Why Gut Health is Vital for Immunity: A Comprehensive Guide

Your gut lining, from head to tail, contributes to a whopping 70-80% of your immune system. So, one of the most important things you can do to power your immunity and maintain a healthy body and mind is to look after your digestive health.

You have a collection of gut microbiota as unique to you as your fingerprints. It includes at least 1,000 different species of bacteria, good and bad, with more than 3 million genes, weighing up to 2kg. And some experts now consider this colony of microbiota to be an organ in its own right.

As well as safeguarding immunity, these fantastic microorganisms perform many functions that are crucial to your health like aiding digestion, absorbing nutrients, vitamin production, protection from harmful microbes and maintaining gut integrity.

Healthy microbiota isn't just about balanced gut bacteria; our digestive tract houses fungi and viruses too. When balanced correctly, they all help to protect you from acute illness and chronic disease. It doesn't take much to upset the balance either, so it's essential to be aware of how you are feeding and fertilising your gut bacteria.

A wholesome, fresh food diet and other healthy lifestyle activities cultivate fertile soil for your gut bacteria to thrive. Poor food and lifestyle choices have the opposite effect leading to digestive issues, toxicity, inflammation and illness. Without gut homeostasis, more harmful microbial strains increase, creating a two-fold problem.

Firstly, your gut health suffers, impeding digestion, increasing toxins, causing intestinal inflammation and malabsorption of nutrients – not good for your immunity and wellbeing.

Secondly, this causes weakening of the mucosal lining and tight junctions of the gastrointestinal tract (GI tract), allowing toxic compounds to leak into your bloodstream and body where they are not supposed to be. The result is systemic inflammation.

All this leaves you more susceptible to bacterial and viral infection, and at an increased risk of allergies, arthritis, autoimmune diseases such as Hashimoto's and chronic fatigue, mood disorders, dementia and Alzheimer's. It can also lead to obesity and other chronic diseases, including diabetes, cancer and heart disease.

Never underestimate the importance of your gut health. Look after it, and it will look after you!

70–80% of your immunity stems from your gut which houses immune cells. Your intestinal microbiota assimilates anything that comes into your digestive tract, working mutually with your immune system to modify your metabolism, immunity and infection response. 

From the moment you are born, your innate immune system and microbiota work synergistically and develop together, promoting a finely tuned immune response that builds your resilience to pathogens, protecting you from infection and disease. 

Metabolites are small molecules that drive significant biological activities like energy conversion, cell signalling and oxygenation. Gut microbiota generates a considerable amount of these.

Your immune system monitors these metabolites and adjusts physiological processes accordingly. 

Things start to unravel when the delicate microbial balance is disrupted, for example via poor diet or medication, causing an overgrowth of harmful microbes (known as dysbiosis).

This disturbs metabolite production, and significantly impacts immune cell signalling and messaging to tissues and organs. 

Furthermore, dysbiosis can lead to a weakening of the gut wall, allowing harmful endotoxins and foreign compounds to leak into your bloodstream, causing disease.

As time goes on, you might experience weak immunity, increased susceptibility to infection, systemic inflammation, obesity, chronic illness and disease and organ dysfunction.

Persistent low-level systemic inflammation is linked to an increased risk of chronic diseases such as type 2 diabetes, metabolic syndrome, cardiovascular disease, cancer, Alzheimer’s and depression. 

As mentioned above, disruption to the intricate balance of healthy microbiota can lead to impaired immune signalling and cause a weakening of the tight junctions in the gut lining (known as leaky gut).

These junctions are essential for controlling what is allowed into your bloodstream (nutrients) and what is not (toxins). If these junctions loosen up, it opens the flood gates for harmful compounds to leak out of your gut and into your body.

Once toxins start circulating, it triggers an immune response causing inflammation. Acute inflammation is a natural immune response designed to control infection.

But if nothing is done to fix the problem, the immune system keeps the inflammation going and it becomes chronic. Consequently, serious health issues develop over time.

Autoimmunity is when your immune system becomes confused and mistakenly attacks your body. Leaky gut can also be a precursor to autoimmune diseases including lupus, rheumatoid arthritis, psoriasis and Hashimoto’s.

