The answer is yes, probiotics can help your immune system. And in this article, we’re going to try and get up to date with the various ways that different probiotics might be able to build your immune response.
Helping allergic and viral conditions such as the common cold and COVID-19 in the process.
If you are a regular reader on the site, you’ll have read before how the digestive system houses seventy per cent of the immune system.[1]
Let’s define what we mean by immunity for the context of this article. The easiest way to look at how probiotics help is by bringing balance to the bacterial community or microbiome. This balance assists with viral, allergic, and other conditions like inflammatory bowel disease and autoimmune disorders, for instance.[2]
Building on that, researchers from Chinese University in Hong Kong have found that forty per cent of people diagnosed with COVID-19 have a form of dysbiosis or imbalance of bacteria in their digestive systems.[3]
Furthermore, that imbalance in gut bacteria contributes to the severity of COVID-19, which underscores just how much the microbiome can influence our immunity.
Let’s start with some basics around probiotics and their role in the immune system and come back to a more detailed look at COVID later.
In previous articles, we’ve looked at the two parts of the immune system, innate and adaptive immunity. An easy way to understand the innate immune system is as the body’s first line of defence. For example, organs like the skin are part of the innate immune system.
In contrast, the adaptive immune system, which often acts after the innate immune system, is specific in its behaviour. For example, T and B lymphocytes, whose function is to respond to specific antigens.[4]
Probiotics play a critical role in maintaining the delicate balance between the innate and adaptive immune systems.[5]
This balance allows the body to tolerate many potential antigens entering the body via the food we eat or the air we breathe.
Notice that we are using probiotics precisely when addressing gut bacteria’s role in promoting an immune response. This specificity is because one of the key definitions of a probiotic is that as a live organism that benefits the host.[6]
The reason to differentiate is that some bacteria which make up the microbiome cause undesirable immune responses, such as autoimmunity.[7]
Isn’t that crazy?
Bacteria in your gut can turn inflammation “on” or “off.”
The way they do this is a little too complex for this article. But let’s look at specific probiotic strains that we can rely on to help improve the immune system’s desirable parts that protect our bodies from the outside world.
Remember our innate immune systems? The first line of defence?
Well, this is the first place where we can see probiotics strengthen the immune system’s resolve.
And it starts in your saliva!
Yep, one of the critical components of your barrier immunity is an immunoglobulin called Secretory IgA. It appears in high concentrations in your saliva and stomach and plays a huge role in managing your sensitivity and tolerance to food.[8]
The way I explain its role to patients is to imagine a Lord of the Rings type affair where an army is approaching a castle ready for battle, and the archers appear ready to fire first.
Well, if you’re still with me (a pretty big assumption that everyone has watched Lord of the Rings!), then secretory IgA are the archers of the immune system, and when they encounter an antigen from food entering the mouth, for example, their job is to attack first, hence the term, barrier immunity.
One of the lesser-known probiotics, Saccharomyces boulardii, is often used in natural medicine to boost this essential immune cell.
Its ability to increase secretory IgA is amplified by an anti-inflammatory effect that has been beneficial in different bacterial infections and symptomatic relief in inflammatory bowel conditions such as Crohn’s disease (CD), for example.[9]
Further, S.boulardii can also interfere with the growth of undesirable pathogens that cause imbalance within the bacterial community, such as Candida albicans, Yersinia enterocolitium, H.pylori and more pathological bacterial infections such as Salmonella.[10]
This ability to interfere with undesirable bacteria makes S.boulardii one of the best options for antibiotic-associated and traveller’s diarrhoea.[11]
Another way probiotics can help to boost your immune defence is by secreting compounds that suppress the growth of organized crime, like gram-negative bacteria in the gut.
