Strengthening the bowels for a good immune system

In the Western world the occurrence of infectious diseases has fallen dramatically due to improved hygiene and vaccines and antibiotics. We started relying on pharmaceuticals, but in doing so we forgot our responsibility to strengthen the immune system. We were reminded of this, however, by the latest epidemic, which impacted mainly more vulnerable groups with weakened immune systems.

The bowels play a much more complex and important part than we first thought. They go beyond the primary role of digestion, and in fact play a part in all the body’s systems. In this a special function is performed by gut microbiota, which are formed at birth and with their complex digestive and metabolic functions are closely associated with the immune system. Together with gut epithelial cells the gut microbiota create a protective barrier against pathogenic organisms, they play an active part in the training and functioning of the immune system and trigger anti-inflammatory mechanisms and impede inflammation.

The immune system is an extremely complex system in your body created by a network of immune cells, tissue and protein molecules, through which immune cells communicate. The system’s vital task is to protect against foreign bodies, harmful viruses and bacteria and also to repair damaged tissue (healing wounds), removing the body’s dead cells and also those that are not behaving ‘correctly’ (e.g. cancerous cells).

While the immune system is working optimally, it is unnoticed. When it functions weakly, you are at greater risk of infection, but when it is too active, this can lead to allergies, auto-immune diseases and so forth.

Bowels are the main defensive fortress

The bowels are the primary place for absorption of nutrients in the body, the place where the greatest exchange takes place between the outside world and your insides, and they are constantly exposed to foreign bodies from the environment. For this reason the immune system must always be ‘on the lookout’. At the same time a major part of the immune system’s function is to control our relationship with gut microbiota. For this reason as much as 80% of the immune system is right there, in the bowels. 

Gut microbiota play a key part in the teaching, developing and functioning of the immune system, and in this way provides the principal contribution to balance in the body.

The very construction of the bowels prevents any easy entry into the interior of the body. The path is closed to pathogens by the ‘gut barrier’, which is composed of three layers:

• gut microbiota
• intestinal epithelial cells protected by a layer of mucus
• the immune system mucous membrane. 

Intestinal bacteria are the first line of defence

In creating the first line of defence, gut bacteria perform various roles. First and foremost, by occupying the intestines useful gut microbiota limit the direct access of pathogens to intestinal cells and their entry into the blood stream.

How? Useful and harmful bacteria compete for space and nutrients, and bacteria also produce toxic molecules that prevent the incursion of pathogens. We call this mechanism of protecting the bowels through the direct competing of microorganisms for nutrients and space colonisation resistance. 

The other task of healthy gut microbiota is focused on strengthening and maintaining barrier immunity, whereby the intrusion of microbes and inflammation and damage to tissue are hindered. Moreover in this way it ensures its own safety, since without a firm barrier the immune system can have a destructive effect even on useful microbiota, as happens with inflammatory bowel disease.

In order for this not to happen, the main strategy is to reduce contact between microorganisms and the surface of intestinal cells. This is achieved through a combination of the functioning of intestinal epithelial cells that produce antimicrobial substances and mucus, which limits the contact between gut microbiota and intestinal tissue, and the functioning of ‘local’ immune cells and the creation of IgA antibodies. These cells and antibodies quickly remove microorganisms that have infiltrated through the intestinal wall. In this way the gut microbiota and immune system are separate, but still connected. 

An important part in the intestinal cells producing sufficient mucus is played by short-chain fatty acids, which are produced by intestinal bacteria during the fermentation of carbohydrates from ingested food. 

Short-chain fatty acids enable the maintenance of close contacts between intestinal cells and create an acidic environment that is unfavourable for pathogenic bacteria. Gut microbiota also indirectly contribute to the creation of antimicrobial substances and mucus in intestinal epithelial cells, they balance inflammatory mechanisms and promote the regeneration of intestinal cells. All this is important for maintaining a strong barrier in the bowels, so any change in the microbial composition is reflected in the thickness of the mucous membrane and the integrity of the close contacts between intestinal cells. 

