Stool transplants- a new dawn for obesity treatment?

Uncategorized

60 second summary

  • Stool transplants are also known as fecal microbial transplants (FMT’s)
  • They involve the transfer of stool from a healthy individual to the intestines of an ill person
  • Microbes present in the stool colonise the ill persons gut and have the potential to restore balance
  • Studies in mice have shown FMT’s can reverse obesity

Treating obesity with a stool transplant

The past few centuries have seen a rapid incline in metabolic disorders, amongst others- type 2 diabetes, hypercholesterolemia (high cholesterol) and heart disease. It is recently emerging that aside from genetic, lifestyle and environmental factors, the microbes residing in the gut play a large role in the regulation of these maladies.

Studies in mice have shown that there is more to altering a person’s microbial make-up than just by diet which only accounts for 57% of variation- other lifestyle alterations such as feeding patterns and sleep cycles also play a large role.

Main modifications

Modification of a persons microbiome can be achieved through 3 main interventions-

  1. Taking prebiotics such as dietary fiber
  2. Taking probiotics- so beneficial bacteria
  3.  Fecal transplant

Fecal microbiota transplant- transfer of stool from a donor to the  intestines of a recipient to restore bacterial balance. [1]

Fecal transplant intervention

This procedure has been used since the 4th century in the treatment of Clostridium difficile (diarrhea)  where in the Chinese Dong-jin dynasty administration of a stool suspension by mouth to patients with diarrhea yielded positive results.[2] Fecal transplantation is an alternative to antibiotic treatment with some studies showing a 91% primary cure rate. The procedure involves the transplant liquid being administrated into your large intestine through the anus.

Endoscope- a long thin flexible tube used inserted into the body

Fecal transplants and obesity

One area of recent interest has been the treatment of obese individuals with faecal transplants from their lean counterparts. So far, studies have suggested that microbes in the obese, thought to be of the phylum Firmicutes, are more effective at extracting energy from foods. Associations have been made between the increase of Firmicutes bacteria and decreased Bacteroidetes with increasing body mass index. (BMI)[3]

BMI- measure that uses your height and weight to work out if your weight is healthy.[4]

Experiments have found correlations between an increase in Bacteroides and weight loss[5] therefore it seems viable to suggest that altering one’s microbiome through a fecal transplant could potentially have therapeutic and potentially curative effects.

How would a fecal transplant cure obesity?

The first question to answer is what is the cause of obesity? Despite this having a variety of plausible answers one of the most plausible is insulin resistance.

Insulin resistance- when your body doesn’t respond properly to the hormone insulin which is important in removing glucose from your bloodstream into storage.

People suffering with obesity hare said to have low insulin sensitivity which means larger doses of insulin are required to lower blood glucose than in a healthy individual. In studies obesity and insulin resistance in rats has been reversed with fecal microbial transplants.

The scientific mechanisms for this dramatic change is still in question, but 1 thing is known for sure- Microbes play a large role in metabolism of glucose and fat, and this is through a protein found in the liver and intestines called the Farnesoid X receptor (FRX). This receptor works by binding to hormone regulating parts of DNA in a cell’s nucleus affecting gene expression… and it is the microbiome which activates FRX by metabolizing of primary bile acids  to secondary bile acids.[6]

All in all much more research into fecal microbial transplants must be undertaken to satisfy safety and ethical demands of the public but it is a promising technique with life changing potential.


[1] NHS Foundation Trust. (n.d.). Faecal microbiota (stool) transplantation (FMT). [online] Available at: https://www.guysandstthomas.nhs.uk/resources/patient-information/infection/fmt.pdf [Accessed 15 Jul. 2019].

[2] Research Gate. (2012). Should We Standardize the 1,700-Year-Old Fecal Microbiota Transplantation?. [online] Available at: https://www.researchgate.net/publication/233537625_Should_We_Standardize_the_1700-Year-Old_Fecal_Microbiota_Transplantation [Accessed 15 Jul. 2019].

[3] PMC. (2017). Association between body mass index and Firmicutes/Bacteroidetes ratio in an adult Ukrainian population. [online] Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5440985/ [Accessed 15 Jul. 2019].

[4] NHS. (2016). What is the body mass index (BMI)?. Available at: https://www.nhs.uk/common-health-questions/lifestyle/what-is-the-body-mass-index-bmi/ [Accessed 15 Jul. 2019].

