Gut Health & The Immune System: What’s The Link?

Gut Health & The Immune System: What’s The Link?

Did you know that over 70% of our immune system is located in our gut?

The gut is home to a diverse community of trillions bacteria, viruses and fungi, known as the gut microbiome and it’s directly influenced by your diet and lifestyle including the environment you live in and your stress levels, as well as genetics, gender and age. The microbes present in our guts regulate a number processes in our bodies, including our immune system.

Do you want to support your gut health and strengthen your immune system? If you’re interested in improving your nutrition and your wellbeing, head to Consultations to see how I can help you start your journey to the healthiest version of yourself today!

How does gut health affect our immune system?

Research into how implicated our gut microbiomes are in our overall health is in relatively early stages compared to a lot of other scientific research. In the last few years, we have gained a better understanding of the role of our gut microbiomes on weight and energy levels throughout the day but interestingly also, how it affects our immune system.

What (and where) is the immune system?

 When we talk about our immune systems, it is almost as if it is a separate organ in itself, but in fact, the immune system is spread throughout our bodies. The organs that make up the immune system are primarily our thymus and bone marrow, as well as lymph nodes, skin, tonsils, adenoids, liver, spleen and lymph arteries.

It is said that 70-80% of our immune system is located in the gut. When we hear this fact, it refers to the existence of immune cells in our intestines, such as differentiated epithelial cells (enterocytes, Paneth cells, goblet cells) and gut resident-immune cells (T cells, B cells, dendritic cells, innate lymphoid cells) and several more. 

What’s the link with gut health?

The gut contains a thin wall that works as a barrier between what stays in the intestine (our gut bacteria) and other tissues in the body, controlling what passes into the bloodstream. This is known as the intestinal epithelial layer, and is protected by a layer of mucus as a further defence called our intestinal mucosa. There is an intricate interplay between our epithelial layer, intestinal mucosa and our gut bacteria, making up the three main areas in the gut and the main hurdles that pathogens need to overcome to cause an infection in the gastrointestinal tract. 

Factors that disturb the community and balance of bacteria and their function, such as the use of antibiotics, give space to pathogens (or harmful mechanisms) to colonise and grow in our guts. Diet, stress, antibiotics and some drug treatment can alter the structure of our microbiota, leading to an imbalance of bacteria known as dysbiosis. This can activate our immune cells and creating an inflammatory response. Over time, this low-grade inflammation increases our susceptibility to infections and can damage the integrity of our gut linings.

What does this mean for us?

Overall, this means it’s really important to maintain a ‘good’ balance of bacteria in our guts, with more ‘good’ than ‘bad’ bacteria and we know that diet is one of the key determinants of this. This means therefore, that nutrition is a really key determinant of immune function.

How does this relate to autoimmune conditions?

Three factors are at play when it comes to autoimmune conditions: genes, the immune system and the environment a person lives in.  

Research is increasingly showing the involvement of the gut microbiome in autoimmune conditions such as rheumatoid arthritis, lupus, type 1 diabetes, eczema, inflammatory bowel disease (IBD) and so on, but we are not at the stage where this is fully understood yet. 

We do know though, that if a person’s gut microbiome becomes unbalanced and contains more harmful bacteria than good bacteria, and our immune system is triggered as explained above, this can lead to flare ups in these conditions and worsening of symptoms.

How can we look after our gut health and immune system health?

Looking after our guts and our immune health are achieved the same way, and this is through a multi-faceted approach (meaning there are a multitude of factors we need to be working on).

It’s important to note that nutrition looks different for everyone, which is why I take a personalised approach with all of my 1:1 clients and tailor each nutrition plan to their unique needs and goals.

30 Plant Points A Week

Of course, our diet is an important factor, and the best way to achieve this is by eating a variety of different plants, such as fruits, vegetables, herbs, spices, beans, pulses and so on. Even coffee and tea count as plant points! We should be aiming for at least 30 different sources every week, and bonus points for any fermented foods such as kimchi, sauerkraut, tofu, tempeh, natto, kefir and kombucha. You ay want to check out my blog post on What Are Plant Points + How To Get 30 Plants A Week to learn more about this!

Fermented foods

Fermented foods contain live bacteria that help contribute to a healthy balance of gut bacteria, and other plant sources contain fibre and polyphenols (antioxidants) that help feed the good bacteria in our guts.

Lifestyle: stress & sleep

Stress and sleep are two other really important factors that if you are neglecting, a healthy diet likely cannot fix! Stress is an inflammatory response that impacts the speed at which food moves through our digestive system, changes the permeability of our protective intestinal mucosa layer, impacts our hormone secretion and vitamin absorption. Our gut health is also heavily impacted by the amount and quality of sleep we are getting and vice versa. Poor sleep also negatively impacts quantities of ‘good bacteria’ in our guts.

Effective stress management strategies look different for everyone, but some things to try could include exercise (low intensity) including walking, yoga and meditation, breathing exercises like box breathing and we should also be aiming for a consistent bedtime each day and 8 hours of sleep per night!


Whilst we continue to understand more about this subject as research is ongoing, what we do know so far implicates the immune system, our susceptibility to infections and developing autoimmune conditions really significantly in our gut microbiomes. Ultimately it’s essential to support our gut health in order to look after our immune system.


This is just a small insight into the types of things I discuss with my 1:1 clients. If you’re looking to optimise your nutrition, transform your health and elevate your quality of life, please get in contact via Consultations or book a FREE 15-minute call and let’s chat about how I can help.  

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This blog post was written by Jasmine Bliss, a Registered Associate Nutritionist (ANutr). 

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