Dr Jenna Macciochi smiling at the camera

15 Things You Need to Know About Immune Health and Your Gut with Dr Jenna Macciochi

Did you know that approximately 70% of your immune system resides within your gut? This includes immune cells, tissues and organs, all located along the long tube known as the digestive tract. This means that the gut and immune system are intricately connected, forming a dynamic partnership that plays a pivotal role in your overall health.

The Gut-Immune Connection 

The gut-associated lymphoid tissue, often abbreviated to GALT, is the home to your gut immune system and is up close and personal with the trillions of microorganisms residing in your digestive tract. Turns out the gut-immune relationship is a pretty big deal when it comes to your health. These microbes, collectively known as the gut microbiome, exert a profound influence on your immune system both locally in the gut and beyond.  

Think all germs are bad with the potential to infect us and make us sick? Think again! For billions of years, humans and microbes have shared an interdependent existence. This means the human immune system has co-evolved alongside the trillions of microbes that inhabit our bodies, with the majority taking up home in our gut.  These helpful, often called friendly microbes, have, over time, fostered a mutually beneficial relationship - known as symbiosis - with our immune system. This means the gut microbes and immune cells mutually benefit from each other's presence and actions. 

Let’s delve into the fascinating link between your immune system and gut

1. Training and educating the immune system 

Our immune system undergoes a significant part of its development just after birth. At birth, it's relatively inexperienced and needs to learn how to discern between harmful and harmless microorganisms. The gut microbiome plays a critical role in training and educating the immune system to differentiate between the harmful and the harmless. This education process is crucial in childhood and continues throughout our lives to prevent unnecessary immune responses like allergies and autoimmunity.

2. Immune tolerance and regulation 

Gut bacteria help regulate the immune system's responses. They can either activate or suppress immune reactions as needed. This balance is critical for responding effectively to infections while preventing chronic inflammation or autoimmune reactions, where the immune system mistakenly attacks the body's own tissues.

3. Digestion of fibre 

You might have heard that fibre is good for us, but did you know that humans rely on our gut microbes to break down fibre because our digestive enzymes struggle with this task?  Fibre is the collective term for the complex carbohydrates found in fruits, vegetables, herbs and spices, nuts and seeds, whole grains and legumes. Lucky for us, our gut bacteria possess enzymes capable of breaking down these complex carbs, allowing us to reap their health benefits. In turn, fermentation of fibre by gut microbes promotes the growth of beneficial bacteria in the gut, which helps maintain a balanced and healthy gut microbiome.

4. Production of important ‘metabolites’ like SCFA 

When your gut microbiota break down fibre they produce metabolites. These might be their metabolic waste products, but they include crucial nutrients like essential amino acids, certain vitamins and special immune-nourishing messenger compounds called short-chain fatty acids (SCFAs). Collectively these play a very important role in resourcing our immune system with all the nutrients it needs to work optimally. Consider this your own personalised pharmacy.

5. Supporting the production of immune factors 

Some gut bacteria contribute to the production of antibodies and other immune factors crucial for combatting infections. For example, certain species of bacteria in the gut support the production of immunoglobulin A (IgA), an antibody that helps protect the mucosal surfaces of the gut.

6. Maintaining gut barrier function and mucus layer 

A healthy gut barrier is essential for preventing harmful microorganisms from entering the bloodstream. The gut microbiota helps sustain the gut barrier’s integrity by promoting the production of mucus and other protective factors like SCFA - the primary energy source for the intestine. This fortifies the gut barrier, helping to keep any bad stuff in your gut from passing through into your body.

7. Supporting immune tolerance 

The gut microbiome plays a pivotal role in promoting immune tolerance - the ability of the immune system to be balanced. It does this by promoting the production of regulatory T cells (Tregs), a type of immune cell central to immune tolerance. Tregs help suppress excessive immune responses, keeping the immune system in check.

8. Occupying Ecological Niches 

The gut is a diverse ecosystem where various microbes coexist, including bacteria, viruses, fungi, and archaea. These beneficial microbes occupy specific ecological niches in the gut. These niches leave less space available for potentially harmful invaders.

9. Resource Competition 

Microbes in the gut compete with harmful bacteria for essential nutrients and resources. Beneficial bacteria are adept at efficiently utilising these resources, leaving fewer nutrients available for pathogenic microbes. This competition can limit infections caused by harmful species. 

Have I convinced you? The state of your gut health significantly affects how your immune system responds to threats. Now remember, what happens in the gut, doesn’t stay in the gut, but this relationship extends far beyond the confines of the digestive system, influencing the immune system throughout the entire bodyThis wide-reaching influence has profound implications for various aspects of our health. Research indicates that an imbalanced gut microbiome can be associated with a whole range of symptoms, diseases and conditions of poor health including increased risk of infection, something we all need to be aware of at this time of year.  

How to support your immune system 

As the autumn leaves fall and winter's chill approaches, the prevalence of viruses causing seasonal coughs, colds, and flu increases. It's time to pay extra attention to your immune health. While many people associate this with things like vitamins and supplements, they often overlook the fact that the gut also plays a crucial role in the immune health equation. So, how can you ensure you have the best mix of gut microbes to bolster your immune health? To support the community of beneficial gut bacteria and a robust immune system, there are lots of small improvements to our diet and lifestyle that we can implement.

6 quick tips to nourish your gut and support your immune system

1. Probiotics 

Incorporate fermented foods that contain live microbes like yoghurt, kefir, sauerkraut, and kimchi into your diet. Trying a probiotic supplement is also an option to bolster your own gut microbiome. Many strains have been found to exert immune-modulating effects as they make their journey through the gut. 

2. Prebiotic Fibre 

Consume plenty of fibre from fruits, vegetables, nuts and seeds, beans and pulses and whole grains. Don’t forget the herbs and species count too, even the dried ones. More is better and opt for plant diversity when you can. This fibre serves as nourishment for beneficial gut bacteria, promoting their growth and diversity and enabling them to exert all their immune-nourishing benefits.

3. Vitamin D

Optimize vitamin D levels as this hormone plays a crucial role in immune function and your ability to keep winter colds at bay. You can get it from sunlight exposure, fortified foods, or supplements as recommended in the UK between October and April.

4. Stay Hydrated

Proper hydration supports mucosal barriers in the gut, helping them act as a barrier to prevent pathogens from entering our bodies.

5. Avoid excessive use of antibiotics

As they can disrupt the gut microbiome. Instead, work with your healthcare provider to find alternative treatments when appropriate.  

6. Lifestyle factors 

And finally, just remember that our gut health isn't solely determined by our dietary choices; it's also influenced by other lifestyle factors like physical activity, the quality of our sleep and stress is a known disruptor of gut health and immune function.  

In summary 

Your gut and immune system are partners in maintaining your overall health, especially as you prepare for the autumn and winter months. Understanding and nurturing their connection is essential, especially as you prepare for the autumn and winter months. By nurturing your gut microbiota with probiotics, prebiotic fibre, and a balanced diet, you can empower your immune system to face seasonal challenges head-on. Additionally, prioritising gut health through lifestyle changes and stress management can help you stay resilient and healthy throughout the year.