[5] Research gate. (2007). Microbial Ecology: Human gut microbes associated with obesity. Available at: https://www.researchgate.net/publication/6617713_Microbial_Ecology_Human_gut_microbes_associated_with_obesity?enrichId=rgreq-12bd6ba98811af7d0172fb9c544799a1-XXX&enrichSource=Y292ZXJQYWdlOzY2MTc3MTM7QVM6MTYzMzU3Njc2MDIzODA5QDE0MTU5NTg5MTM1ODc%3D&el=1_x_2&_esc=publicationCoverPdf [Accessed 15 Jul. 2019].

[6] Wikipedia. (n.d.). Farnesoid X receptor. [online] Available at: https://en.wikipedia.org/wiki/Farnesoid_X_receptor [Accessed 15 Jul. 2019].

Differentiating good and bad bacteria: The wonders of your immune system

Immunity

Our body, in particular our gastrointestinal tract, is host to billions of microbes. Some of them such as Bifidobacterium are beneficial, preventing gut inflammation[1], whilst others like Staphylococcus aureus are notorious for potentially leading to fatal diseases such as sepsis.[2]

Sepsis-   the body’s overwhelming and life-threatening response to infection that can lead to tissue damage, organ failure, and death. In other words, it’s your body’s overactive and toxic response to an infection.[3]

Our immune system must be able to differentiate between the favourable and the threatening– and this response is mediated by T cells.

What are T cells?

T cells are a type of immunity related cell produced in the thymus with around 50000000 formed every day. Yet only around 2-4% of these leave thy thymus alive and mature. Why is this? Because of a process called T cell education.

thymus- an organ located behind the breastbone playing an important part in immunity and hormonal regulation

What is T cell education?

A selection process ensuring that T cells can differentiate your own cells from foreign cells. There are 2 steps to this process:

The first kills off the T cells which don’t recognise your own Major Histocompatibility complex at all.

Major Histocompatibility complex- Molecule monitoring the surface of your own cells

The second step eliminates those cells which are too attracted to your own Major Histocampatibility complex. [4]

This process occurs in the thymus and protects your own cells. But what about protecting bacteria? They may live in you, but are their own separate cells.

T cell education- but in the gut!

In the gut a similar process occurs. Cells called innate lymphoid cells educate T cells and are able to form a physical barrier between immune system cells and beneficial bacteria, thereby protecting them.

The importance of innate lymphoid cells have been also studied in gut disorders such as Crohn’s disease.

Crohn’s disease- chronic inflammation of the lining of the digestive system.

In one study individuals with this disease had Innate lymphoid cells lacking specific molecules responsible for the education of T cells. [5] Therefore T cells could attack the gut as well as its bacteria causing inflammation.

Overall a healthy immune system plays a large role it protecting not only our own cells and own health, but also our microbial residents.


[1] Healthline. (2016). 10 Ways to Improve Your Gut Bacteria, Based on Science. [online] Available at: https://www.healthline.com/nutrition/improve-gut-bacteria#section2 [Accessed 12 Jul. 2019].

[2] NIH. (2018). Probiotic bacteria block harmful microbe. Available at: https://www.nih.gov/news-events/nih-research-matters/probiotic-bacteria-block-harmful-microbe [Accessed 12 Jul. 2019].

[3] Sepsis Alliance. (n.d.). Definition of Sepsis. [online] Available at: https://www.sepsis.org/sepsis-basics/what-is-sepsis/ [Accessed 12 Jul. 2019].

[4] InterPro. (2019). Major Histocompatibility Complex. [online] Available at: https://www.ebi.ac.uk/interpro/potm/2005_2/Page1.htm [Accessed 12 Jul. 2019].

[5] American Microbiome Institute. (2015). Immune system cells are educated in the gut to not attack beneficial gut bacteria. Available at: http://www.microbiomeinstitute.org/blog/2015/4/28/immune-cells-are-educated-in-the-gut-to-not-attack-beneficial-bacteria [Accessed 12 Jul. 2019].

Molecular Mimicry- How your gut bacteria trick your immune system!

Uncategorized

60 second summary

  • Some bacteria have proteins on their surface which mimic those on our own cells
  • They play a crucial role in preventing gut related inflammatory diseases.

