How to Support the “Front Line” of Our Immune System - the Mucous Membrane

 What you will learn in this article:

• What role mucosa plays in your immunity.
• How you can support your immunity (right now).
• What is the link between sleepies (rheum from the eyes) and your immune system.
• What to serve yourself on your autumn plate to support the immune system.

Immunity

There is no doubt that your body wages many wars on a daily basis in which it protects you against various invasions of bacteria, viruses, yeast, or parasites. One piece of evidence is rheum from the eyes, for example (how? you will read your way to the answer later).

Immune cells as well as friendly microorganisms heroically fight such unwelcome guests. Armies of lactobacilli, bifidobacteria, and some friendly serotypes of E. coli are at your disposal!

If you like to engage your imagination, you can picture your immune system as 3 defence lines.

• First line - skin and mucous membranes.
• Second line - innate immunity.
• Third line - adaptive (acquired) immunity.

As foreshadowed by the title of this article, I will focus only on the first defence line, mainly on mucous membranes.

The role of mucosas, microbiome, and immunity

From the point of view of distribution of protective immune cells and production of immunoglobulins (antibodies), the mucosal immune system is by far the largest constituent of the entire immune system. Personally, I think that calling the mucosal immune system the “front line” of our immunity is completely justified. For example: Has somebody sneezed on you? It is possible that at this very moment, there is a bug travelling to you in a microdrop. But don’t worry. In the front line of defence preventing it from entering your body is precisely the skin and mucosas. 

And what constitutes the mucosal system? Mucosas cover and protect for example the oral cavity, nasal cavity, or the intestines. Additionally, every one of us is the proud owner of vaginal and the mucosal lining of the eye.

The skin as well as all the mucous membranes are inhabited by microbiomes, and each has its own, unique one. These microbiomes communicate with one another, murmuring about what is going on. “Attention, I report that there are some suspicious visitors in the nasal cavity, send reinforcements, please.”

The following section is intended as a small signpost that will tell you in which direction you can turn your attention if you wish to strengthen the defence in the front line of your immune system.

1. Nasal mucosa and nasal microbiome

Imagine I didn’t mention the nasal microbiome in at least one article! We have already talked about the vaginal microbiome, oral microbiome, and dermal microbiome, and the nasal microbiome definitely deserves to be mentioned as well.

What role does the nasal microbiome play in the functioning of your immunity?
The nose is an important part of the mucosal immunity (1). The nasal microbiome has a nose for unwelcome bacteria (sorry, this pun was irresistible) and is very often helpful in preventing some types of infections. Studies have shown that it contains certain kinds of microbiota good at fighting infections (2).

Breathing:
By breathing through your nose, you help to oxygenate your nasal microbiome, thus making life more pleasant for its inhabitants. A happy, properly oxygenated nasal microbiome can function better and more effectively as a nose “filter” of potential intruders that could attack you and make you sick. 

I appreciate that breathing through the nose is challenging for some people. The reason for this can be a deviated septum, for instance. However, the best way to expand the cavity is precisely by breathing through the nose. Thanks to their plasticity, cavities can be shaped, to a certain extent. This will obviously not happen overnight. As with everything, here too any possible improvement will show after some time.

2. The conjunctiva - the mucosa of the eye

What role does the eye mucosa play in the functioning of your immunity?

One of the tangible proofs that your body defends you from undesirable bacterial marauders is right before your eyes. Sleepies (or rheum). Sleepies are partly the residues of the nightly “combat” - the fight between your organism and foreign bodies that attempt to enter your body. They are typically a combination of dead cells of the eye mucosa, crystals formed by the evaporation of tears, dead bacteria, pollen, and dust.

The eyes are said to be the window to the soul. Besides that, they are also a gateway. A gateway into your body through which a number of bacteria and viruses can attack you. And it is often ourselves who bring the bugs there. One small Australian study found that, on average, the observed individuals touched their face 23 times in one hour (3), while some other studies report much higher numbers (4). A harmless rubbing of the eyes of a scratch on the nose is one of the ways in which you can inadvertently weaken your body, bringing it bacteria and viruses that your immunity then has to deal with. It is no coincidence that people who work with dangerous substances are equipped with safety goggles. These help them reduce the risk of contact with bacteria and viruses. 

3. Intestinal mucosa and gut microbiome

What role does the gut microbiome play in the functioning of your immunity?

