Suffering from hayfever? Try probiotics.


60 second summary

  • Hayfever affects between 10-30% of the population

Burning, swollen eyes, bothersome fatigue, nose clogged and tender…

Affecting 10-30% of the general population hayfever, medically known as allergic rhinitis, is one of the most common allergies worldwide.  

Allergic rhinitis- inflammation of the inside of the nose caused by an allergen, such as pollen, dust, mould or flakes of skin from certain animals.[1]

What causes us to feel ill in hayfever?

Immune responses which trigger us to feel ill are usually triggered by antigens. These are molecules unique to the item they are on, found on bacteria, viruses, chemicals as well as our own cells. In a healthy individual, antigens on their own cells are recognised as ‘self-antigens’ and so are not attacked. Certain immune system cells, such as dendritic cells,  process antigens from disease causing substances; Then the dendritic cells present the antigens on proteins they have on their surface called Major histocompatibility complexes.

When the antigen binds to these complexes this alarms the body of an intruder and leads to the start of the allergic reaction response.

How does our body react to the presence of a foreign molecule?

Firstly allergen specific cells called T helper cells must mature. T helper cells communicate to other cells that a dangerous substance is in the body– this allows recruitment of more immunity based cells to help. One method of communication between cells is by the release of molecules called cytokines. So T helper cells release these cytokines which are delivered on the other end of the line to B cells, which play a large role in destruction of the pathogen by producing antibodies. Antibodies are Y shaped proteins, serving a protective function by binding to antigens and neutralizing them.

However the release of these antibodies, IgE being a common example, comes at a cost as they can bind to other immunity related cells and release compounds such as histamine- the main mediator of itching. [2]

This is followed by common hayfever symptoms of include nasal itching sneezing, nasal obstruction and a runny nose.

Treatment with probiotics

Overall studies have already confirmed the therapeutic effect of probiotics in terms of inflammation. In one systematic review of several experiments looking at the use of probiotics in hayfever treatment, most showed evidence of a clinical benefit compared to a placebo. In another study the number of yearly hayfever episodes was significantly reduced with probiotic supplementation. What is still uncertain is what specific bacteria are the most effective but so far 2 strains have displayed their anti inflammatory value against hayfever in experiments:

  1. Lactobacillus paracasei– found in fermented vegetables

2. Bifidobacterium longum– found in certain strains of yoghurt. [3]

It is important to note however that the effect of the probiotics is lagged because it takes time for the gut to be colonized. Yet if you supplement your diet with these beneficial bacteria all year round when the hayfever season comes around you should notice milder symptoms. [4]

How do these microbes affect hayfever?

Despite the mechanisms of bacterial action in allergies still remaining in question, one hypothesis is that microbes decrease the symptoms of hayfever by increasing the proportion of regulatory T cells. These immune response suppressing cells can control antibody producing B cells ,mention above, decreasing overall inflammation.

Competing with other cells for resources such as growth factors, increased proportions of these regulatory cells stimulated by the right gut bacteria may be an effective method in control and containment of hayfever.  

[1] NHS. (2019). Allergic Rhinitis. [online] Available at: [Accessed 12 Jul. 2019].

[2] PMC. (2010). The Pathophysiology, Diagnosis and Treatment of Allergic Rhinitis. Available at: [Accessed 12 Jul. 2019].

[3] PMC. (2016). A Systematic Review and Meta-analysis of Probiotics for the Treatment of Allergic Rhinitis. [online] Available at: [Accessed 12 Jul. 2019].

[4] PMC. (2010). Probiotics in Treatment of Allergic Rhinitis. [online] Available at: [Accessed 12 Jul. 2019].

Your gut bacteria on fermentation: a matter of survival


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: [Accessed 10 Jul. 2019]. [2] Thoughtco. (2019). The Difference Between Fermentation and Anaerobic Respiration. Available at: [Accessed 10 Jul. 2019].

[3] Pink Monkey. (n.d.). Fermentation. [online] Available at: [Accessed 10 Jul. 2019].

Reduce your cholesterol levels with probiotic kefir


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: [Accessed 9 Jul. 2019].

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

[3] Wikipedia. (2019). Kefir. [online] Available at: [Accessed 9 Jul. 2019].

[4] Karger. (2018). Mechanisms of Action of Kefir in Chronic Cardiovascular and Metabolic Diseases. [online] Available at: [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: [Accessed 9 Jul. 2019].

[6] Frontiers in Microbiology. (2016). The Microbiota and Health Promoting Characteristics of the Fermented Beverage Kefir. Available at: [Accessed 9 Jul. 2019].

[7] PMC. (2012). Cholesterol-Lowering Probiotics as Potential Biotherapeutics for Metabolic Diseases. [online] Available at: [Accessed 9 Jul. 2019].

[8]Cultures for health. (2019). Reducing The Lactose Content Of Kefir. [online] Available at: [Accessed 9 Jul. 2019].