The gut and immunity

It has been known for a while that the gut plays a large role in protection against disease: About 80% of the immune system resides inside the gut[1] alongside your microbial community, which also play a protective role by several mechanisms such as  regulation of T cells.[2]

T cells- cells playing a vital role in defense against pathogens .

T cells can distinguish between disease causing cells and safe cells via antigens.

Antigens-molecules found on cells providing information about whether or not the cell is dangerous or infected- in short deciding its fate- should it stay alive?

Recent evidence has shown that some bacteria serve a protective function through mimicking our own antigens.

IGRP206–214   is an antigen found in mice found on cells in the pancreas called islets of Langerhans cells. These cells play a large role in the control of blood sugar levels and development of diseases such as diabetes. One of the functions of this IGPR antigen is to encourage the activity of a subset of immune cells called CD8+ T cells.

CD8+ T cells- (also known as cytotoxic lymphocytes) kill infected cells by mechanisms such as release of toxic granules called perforins into the cell leading to its death.[3]

One of the functions of CD8+T cell is to suppress disease by targeting the destruction of cells presenting the foreign antigens rather than the pancreas’ beta cells.

A type of antigen on the microbial strain Bacteroides called Bacteroides Integrase has been shown to mimic the IGPR protein.  [4]

Quick introduction to Bacteroides

Bacteroides are a species generally beneficial as long as they’re residing inside the gut. However when they esacpe can cause bacteremia which is the presence of bacteria in the bloodstream which is dangerous. Generally these microbes play important roles ,such as in terms of digestion, by fermenting carbohydrates so that can be used as host energy souce. Germ free animals need 30% more calories to maintain body mass than normal mice.

Function of bacterial integrase

The integrase protein found on Bacteroides therefore is able to mimic the IGRP antigen and induce the T cells to kill infected cells rather that the body’s own insulin producing cells which is one of the causes of diabetes.

Another effect of the Bacteroides integrase in mimicking the IGPR antigen is reduction of colitis.

Colitis- inflammation of inner lining of colon. [7]

The mechanism behind this is as follows: Like IGPR, Bacteroides integrase recruits CD8+ cells. This reduces colitis because the stimulated CD8+ cells target inflammation inducing cells called dendritic cells .

Dendritic cells- antigen presenting cells which can lead to the stimulation of an immune response.

One way in which these cells cause inflammation is by over production of TNF alpha which is a molecule also associated with premature cell death. [5]

Overall this contributes to maintenance of a normal immune system.


[1] Institute of health sciences. (n.d.). Probiotics help as 80% of Immune System in your GI Tract. [online] Available at:

Probiotics help as 80% of Immune System in your GI Tract
[Accessed 13 Jul. 2019].

[2] BMJ journals. (2018). Imitation is the best form of… treating IBD?. Available at: https://gut.bmj.com/content/67/2/389 [Accessed 13 Jul. 2019].

[3] British society of Immunology. (n.d.). CD8+ T Cells. Available at: https://www.immunology.org/public-information/bitesized-immunology/células/cd8-t-cells [Accessed 13 Jul. 2019].

[4] MassiveSci. (n.d.). How gut bacteria manipulates your immune system – by mimicking it. Available at: https://massivesci.com/articles/gut-bacteria-immune-system-protein-language/ [Accessed 13 Jul. 2019]./

[5] Wikipedia. (2019). Tumour necrosis factor. [online] Available at: https://en.wikipedia.org/wiki/Tumor_necrosis_factor_alpha [Accessed 13 Jul. 2019].

[6]Research gate. (2017). A Gut Microbial Mimic that Hijacks Diabetogenic Autoreactivity to Suppress Colitis. [online] Available at: https://www.researchgate.net/publication/320513212_A_Gut_Microbial_Mimic_that_Hijacks_Diabetogenic_Autoreactivity_to_Suppress_Colitis [Accessed 13 Jul. 2019].

[7] MedicineNet. (n.d.). Colitis. [online] Available at: https://www.medicinenet.com/colitis/article.htm [Accessed 13 Jul. 2019].

Suffering from acne? Discover the curative effects of your gut microbes

Skin

60 second summary

  • Probiotics are microorganisms beneficial for maintaining a healthy gut bacteria community
  • Acne can be caused by hormonal and inflammatory imbalances
  • Supplementing with fermented foods such as yoghurt and saukraut may balance cells in the body responsible for inflammation control.