This suppression can be significant based on the connection between gram-negative bacteria and numerous inflammatory conditions.[12]
Suppressing gram-negative bacteria and their compounds called lipopolysaccharides (LPS) is a great way to use probiotics to improve your immune response whilst reducing an overactive immune response, such as the one that occurs in allergies.[13]
A systematic review of probiotics and allergic rhinitis showed that probiotics could improve allergic rhinitis symptoms. More studies are required to ascertain which probiotics are the most helpful.[14]
Some of the common probiotic strains used in some of the studies to help with the immune response in allergic rhinitis include:[15]
- Lactobacillus acidophilus
- Bifidobactrium longum
- Lactobacillus paracasei
- Lactobacillus rhamnosus
- Lactobacillus gasseri
The good news with this list is that it looks like many professional practitioner-only brands are available, allowing you to potentially try them out for yourself or enlist the help of a practitioner to help choose the most appropriate one for you. More on that later in the article.
Let’s look at one of the hot topics of the 2020s, probiotics and viral infections.
Can probiotics help with viral infections such as upper respiratory infections or the common cold?
The answer is yes, but we are still learning how and which probiotics might be best.
Still, even a review done in the prestigious Cochrane commentary saw positive results. A review covering 13 studies that amounted to just under four thousand people found that probiotics were better than placebo in preventing upper respiratory infections, the average duration of an episode, and cold-related absence from school.[16]
Another more recent review done in 2020 looked at six randomized controlled trials totalling approximately 1500 people and found that probiotics were better than placebo, mainly at preventing the occurrence of colds.[17]
An exciting study addendum published in 2021 at the height of COVID for many countries suggested that probiotics might have a role to play in the management of the global pandemic, adding that the results of their study had shown a twenty-seven per cent reduction in colds compared to controls.
Nothing that we haven’t just said before, but this study found an important side note.
During the study, a group of people considered overweight or obese had a more significant reduction in their prevalence of colds on top of the initial results. This added effect suggests that probiotics might play a role in the comorbidity element we’ve seen to become thematic both in the global pandemic and immune deficiency in general.[18]
Is there a reason why the gut affects lung-based diseases positively?
Introducing the gut-lung axis.
We’ve got the gut-brain axis, and now we have the gut-lung axis. Recent research seemingly driven by the pandemic has highlighted the possible “crosstalk” between the digestive system and the lungs.
Interestingly, the predominant phyla in the lungs are very similar to the digestive system, mainly Firmicutes and Bacteriodetes, followed by Proteobacteria and Actinobacteria.[19]
What does this mean?
At the moment, it doesn’t mean much more than another watch this space research subject, as the studies explaining this are still very scattered. Still, with respiratory illnesses not going away anytime soon, new ideas around how probiotics can influence their outcome are undoubtedly exciting.
However, we are starting to see a connection between probiotics and COVID-19.
As we touched on at the beginning of the article, researchers at Hong Kong’s Chinese University have shed light on the role of probiotics in the management of COVID-19.
Let’s spend some time looking a little deeper into some of the details of their work and the strains of probiotics that they found to help.
One of the key themes revealed over the past 24 months was that people were experiencing multi-system effects beyond the respiratory symptoms initially associated with the virus.
The digestive system seemed to be especially vulnerable in this case,[20] with some studies noting that the ACE2 receptor for which COVID-19 has an affinity is mainly expressed in the gut.[21]
In the study we’re looking at, researchers measured the immune response (the amount of inflammation, in simple terms) and the microbiome in one hundred patients with COVID-19. Even with the small cohort, they found some interesting things.
The first was that the microbiome compositions and their imbalance seemed to be related to how many inflammatory chemicals were present in the blood, causing issues.[22]
One of the issues with this and how it relates to you is that the imbalanced bacterial environments inhibited the clearance of the virus post-infection. Something that seemingly increased the chance of post-viral complications or “long COVID,” something mirrored in a letter to the editor from the Journal of Medical Virology at the end of February 2022.[23]
Another Hong Kong-based study (go HK!), released a week or so before writing this, had a little more unsettling results. This time the researchers followed up patients who had mild to moderate COVID-19 over six months.