A healthy gut ensures you get maximum nutrient absorption from your diet, keeping your body functioning optimally and your immunity strong. Research shows that poor nourishment and deficiencies in B vitamins, vitamins A, C, D and E as well as zinc, selenium iron, copper and folate can impair the immune response.

Without the antioxidants and nutritional value they provide, you’re more susceptible to infection of all kinds.

Malabsorption leads to malnutrition, and it’s not uncommon for someone suffering from obesity to be malnourished. Without the right balance of gut microbes, you can feel fatigued as you are unable to get enough energy from your food.

Immune activities require a lot of energy; without enough, your immunity suffers.

Prolonged stress and depression can weaken your immune system, making you more prone to acute illness like colds and coughs and also chronic disease. 

Unlike any other organs in your body, both your brain and gut have their own nervous system, and the gut is often referred to as the second brain or gut-brain axis.

Your microbiota produces neurotransmitters and hormones associated with mood and stress, much more than your brain. For example, around 90% of your serotonin production, the ‘feel-good’ neurotransmitter and chemical messenger associated with depression, occurs in your gut. 

Your brain and gut use the vagus nerve to communicate with each other and send signals. Dysbiosis, leaky gut, IBS, IBD and other digestive disturbance can reduce vagus nerve function. 

It can turn into a vicious cycle as gut inflammation leads to stress, anxiety and depression, and these conditions cause an overgrowth of more harmful bacteria (dysbiosis). 

So, as well as managing stress levels and looking after your mental health directly, your gut must be balanced for a happy brain.

Although less is known about it, there is also talk of a gut-lung axis (GLA) and how the crosstalk between your gut and lungs can maintain and shape your immune response, changing the course of respiratory diseases. 

Like the gut-brain axis, one affects the other, with viral respiratory infections disturbing the gut microbiota and vice versa.

Researchers acknowledge that balanced bacteria are essential to maintain the intense dialogue between the gut and lungs, improving resilience to acute lung infections (Covid), COPD, asthma and cystic fibrosis. 

Researchers also recognise that gut microbiota diversity and the role it plays in immunity can diminish in old age and that the elderly are more susceptible to Covid-19 fatality.

Eating to improve this is essential as part of a Covid-19 prevention plan, certainly in older and immune-compromised people.

However, considering how prevalent impaired gut function is (ask a nutritional therapist), it seems like this is a good action plan for anyone wishing to protect themselves against coronavirus.

A poor diet, low in nutrients and high in processed foods causes inflammation as junk foods contain trans fats, sugar, unhealthy oils, excessive salt, refined carbohydrates and other harmful ingredients. Eating like this is damaging to your gut microbiota. 

So, there’s no getting around it – if you want to be well and encourage good gut health, you have to nourish yourself with proper nutrition.

Sure, we all like to enjoy life and do a little bit of what’s not good for us now and then – but the trick is to strike a balance and eat real, nutritious, non processed, non-junk, non-pre-prepared, non-takeaway food most of the time. 

Think of it in terms of percentage – for at least 80% of the time, eat wholesome, nutritious foods. Your brain, body, mind and gut eat up all the good stuff and love it.

The best diet for you and your gut health is a fibre-rich and diverse array of brightly coloured and green vegetables and fruit. The more varied, the more you encourage a thriving assortment of gut microbiota.

Added to this, eat whole grains (brown bread, pasta, rice as opposed to white – non-gluten if you prefer), healthy protein (beans, legumes, fish, lean meat), healthy fats (avocados, nuts, seeds, olive oil, coconut oil), and plenty of fresh herbs and spices.

Avoid sugar as much as possible, and stay hydrated. This will provide a solid foundation for all your gut microbiota to thrive.

It’s also essential to include pre and probiotic foods daily which encourages new gut bacteria and fortifies the good stuff that’s already there.

It’s fair to say that once you start eating in this way for the majority of the time, you’ll begin to crave more of what’s right for you and less of what’s bad. It may be hard to imagine, but you’d be surprised at how your taste buds and needs will naturally change over time.

It’s not always appropriate to take probiotics, as depending on the gut issues you have, they may need to be addressed first and to rest and repair before the probiotics can have any real impact.