What causes acne?

Acne is a skin condition affecting 85% of individuals between the age of 12 and 25.

The science: It is can be caused by several factors: excess secretion of sebum, an oily substance produced by the skin; release of molecules causing inflammation or hyperkeratosis.

Hyperkeratosis-  when the protein keratin builds up in the connective tissue surrounding a hair.

Onset

Acne is a multifactorial disorder which means several aspects of your life can influence whether you acquire it. One suggestion is a diet too high in refined carbohydrates because of their high glycemic load.

Glycemic load- a measurement of the quantity of sugars in a portion of food alongside how fast it raises your blood glucose levels.[1]

The science: A diet with a high glycemic load is known to increase acne-triggering molecules such as IGF-1 (insulin like growth factor 1). Additionally IGF-1 promotes release of hormones such as testosterone with increases production of oils in the skin.[2]

Treatment

The usual treatment for acne is the use of broad spectrum antibiotics yet this is not only a long process but also comes hand in hand with side effects such as unpleasant changes in skin color. Over the past few years the use of probiotics to treat skin conditions has become a hot topic in medical research. Probiotics are microorganisms which can alter and restore health to your gut microbiome due to their anti-inflammatory and anti-microbial effects.

In one study on 300 patients supplemented with L. acidophilus and Lactobacillus bulgaricus, 80% of the patients showed clinical improvement in their acne. In another experiment patients taking Lactobacillus and Bifidobacterium supplements in addition to antibiotics had significantly less acne lesions than the group just on antibiotics.

How?

Probiotics are known to decrease inflammation through regulating the release of molecules like interleukin 1 alpha, a type of pro-inflammatory cytokine.

Inflammatory cytokines- substances affecting the body’s reaction to infection and disease and can be pro-inflammatory, making the disorder worse or anti-inflammatory, promoting healing.

The science: Therefore by decreasing release of interleukin 1 alpha, probiotics can decrease skin trauma.

Another mechanism by which probiotics act is by balancing the ratio of cells important in immune function such as T cells, where T stands for thymus because it is where the cells mature. Effector T cells defend the body through mechanisms like cell death, whilst regulatory T cells suppress the formation of effector T cells. An imbalance between these may lead to autoimmune disorders, one of which is of course acne.

Acne and stomach acid?

Another association between acne and gut microbe problems relates to the hydrochloric acid in one’s stomach. The acid’s function is not only to help in food digestion but also to prevent growth of unwanted bacteria. Studies have shown people with acne and inflammation of the skin are likely to have hypochlorhydria.[3]

Hypochlorhydria- production of too little hydrochloric acid.

The science: This leads to the migration of microbes from the large intestine ( the terminal part of the digestive tract) upwards, to the small intestine where they can impair one’s absorption of nutrients like zinc. Research has confirmed people with acne have lower levels of zinc in their blood than those with clear skin. [4]

The bacteria shown to control acne to the greatest extent are: Staphylococcus, Streptococcus, Lactococcus, Lactobacillus, and Enterococcus. Interested in controlling your outbreaks? Try supplementing your diet with probiotics such as:

1. Kefir

2. Sauerkraut

3. Pickles

Enjoy!


[1] Diabetes.co.uk. (n.d.). Glycemic Load. [online] Available at: https://www.diabetes.co.uk/diet/glycemic-load.html [Accessed 10 Jul. 2019].https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6048199/

[2] International Journal of Microbial Sciences. (2017). Edible Plants and Their Influence on the Gut Microbiome and Acne. Available at: https://www.mdpi.com/1422-0067/18/5/1070 [Accessed 10 Jul. 2019].

[3] PMC. (2018). The Gut Microbiome as a Major Regulator of the Gut-Skin Axis. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6048199/ [Accessed 10 Jul. 2019]. c

Your gut bacteria on fermentation: a matter of survival

Probiotics

60 second summary

  • Fermentation is the process by which bacteria release energy
  • Its it is important in allowing the recycling of molecules to restart the biological cycle for energy release
  • Fermented food tastes sour because of the lactic acid produced by bacteria in fermentation

Fermentation- a word we commonly hear associated with yoghurt, beer, sauerkraut and more. But what does it actually mean? Fermentation is a type of biological mechanism called respiration, which you’ll be an expert on after reading the below article.