Maintaining a balance between gut microbiota and the host immune system is a continuous process. An unfavourable environment in the bowels and degraded composition of gut microbiota lead to heightened permeability of the intestines and the greater transit of microorganisms and lipopolysaccharides (endotoxins) in the blood, which activates immune responses and inflammatory processes. 

Gut microbiota are immune system teachers

Have you ever asked yourself how the immune system recognises which are harmful bacteria and which it should leave in peace? 

After birth the immune system develops at the same time as gut microbiota. The first, extremely important interaction between gut microbiota and the immune system takes place at birth. Up until birth the gastrointestinal tract of the foetus is supposedly sterile (although more recently it has been determined that this is not completely true), and the first colonisation takes place as the infant passes through the birth canal. 

At this point the infant’s immune system is still undeveloped, so infants are more susceptible to infection, but on the other hand this enables the establishing of microbiota to proceed without any inflammatory reactions. Gut microbiota send signals that promote the normal development and maturing of the intestinal mucous membrane immune system. An immune system of mucous membrane regulated in this efficient way prevents the intrusion of pathogens and ensures immune tolerance for useful microorganisms. 

Gut microbiota influence the functioning of the entire immune system

Another important function of the immune system is to enable communication between remote systems in the body (e.g. the bowel-lungs axis). Communication between the bowels and other organs (e.g. the lungs) flows through the lymph and blood streams. In this way gut microbiota influence not just the local immune system, but also contribute to the immune response at more remote points. 

The effects of gut microbiota and their metabolites contribute to the immune response of other mucous membranes, such as in the lungs. How this takes place is still not precisely known, but it would appear that soluble metabolites of gut microbiota enter the blood stream, and the immune cells at remote points recognise them and respond accordingly. For instance the microbiota of the gastrointestinal tract affect the differentiation of immune system T-cells into Th1, Th2, Th17 and helper T-cells.

This link between bodily systems is also two-way, so through the migration of immune cells and inflammation molecules the lungs can affect the functioning of the bowels.

In all this we should not forget that gut microbiota synthesise certain vitamins, and that the bowels balance the absorption of nutrients. You might have an excellent diet and consume a wide variety of nutritional supplements, but if your bowels are not functioning the way they should, the absorption of nutrients is diminished. 

How to strengthen your immune system

We have recognised that the immune system and microbiota are closely linked. It makes sense therefore to ask at this point, what affects most the composition of gut microbiota, since in this way you can strengthen your immune system. What links them?

The answer to this question is diet. Both the immune system and gut microbiota are very sensitive to the dietary state of the host. The composition and diversity of gut microbiota are strongly influenced by the individual’s diet and lifestyle, and the gut microbiota then control the immune system in a symbiotic relationship. 

Diet is the key modulator of the immune system and gut microbiota

There are a lot of nutrients that affect the immune system. The basis for a good immune system is:

• proteins 
• vitamins D, C, E and other antioxidants 
• zinc and selenium among minerals
• and omega-3-fatty acids. 

All these nutrients play an important part in maintaining the integrity of physical barriers (mucous membranes and skin), the speed of at which immune cells move around the body, the creation of antibodies, the recognition of harmful foreign bodies and the response to them, and they have antioxidant and antimicrobial properties. Any deficiency of vital nutrients weakens the functioning of the immune system and reduces our resistance. 

Meanwhile we should in no way forget about dietary fibre, which is the main fuel for useful intestinal bacteria and is essential for the creation of short-chain fatty acids. Just how important these are for our immune system has been identified in the text above. 

The recipe for a robust immune system?