A mucosal barrier is found in the intestines as well, and its inhabitant is none other than the gut microbiome. The gut microbiome is constantly in contact with all the other microbiomes of our body. Its health and functionality has therefore a significant impact on the microbiomes that inhabit other mucosas and on their ability to protect us against unwelcome visitors. If our goal is an overall support of the immune system, then supporting the health of our gut microbiome and the quality of the intestinal mucosa is in our own interest.

Support the health of your gut microbiome

• Quality foods rich in probiotics - fermented foods.

The benefits of fermented foods were known to our ancestors and nowadays a number of scientific studies prove their positive effect on our body. It was shown that a diet rich in fermented foods increases the diversity of the gut microbiome and improves the function of the immune system (5).

What should the daily dose be?

If you are like me and immediately asked yourself what daily dose would lead to the maximisation of benefits, I offer you the answer right away.

Experiment and start gradually. If you would like to know specific data, I can serve you a 2021 Stanford study which came up with the number 6. A daily portion of six servings of fermented foods brought great results in increasing microbiota diversity and decreasing inflammation (5).

So is 6 the magical number we are looking for? No, it’s not. For some individuals, incorporating this dose of fermented foods from one day to the next could be a huge shock for their microbiome. Start slowly, please. This goes especially for people struggling with intestinal ailments (such as SIBO - bacterial overgrowth) or are fighting a yeast infection.

The following section brings you a small portion of inspiration in which foods rich in probiotics can help you support your gut microbiome.

• Fermented cabbage (sauerkraut)

The best is homemade, of course. If you have to buy it in a shop, however, there are a few things to keep in mind:

Reach for refrigerated cabbage that was not heat treated. Simply avoid cabbage that is sterilised or pasteurised.

Have a look at the ingredients. Honest sauerkraut is a true minimalist and it only needs cabbage and salt for its sour happiness. Caraway and mustard seeds are also OK. And that’s enough. If there is vinagre, sodium benzoate, sodium hydrogen sulphate, or another preservative, this is a hint that the cabbage you are holding in your hand may have been pasteurised.

• Kombucha

Kombucha is alive! And so, similarly as with sauerkraut, choose refrigerated kombucha. This drink is traditionally made from green or black tea, so one of these teas must be on the ingredients list. If it says made with tea flavouring, extract, or essence instead, perhaps you should put the bottle back and keep browsing. As for sugar, it is added to kombucha as food for friendly bacteria. But even though its presence is necessary, it should not dominate the list of ingredients. Opt for kombucha with less that 10g sugar / portion.

• Plain yoghurt with live cultures

How can you tell the quality of yoghurt? Take a look at the label before placing it in your basket. Choose yoghurt that contains live active cultures such as the probiotic strains of Bifidobacteria and Lactobacillus.

In conclusion

Right. So these are three fields in which small and big battles are fought day and night. In autumn and the coming winter, the question of immunity is especially topical. In our everyday activities, we make mini-decisions through which we can (inadvertently) make our body’s immune fight more difficult, but also easier.

Is the flu wreaking havoc around you? For starters, you can remember a small mnemonic: Nose, eyes, gut.

• Breathe through the nose.
• Minimise touching the area around your eyes.
• Pamper your gut microbiome. 

Bibliography:

1. Kiyono, H., & Fukuyama, S. (2004). Nalt- versus peyer's-patch-mediated mucosal immunity. Nature Reviews Immunology, 4(9), 699-710. doi:10.1038/nri1439
2. Belkaid, Y., & Hand, T. (2014). Role of the microbiota in immunity and inflammation. Cell, 157(1), 121-141. doi:10.1016/j.cell.2014.03.011
3. Kwok, Y. L., Gralton, J., & McLaws, M. (2015). Face touching: A frequent habit that has implications for hand hygiene. American Journal of Infection Control, 43(2), 112-114. doi:10.1016/j.ajic.2014.10.015
4. Belkaid, Y., & Hand, T. (2014). Role of the microbiota in immunity and inflammation. Cell, 157(1), 121-141. doi:10.1016/j.cell.2014.03.011
5. Wastyk, H. C., Fragiadakis, G. K., Perelman, D., Dahan, D., Merrill, B. D., Yu, F. B., . . . Sonnenburg, J. L. (2021). Gut-microbiota-targeted diets modulate human immune status. Cell, 184(16). doi:10.1016/j.cell.2021.06.019