What is respiration?

Respiration- the release of energy in living organisms

Overall, this may be classified into to main categories:

  • Aerobic respiration= with oxygen
  • Anaerobic respiration and fermentation= without oxygen.

Some cells are unable to respire using oxygen because they do not have the correct genes or enzymes required . An example or a anaerobic bacterium is E.coli.

Some organisms have evolved the adaptation that if environmental conditions change and oxygen does become available, they may switch on genes allowing them to respire aerobically .[1] These are called facultative organisms.

ATP- the energy currency in cells

In cells some ATP is produced via a mechanism called glycolysis, which is a fancy word for the breaking down of the sugar glucose.

If oxygen is present, aerobic respiration can occur. If it is not either fermentation or anaerobic respiration occurs.

The main difference between the two is that the fermentation produces lactic acid ( which is what causes cramps during exercise! )whilst anaerobic respiration’s final product is a molecule called pyruvate.

Glycolysis can continue again and again in an endless cycle even without any oxygen. But how can this be?

Surely all organisms need oxygen to survive? The answer is that required molecules are regenerated, essentially a recycling system. Many biological systems work on opposites to balance reactions out.

The science– In glycolysis a molecule called NAD+ is reduced forming NADH. Later the same molecule is oxidised reforming NAD+ [2].

Oxidation= loss of electrons

Reduction= gain of electrons

They are opposites!

Energy production in respiration with vs without oxygen

Respiration without oxygen releases 2 molecules of ATP per glucose molecules. This may seem reasonable but in the presence of oxygen 38 ATP’s per glucose can be formed, making aerobic respiration much more efficient.

Fermented foods

One of the reasons why many fermented foods taste sour is because of lactic acid produced as a by product of fermentation.

The science: The equation which summarises the process, is as follows:

Pyruvate  +  NADH ↔ lactic acid  + NAD+ [3]

Note that the through fermentation the NAD+, a substrate in the initial step of glucose breakdown mentioned above, is reformed!

Common lactic acid producting bacteria include Lactobacillus Leuconostoc and Streptococcus.

Types of fermentation

Overall there are 2 types of fermentation.

  1. Homolactic fermentation- where the only product is lactic acid. Commonly used in yoghurt production
  2. Heterolactic fermentation- where lactic acid, ethanol and carbon dioxide is produced. Seen in fermentation of vegetables like cucumbers into pickles.

The particular flavour of each fermented food is determined by the types of other organic acids produced in side reactions.

Overall, fermentation is an essential pathway for keeping bacteria alive as it allows the regeneration of molecules for respiration, the release of energy. Humans take advantage of this process by fermenting foods which portrays its benefits as an ancient preservation process as well as taste enhancer and a superb probiotic!

[1] Openstax. (n.d.). Microbiology. [online] Available at: https://cnx.org/contents/5CvTdmJL@7.1:XjvIvG9J@4/8-4-Fermentation [Accessed 10 Jul. 2019]. [2] Thoughtco. (2019). The Difference Between Fermentation and Anaerobic Respiration. Available at: https://www.thoughtco.com/difference-between-fermentation-and-anaerobic-respiration-1224609 [Accessed 10 Jul. 2019].

[3] Pink Monkey. (n.d.). Fermentation. [online] Available at: http://pinkmonkey.com/studyguides/subjects/biology-edited/chap5/b0505601.asp [Accessed 10 Jul. 2019].

Reduce your cholesterol levels with probiotic kefir

Probiotics

60 second summary

  • Kefir is a drink made by fermenting milk
  • Lactobacillus is one bacteria thought to decrease cholesterol levels
  • Gut microbes can ever alter cholesterol production by altering our DNA through the release of molecules called short chain fatty acids


What is kefir?

Kefir is a type of fermented cow’s milk drink with a slightly acidic flavor and thick consistency. Its unique texture is caused by kefiran which is an exopolysaccharide.[1]

Exopolysaccharide-  a large molecule made of sugar which are secreted by microbes into the extracellular environment.

Its health beneficial functions are driven by its ability to balance out communities of gut bacteria, a feature shared by other probiotic foods such as yoghurt and saukraut.

How is kefir made?