1. Reduce consumption of heavily processed food, and food to which you are allergic or sensitive, since they burden the immune system, which leaves it less than optimally prepared to combat outside attackers. 
2. Every day have some monounsaturated (e.g. olive oil and avocado) and polyunsaturated fatty acids (such as fish and seeds). 
3. Make sure you have sufficient protein intake from high-quality animal and plant sources. Proteins are the building blocks of every cell in the body, and thus also the building blocks of immune cells, all the enzymes needed for processes and also cytokines – signal molecules that participate in the immune response. 
4. Consume fibre and probiotic food, which can improve the composition of gut microbiota and increase the production of short-chain fatty acids, which is an excellent method of strengthening the immune system through gut microbiota.
5. Make sure that you consume on a daily basis at least four different colours of fruit and vegetables and in this way ensure sufficient intake of antioxidants. 
6. Of course diet is not the only way to support your immune system. Make sure you have hygienic sleeping arrangements, pursue sports actively and balance your daily stress with relaxation techniques (e.g. meditation, breathing techniques and yoga). 

How Donat helps strengthen the immune system 

Donat natural mineral water, with its unique mineral composition, is clinically proven to help regulate digestion and improve well-being. By drinking half a litre of Donat a day, your digestion will improve in a completely natural way and your body will be able to absorb the nutrients that we get from a healthy diet and that are important for boosting the immune system. As part of a programme to support your digestive system, you can drink Donat continuously and in the long term:

The recipe for a robust immune system?

1. Reduce consumption of heavily processed food, and food to which you are allergic or sensitive, since they burden the immune system, which leaves it less than optimally prepared to combat outside attackers. 
2. Every day have some monounsaturated (e.g. olive oil and avocado) and polyunsaturated fatty acids (such as fish and seeds). 
3. Make sure you have sufficient protein intake from high-quality animal and plant sources. Proteins are the building blocks of every cell in the body, and thus also the building blocks of immune cells, all the enzymes needed for processes and also cytokines – signal molecules that participate in the immune response. 
4. Consume fibre and probiotic food, which can improve the composition of gut microbiota and increase the production of short-chain fatty acids, which is an excellent method of strengthening the immune system through gut microbiota.
5. Make sure that you consume on a daily basis at least four different colours of fruit and vegetables and in this way ensure sufficient intake of antioxidants. 
6. Of course diet is not the only way to support your immune system. Make sure you have hygienic sleeping arrangements, pursue sports actively and balance your daily stress with relaxation techniques (e.g. meditation, breathing techniques and yoga). 

How Donat helps strengthen the immune system 

Donat natural mineral water, with its unique mineral composition, is clinically proven to help regulate digestion and improve well-being. By drinking half a litre of Donat a day, your digestion will improve in a completely natural way and your body will be able to absorb the nutrients that we get from a healthy diet and that are important for boosting the immune system. As part of a programme to support your digestive system, you can drink Donat continuously and in the long term:

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Iacob S, Iacob DG, Luminos LM. Intestinal Microbiota as a Host Defense Mechanism to Infectious Threats. Front Microbiol. 2019 Jan 23;9:3328. doi: 10.3389/fmicb.2018.03328. PMID: 30761120; PMCID: PMC6362409. 

Lo BC, Chen GY, Núñez G, Caruso R. Gut microbiota and systemic immunity in health and disease. Int Immunol. 2021 Mar 31;33(4):197-209. doi: 10.1093/intimm/dxaa079. PMID: 33367688; PMCID: PMC8011437.

Yoo, Ji Youn, Maureen Groer, Samia Valeria Ozorio Dutra, Anujit Sarkar, and Daniel Ian McSkimming. 2020. “Gut Microbiota and Immune System Interactions” Microorganisms 8, no. 10: 1587. https://doi.org/10.3390/microorganisms8101587
Iddir, Mohammed, Alex Brito, Giulia Dingeo, Sofia Sosa Fernandez Del Campo, Hanen Samouda, Michael R. La Frano, and Torsten Bohn. 2020. “Strengthening the Immune System and Reducing Inflammation and Oxidative Stress through Diet and Nutrition: Considerations during the COVID-19 Crisis” Nutrients 12, no. 6: 1562. https://doi.org/10.3390/nu12061562