The Gut Isn’t Just About Digestion

When we think about the gut we might just think about its role in digesting and absorbing food. For the most part, we may be unaware of this process as it takes place without our conscious control.

It’s only when we start experiencing symptoms such as the ones common in IBS.  (bloating, constipation diarrhoea and cramping) that we notice that something might going wrong in our gut.

It’s All Connected

What is becoming clear is that what happens in the gut doesn’t just stay in the gut.  We call these connections between these parts of the body ‘axis.  For example, there’s the gut-skin axis, the gut-brain axis and also the gut-lung axis.

So even if there’s no bloating or any other IBS symptoms there is still opportunity to support the gut and there for support the lungs.

The Gut-Lung Axis

From birth we seen a connection between the probiotic bacteria in the gut and the lungs.  For example, modifications of newborns’ diet influences the composition of their lung bacteria.

This can also happen in the opposite direction with the bacteria in the lungs influencing the gut microbiome.

Gut Immunity

The gut bacteria interact with the immune system along the gut wall.  This can influence white blood cells and how the travel from the blood into tissue.

Not only within the gut, but throughout the entire body.

Lung Immunity

We know there is a role to play from birth in how the gut microbiome is colonised. With both c-section births and anti-biotic use increasing the chance of developing lung conditions such as asthma.

The bacteria in the lung play a role in the maturation of lung immunity.  We see that the bacteria first colonising the lungs provide essential signals for local immune cells with long term consequences. 

There are also animal studies which show that antibiotics during a viral infection increase the change of upper respiratory tract infections.  Antibiotics also appear to increases the severity of these infections.

How Does Our Gut Support Our Lungs?

Beyond the immune system regulation that occurs in the gut, we also see the impact of the gut microbiome in the immune system in the lungs.

The gut and the lungs are linked via out lymphatic system.  It’s through this pathway that bacteria or specific metabolites may enter our general circulation and support the immune system.

The most prominent group of these beneficial metabolites are known as Short Chain Fatty Acids (SCFAs).  These are produced as our gut bacteria fermented specific fibres found in food.  Once these compounds travel to the lungs they act as signals to the immune cells and support the immune response.  Additionally, SCFAs support the maturation of immune cells by travelling to the bone marrow.

Immune Support During Viral Infections

Although studies specifically looking at Coronavirus / COVID-19 are lacking, there are studies examining the immune response in mice.  Studies have indicated that antibiotic treatment causes a significantly reduced immune response against influenza viruses.

While at the same time, mice infected with influenza had a better survival rate when fed a diet high in fermentable fibres when compared to mice that were fed a low fibre diet.

The Gut Lining

While we do absorb a vast array of vitamins and mineral from the food we eat other compounds are created.  As mentioned, beneficial compounds called SCFAs are produced during the fermentation of fibre in the large intestine.

This can be seen in a different way to the concept of ‘you are what you eat’.  Perhaps an equally important term is ‘you are what your bacteria ferment’.  Although, this doesn’t roll of the tongue in the same way.

Here we see that the bacteria in the large intestine act as a ‘middleman’.  Taking the fibre from the food that we eat and creating new compounds.  It’s these that support the gut and the systemic immune system.

Which Foods?

Fermentable fibre is also called prebiotic.  Essentially this is the food for the bacteria which is primarily found in vegetables and fruits.

Sources include;

Vegetables
Garlic, leeks, onions, cabbage, artichoke, radish, carrot, cucumber, asparagus, beetroot and sweet potatoes.

Fruits
Tomatoes, apples, berries, bananas and mango

Other
Honey, dark chocolate, coconut flour, flaxseeds, hemp seeds, chia seeds, pumpkin seeds, legumes, quinoa and wild rice.

Prebiotic rich foods to support the gut microbiome

Conclusion

There are certainly many ways to support our immune system. The interaction between our diet, our microbiome and our immune system is one of the most central ones.

While we may all have ideas as to what a ‘healthy diet’ is, I do hope this article has helped to give a clearer idea of what to eat for a happier and healthier immune system


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