Probiotics can also exacerbate some gut conditions, so if you have a significant problem, it’s best to seek the advice of a nutritional therapist, naturopath or functional medicine practitioner to find out what’s really going on and take the best course of action. 

That said, for the rest of us, taking probiotics can be very beneficial for improving gut health. But it’s not just about taking probiotics; there are other aspects to maintaining the right environment for a healthy balance of microbiota.

Progurt is a supplement range that covers many of these, from cultivating a healthy PH and electrolyte balance to improving nutrient flow. 

To find out more about creating the right gut environment and other useful supplements, read this. 

Poor mental health takes its toll on your gut health and immunity. As previously mentioned, you must have a healthy balance of gut microbiota for your gut-brain axis to work effectively. Added to which, stress, anxiety and depression can negatively affect this, so it’s a double-edged sword. 

Taking the time to focus on your mental and emotional wellbeing is essential for the health of both your body and brain.

Research supports the use of stress-reducing interventions for improving gastrointestinal symptoms, including IBS. These include the practice of mindfulness, meditation and yoga as well as hypnosis, cognitive behavioural therapy and relaxation techniques like deep breathing. 

If you regularly struggle with stress or anxiety, find ways to alleviate the strain. This could be any of the above or simple things like being in nature, spending quality time with friends and loved ones, journaling or writing a daily gratitude diary, finding a hobby, getting involved in your community, and exercising. 

The list goes on, but find the most effective forms of stress relief for you. This article might help. 

There is also a sleep-gut connection, and one affects the other. When your circadian rhythm becomes disrupted through poor sleep, it can disturb your gut microbiota.

Aim for seven to eight hours of undisturbed sleep per night.

We literally can’t survive without water, and our bodies need it for every single thing from cell, organ and brain function, to joint lubrication and oxygen transportation. 

Your gut also needs adequate hydration to move food through your intestines easily. Without it, you can become constipated, food and toxins build-up in your GI tract, and your delicate microbial balance suffers.

Water helps food breakdown, creates saliva which aids digestion, hydrates the mucosal lining of your gut and softens stools making them easier to pass. 

Make sure you stay hydrated, preferably with water but herbal teas also count. Read here for some helpful hydration tips. 

If you want your gut microbiota to thrive, it’s vital to swerve non-prescription medication as much as possible and seek natural alternatives. Any drugs can significantly affect your gut health.

For example, NSAIDs (non-steroidal anti-inflammatory drugs) such as Nurofen and ibuprofen, are known to impact the diversity of gut microbiome severely. They can cause leaky gut and are responsible for over 50% of bleeding stomach ulcers. 

Antibiotics are also well known for destroying healthy gut bacteria, inhibiting our immunity and ability to fight infection. Even for a healthy person, it can also take up to a year for gut microbiome to recover post-antibiotic use.

Researchers fear that some of these harmful changes could be permanent.

Too much vigorous exercise can be harmful to your gut microbes, but regular moderate exercise and movement can help to shift undigested food through your GI tract.

Make sure you get up and move at frequent intervals throughout your day.

As you can see, your gut health impacts your immunity in several ways. If you want to stay as healthy as possible, reducing your risk of acute infections and chronic disease, you have to nurture and cultivate a diverse and robust range of gut microbiota.

It isn’t just about gut bacteria – a finely-tuned balance of bacteria, viruses and fungi are what’s needed, and they all need to be protected. 

Have you been living with digestive issues for some time, or are you concerned that you have serious gut health issues? An accredited nutritional therapist, naturopath or functional medicine practitioner can give you the best advice and create an achievable, tailor-made plan to suit your needs.

If necessary, they can also provide the most up to date and accurate testing to help decipher what is really going on with you. 

Written by Rebecca Rychlik, Nutritional Therapist and Homeopath. Follow Rebecca on Instagram, Facebook and Medium, @rebeccabitesback.

Water for Health Ltd began trading in 2007 with the goal of positively affecting the lives of many. We still retain that mission because we believe that proper hydration and nutrition can make a massive difference to people’s health and quality of life. Click here to find out more.