyrate1,2.

Health benefits of butyrate

Butyrate supports gastrointestinal health and may be protective against some inflammation- based diseases.  The health promoting qualities of butyrate stem from its functional roles.  The functional roles of butyrate include:

  • Nourishing gut cells3 – butyrate is the main energy source for the gut cells that line the colon. Healthy gut cells help maintain the gut barrier function.

  • Epigenetic modification4-6 butyrate exerts immunomodulatory functions by altering the gene expression of certain immune cells (T cells) towards the production of anti-inflammatory cytokines (IL-10). Butyrate also alters the gene expression of other immune cells (macrophages) towards the production of antimicrobial peptides. In this way, butyrate both suppresses tissue inflammation and strengthens host defences against pathogens.

  • Cell signalling7,8 – butyrate stimulates specific G-protein-coupled receptors on cells in the gut that result in reduced appetite (GPR41) and anti-inflammatory signalling (GPR109A).

  • Intestinal gluconeogenesis9 – butyrate induces intestinal gluconeogenesis, releasing glucose into the portal circulation which positively regulates glucose homeostasis and hepatic glucose production.

Looking for more information on what your report can tell you?  Download the quick reference guide.

Clinical implications of low butyrate production

Insufficient butyrate production could contribute to gastrointestinal, immune or metabolic issues.  Within the colon, butyrate suppresses inflammation4,7, maintains the gut barrier function3 and protects against pathogens6.  Outside of the gut, low butyrate production can affect appetite8 and glucose balance9 with the possible negative impacts on body weight and diabetes risk. Not surprisingly, reduced butyrate levels (and/or reduced bacterial ability to degrade fibre) has been associated with inflammatory bowel disease10-13, colon cancer14,15 and insulin resistance16-18.

Clinical Interventions for low butyrate potential

Healthcare professionals should ensure sufficient prebiotic intake to support a diverse microbiome, with a focus on increasing resistant starch and/or pectin sources.

Diversity

Low microbial diversity can result in a reduced potential to produce butyrate. A less diverse microbiome may lack enough fibre degrading bacteria capable of producing adequate butyrate levels. For clients who also have low microbial diversity and/or inadequate fibre intake, increasing intake of a diverse range of plant-based foods should be encouraged.

Resistant starch

Resistant starch is found in foods such as barley, oats, legumes, whole beans and cashews. You can also encourage clients to create additional resistant starch in pasta, rice and potatoes by eating them cooled (overnight) in items such as pasta, rice or potato salads.   

The role of RS in gut disorders such as Irritable Bowel Syndrome (IBS) is still unclear. Debate exists on whether RS produces symptoms in those who are sensitive to fermentable fibres19,20. Inconsistencies are likely due to the individual uniqueness of each person’s gut microbiome.  Production of butyrate from RS sources requires a cooperative partnership between specific bacteria in the gut microbiome21. RS degrading bacteria provide intermediate products for butyrate producing bacteria21. For example, two of the species highlighted as Important Species in the Microba report Ruminococcus_E_bromii and Agathobacter rectalis are known to be a particularly efficient partnership for the conversion of RS to butyrate21. Therefore, a client’s unique microbiome together with their clinical symptoms/history are important to assess when considering RS sources to address low butyrate levels. 

Pectin

Pectin is mainly found in fruit, with some of the richest sources coming from kiwifruit, guava, citrus and berries.  Appropriate portions of these fruits tend to be well tolerated by individuals with IBS due to their slow fermentability22.   For client’s with IBS, healthcare practitioners should recommend spacing intake of these fruits by 2-3 hours, especially for those with visceral hypersensitivity and/or symptoms of bloating, gas or distension22.

Note: If nutritional advice is outside the scope of your practice, consider referring your client to a qualified specialist to gain personalised advice.  This would be particularly important if the client’s intake of fibre sources may be restricted due to conditions such as irritable bowel syndrome, coeliac disease, or food allergies/intolerances.

Interpreting butyrate potential from the Microba Insight™ Report

The Microba Insight™ Report indicates the genetic potential of a person’s gut microbiome to produce butyrate.  Using world-leading metagenomic DNA sequencing and high-quality bioinformatics Microba’s team of scientists and bioinformaticians analyse how many bacterial species have pathways to produce butyrate using the bacterial genetic information in the stool sample.  This provides a measure if the gut microbiome’s potential to produce butyrate.  It is worth noting that the client needs to consume sufficient prebiotic food sources to achieve their butyrate production potential.

Healthcare professionals can find the butyrate potential for their clients in both the Overview and Dig deeper into the detail sections of the Microba Insight™ report.  Butyrate potential is listed in the Key Insights within the Overview section of the report.  Here your client’s butyrate potential will be noted as “low”, “average” or “high” and an indication of whether this is a “good level”, “typical level” or “not a good level” is provided.  The text also provides a summary of the roles and health benefits of butyrate and lists the key food sources known to improve butyrate production. 

From the Key Insights textbox practitioners can click the link Take a deeper look at the detail associated with this insight here +” which will take them to Microbial Metabolites of the Dig deeper into the detail section of the report.  After selecting the “Short Chain Fatty Acid” heading practitioners will be presented with a bar chart depiction of the client’s potential to produce butyrate.  Clicking on the hyperlinked butyrate heading will bring up a textbox providing links to the research on butyrate for practitioners who wish to learn more.

 

 

Resources to assist Healthcare Practitioners address low butyrate levels

The team at Microba have developed two key resources to assist practitioners address low butyrate potential in their client’s results – the Prebiotic Guide and Shopping List tool. The Prebiotic Guide is an evidence-based resource which matches the bacterial species with their prebiotic fibre type.  It also provides a comprehensive list of food items by prebiotic fibre type (FOS, GOS, Inulin, Pectin, Resistance Starch, Arbinoxylan, Proanthrocyanidin). The Shopping List is found at end of the Microba Insight™ Report Overview section.  This is a list of prebiotic foods that help promote the growth of beneficial bacteria.  Clicking on the “Tell me why” link will bring up a textbox that highlights which specific prebiotic fibre types are included in the selected food item.  Both resources will allow healthcare professionals target resistant starch and pectin sources to address butyrate levels and/or increase and diversify fibre intake.

 

Looking for exclusive practitioner resources? Find clinical guides, video walk throughs and more.  Access the portal.


About the Author

Leanne Mitchell

Leanne is an Accredited Practising Dietitian and works as one of the microbiome coaches at Microba. Leanne has a developing interest in the clinical application of the gut-brain axis in gastrointestinal disorders, mental health and neuro-developmental conditions.

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