The most common symptoms people in the study were experiencing were fatigue, poor memory, hair loss, anxiety and difficulty sleeping. Interesting long-term symptoms from a respiratory illness?
Well, this is where the results get interesting.
People who were suffering from “long-COVID” symptoms or what the paper calls, post-acute COVID syndrome or PCAS, had distinctly lower levels of bacteria associated with immune function and higher levels of bacteria that could affect the brain and mental health symptoms listed above.[24]
The unsettling side of the results was down to the fact that even after six months, the changes in gut bacteria remained, further compounding problems. Now, this could be down to diet and stress, but the message here is specific for my readers who are here to help their gut and brain.
Even mild to moderate COVID-19 infection seems to have a lasting effect on the gut bacteria.
This lasting effect, though, can be solved using probiotics. While we have looked at probiotics in general and how they can help, a particular strain called Bifidobacterium adolescentis has shown promise in improving vaccination responses and reducing adverse effects often associated with long-COVID post-infection.[25]
Remember, though. Not all probiotics are created equally.
We’ve looked at some specific species and their contribution to immunity, but it’s important to note some best practices to follow when looking at which probiotics might help.
In the clinic, when I get asked about brands to choose from, I often say that the two supplements you should spend money on are fish oil and probiotics. I say this mainly because the manufacturing and quality control behind these formulas is expensive.
Keep your probiotics purchases to a refrigerated version with a broad selection of species from the Lactobacillus and Bifidobacterium to make sure you’re getting the right amount of diversity in the capsule.
An easy way to think about it is if you were trying to repopulate the different nationalities that make up the earth. There are so many different ones who contribute in their way that it makes sense not to focus too much on one specific species, such as L.acidophillus.
So, what do you think?
In this article, we’ve been exploring how using probiotics might be able to improve your immune activity.
Using probiotics to improve your immunity can help not only different presentations of immune disorders such as allergies and getting colds but may also be the difference in making COVID vaccines work for you and helping you recover from infection if it were to happen.
Hope it helps!
References
[1] Wiertsema SP, van Bergenhenegouwen J, Garssen J, Knippels LMJ. The Interplay between the Gut Microbiome and the Immune System in the Context of Infectious Diseases throughout Life and the Role of Nutrition in Optimizing Treatment Strategies. Nutrients. 2021;13(3):886. Published 2021 Mar 9. doi:10.3390/nu13030886
[2] Wilkins LJ, Monga M, Miller AW. Defining Dysbiosis for a Cluster of Chronic Diseases. Sci Rep. 2019;9(1):12918. Published 2019 Sep 9. doi:10.1038/s41598-019-49452-y
[3] Yeoh YK, Zuo T, Lui GC, et al. Gut microbiota composition reflects disease severity and dysfunctional immune responses in patients with COVID-19. Gut. 2021;70(4):698-706. doi:10.1136/gutjnl-2020-323020
[4] Cano RLE, Lopera HDE. Introduction to T and B lymphocytes. In: Anaya JM, Shoenfeld Y, Rojas-Villarraga A, et al., editors. Autoimmunity: From Bench to Bedside [Internet]. Bogota (Colombia): El Rosario University Press; 2013 Jul 18. Chapter 5. Available from: https://www.ncbi.nlm.nih.gov/books/NBK459471/