Commercially, kefir is made in bulk by fermenting milk using starter cultures of microbes which allows the products to be consistent but traditional kefir making requires a kefir grain. [2]A kefir grain is made up of long sugar chains such as kefiran mentioned above. It provides a perfect environment for the proliferation of yeast cultures and bacteria which live in a symbiotic relationship in other words, a close physical association.

The main bacterial strains include Lactobacillus , Lactococcus ,Streptococcus and Leuconostoc, whilst the main yeast species are Saccharomyces, Kluyveromyces, and Candida.[3]

One of kefir’s most studied properties is its effects on cardiovascular health in particular cholesterol levels.

Cholesterol – type of lipid and despite its often negative connotations, is an essential component of cell membranes and a precursor in production of molecules such as vitamin D.

Kefir and cholesterol synthesis modification

The science: Cholesterol can of course come from diet but 80% of it is produced in the liver and intestines. High cholesterol, also called hypercholesterolemia, is dangerous because it may form fatty deposits in arteries leading to them narrowing and potentially becoming obstructed. In experiments with animals, fermented milk products have shown to decrease serum cholesterol levels by 41-84% , decrease its production by the liver, as well as increase its excretion as bile, a dark yellow fluid.

Serum cholesterol- measurement of blood cholesterol levels

Which bacteria in kefir is thought to affect cholesterol levels?

On of the main bacterial strain thought to be majorly responsible for the altered biological mechanisms is Lactobacillus.[5]

Lactobacillus is a type of probiotic which resides in areas of the digestive tract like the small intestine where it affects the metabolism of bile acids and cholesterol.

The science– In the intestine Lactobacillus is able to produce enzymes which deconjugate bile acids, increasing the rate by which they are excreted from the body.

Deconjugation- a reaction disrupting a system of conjugated double bonds

Cholesterol itself is made of bile acids and to replace the bile which was excreted, it converts itself to the acids thereby reducing its overall concentration.[7]

Other excreted products also include propionic acid which decrease cholesterol synthesis by inhibiting one of the steps in the biosynthesis pathway. [4]


How do bacteria affect cholesterol metabolism on a genetic level?

Molecules released by bacteria in kefir are able to modify the production and degradation of chemicals our body produces naturally.

The science– In one study, the Niemann-Pick C1-like 1 (NPC1L1) gene, a crucial gene in absorption of cholesterol was shown to be downregulated where rats were fed bacteria present in kefir.[6] Gut bacteria can modify production of proteins in our body through release of molecules called short chain fatty acids.

Overall, kefir is a simple and effective dietary component which acts as a probiotic enhancing your gut microbial flora. Interestingly, it is even suitable for those who are sensitive to dairy products because despite being based on milk, the lactose in it is consumed by the culture releasing acids and a pleasant tangy flavour. [8] It should be available to buy in regular supermarkets or in European food stores. Enjoy!


[1] PMC. (2016). The Microbiota and Health Promoting Characteristics of the Fermented Beverage Kefir. [online] Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4854945/ [Accessed 9 Jul. 2019].

[2] Dr Axe. (2019). 7 Kefir Benefits, Including Boosting Immunity and Helping to Heal the Gut. [online] Available at: https://draxe.com/kefir-benefits/ [Accessed 9 Jul. 2019].

[3] Wikipedia. (2019). Kefir. [online] Available at: https://en.wikipedia.org/wiki/Kefir [Accessed 9 Jul. 2019].

[4] Karger. (2018). Mechanisms of Action of Kefir in Chronic Cardiovascular and Metabolic Diseases. [online] Available at: https://www.karger.com/Article/FullText/492511 [Accessed 9 Jul. 2019].

[5] PLOS ONE. (2018). Cholesterol-lowering effect of Lactobacillus rhamnosus BFE5264 and its influence on the gut microbiome and propionate level in a murine model. Available at: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0203150 [Accessed 9 Jul. 2019].

[6] Frontiers in Microbiology. (2016). The Microbiota and Health Promoting Characteristics of the Fermented Beverage Kefir. Available at: https://www.frontiersin.org/articles/10.3389/fmicb.2016.00647/full [Accessed 9 Jul. 2019].

[7] PMC. (2012). Cholesterol-Lowering Probiotics as Potential Biotherapeutics for Metabolic Diseases. [online] Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3352670/ [Accessed 9 Jul. 2019].