[5] Yan F, Polk DB. Probiotics and immune health. Curr Opin Gastroenterol. 2011;27(6):496-501. doi:10.1097/MOG.0b013e32834baa4d
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[8] Berin MC. Mucosal antibodies in the regulation of tolerance and allergy to foods. Semin Immunopathol. 2012;34(5):633-642. doi:10.1007/s00281-012-0325-9
[9] McFarland LV. Systematic review and meta-analysis of Saccharomyces boulardii in adult patients. World J Gastroenterol. 2010;16(18):2202-2222. doi:10.3748/wjg.v16.i18.2202
[10] McFarland LV. Systematic review and meta-analysis of Saccharomyces boulardii in adult patients. World J Gastroenterol. 2010;16(18):2202-2222. doi:10.3748/wjg.v16.i18.2202
[11] Pais P, Almeida V, Yılmaz M, Teixeira MC. Saccharomyces boulardii: What Makes It Tick as Successful Probiotic?. J Fungi (Basel). 2020;6(2):78. Published 2020 Jun 4. doi:10.3390/jof6020078
[12] Maldonado RF, Sá-Correia I, Valvano MA. Lipopolysaccharide modification in Gram-negative bacteria during chronic infection. FEMS Microbiol Rev. 2016;40(4):480-493. doi:10.1093/femsre/fuw007
[13] Nogueira JC, Gonçalves Mda C. Uso de probióticos na rinite alérgica [Probiotics in allergic rhinitis]. Braz J Otorhinolaryngol. 2011;77(1):129-134. doi:10.1590/s1808-86942011000100022
[14] Zajac AE, Adams AS, Turner JH. A systematic review and meta-analysis of probiotics for the treatment of allergic rhinitis. Int Forum Allergy Rhinol. 2015;5(6):524-532. doi:10.1002/alr.21492
[15] Yang G, Liu ZQ, Yang PC. Treatment of allergic rhinitis with probiotics: an alternative approach. N Am J Med Sci. 2013;5(8):465-468. doi:10.4103/1947-2714.117299
[16] Quick M. Cochrane Commentary: Probiotics For Prevention of Acute Upper Respiratory Infection. Explore (NY). 2015;11(5):418-420. doi:10.1016/j.explore.2015.07.012
[17] Li L, Hong K, Sun Q, et al. Probiotics for Preventing Upper Respiratory Tract Infections in Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Evid Based Complement Alternat Med. 2020;2020:8734140. Published 2020 Oct 26. doi:10.1155/2020/8734140
[18] Mullish BH, Marchesi JR, McDonald JAK, et al. Probiotics reduce self-reported symptoms of upper respiratory tract infection in overweight and obese adults: should we be considering probiotics during viral pandemics?. Gut Microbes. 2021;13(1):1-9. doi:10.1080/19490976.2021.1900997
[19] Enaud R, Prevel R, Ciarlo E, et al. The Gut-Lung Axis in Health and Respiratory Diseases: A Place for Inter-Organ and Inter-Kingdom Crosstalks. Front Cell Infect Microbiol. 2020;10:9. Published 2020 Feb 19. doi:10.3389/fcimb.2020.00009
[20] Zhang J, Garrett S, Sun J. Gastrointestinal symptoms, pathophysiology, and treatment in COVID-19. Genes Dis. 2021;8(4):385-400. doi:10.1016/j.gendis.2020.08.013
[21] Suryana KD, Simadibrata M, Renaldi K. Impact of COVID-19 on the Gut: A Review of the Manifestations, Pathology, Management, and Challenges. Acta Med Indones. 2021;53(1):96-104.
[22] Yeoh YK, Zuo T, Lui GC, et al. Gut microbiota composition reflects disease severity and dysfunctional immune responses in patients with COVID-19. Gut. 2021;70(4):698-706. doi:10.1136/gutjnl-2020-323020
[23] Giannos P, Prokopidis K. Gut dysbiosis and long COVID-19: Feeling gutted [published online ahead of print, 2022 Feb 28]. J Med Virol. 2022;10.1002/jmv.27684. doi:10.1002/jmv.27684
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[25] Ng SC, Peng Y, Zhang L, et al. Gut microbiota composition is associated with SARS-CoV-2 vaccine immunogenicity and adverse events [published online ahead of print, 2022 Feb 9]. Gut. 2022;gutjnl-2021-326563. doi:10.1136/gutjnl-2021-326563