[8]Cultures for health. (2019). Reducing The Lactose Content Of Kefir. [online] Available at: https://www.culturesforhealth.com/learn/milk-kefir/reducing-lactose-content-kefir/ [Accessed 9 Jul. 2019].

Prebiotics- an essential for your colon’s health

Prebiotics

60-second summary

  • Prebiotics are types of fiber which enhance growth of beneficial gut bacteria
  • Gut bacteria release metabolically important molecules such as short chain fatty acids
  • Short chain fatty acids decrease small intestinal pH, therefore making the lower digestive tract less susceptible to disease causing microorganisms

What are prebiotics?

Prebiotics are types of fiber which escapes digestion in the upper gut and can affect the proliferation and ecosystem of bacteria mostly residing in the large bowel, which feed off our undigested carbohydrates. Generally carbohydrates are classified in terms of their chain length where the prefix is the number of molecules in the chain:

mono- meaning one

di- meaning two

oligo- meaning 3-6

poly- meaning more than six

and the suffix being -saccharide, from Latin saccharum meaning sugar.[1]Our main source of prebiotics comes from oligosaccharides which are plant derived carbohydrates such as beta glucans found in oats. Archaeological analysis of preserved faeces of hunter gatherers has shown us a typical male would consume an average of 135g of inulin a day, a prebiotic found in several root plants such as chicory and garlic. [2]

Main bacteria involved:

The main bacteria involved in the fermentation of prebiotic fiber are Bifidobacterium and Lactobacillus, which contain several genes encoding enzymes that break down carbohydrates. In terms of digestion, these enzymes act as biological scissors, breaking the bonds between individual sugars in a chain so that they may be more easily absorbed.

In comparison to the microbiome the human body itself contains a miniscule amount of its own carbohydrate digesting enzymes: certain bacteria such as Bacteroides thetaiotaomicron can produce 260 alone! The bacteria benefit from this sugar fermenting process because it releases energy which they need for survival and proliferation, such that for every 100g of carbohydrate fermented 30g of bacteria is produced. Our interaction with the bacteria is certainly a two way contract because we too benefit from them releasing important biological molecules such as short chain fatty acids (SCFA).[3]

Short chain fatty acids- fatty acids with less than 6 Carbon molecules produced by bacterial fermentation in the large intestine

Prebiotics and short chain fatty acids

One of the main functions of SCFA is promoting a healthy large intestine. Your large intestine is a tube absorbing water and storing faeces until they are ready to be released. An imbalanced microbiome can’t serve its protective function against inflammatory diseases such as IBS (irritable bowel syndrome) which is estimated to affect 2 in 10 people in the UK[4].

Bowel- section of the digestive tract including the small bowel (small intestine) and large bowel (large intestine and rectum)

Given their acidic nature, Short chain fatty acids decrease the pH of the colon reducing the risk of proliferation of dangerous bacteria. Arguably the most important SCFA for colon health is butyrate which is the preferred metabolic fuel for colonocytes.

Colonocyte- cell lining the large intestine/colon

In laboratory experiments butyrate has also shown to promote DNA repair in colonocytes, reducing the risk of colonic carcinogenesis, in other words cancer of the small intestine. [5]

Common prebiotic food examples

  1. Garlic-11% of its fiber content is prebiotic
  2. Barley-contains 3-8g of beta glucan per 100g serving
  3. Apples– 50% of their fibre contant comes from pectin[6]

Harms?

Just like with any food, prebiotics should be eaten in moderation. Introducing them to your diet may initially induce bloating and gas production as a result of carbon dioxide and hydrogen gases being produced from bacterial fermentation, but don’t let this put you off! It is only temporary and a sign your microbiome is flourishing but note that if you do feel unusually unwell consult your doctor as soon as possible.

Remodel your microbiome, revolutionise your health, reconstruct your life



[1] https://www.britannica.com/science/oligosaccharide

[2] https://en.wikipedia.org/wiki/Prebiotic_(nutrition)

[3] https://www.medicalnewstoday.com/articles/323490.php

[4] https://www.bupa.co.uk/health-information/digestive-gut-health/irritable-bowel-syndrome

[5] http://apjcn.nhri.org.tw/server/APJCN/5/1/15.htm

[6] https://www.healthline.com/nutrition/19-best-prebiotic-foods#section11