Our amazing immune system

by sue

Our amazing immune system

by Sue Kira, Naturopath & Clinical Nutritionist

Introducing the Immune System

Your blood

Main components of the Immune System

The three main types of immune dysfunction

How to support and strengthen the immune system

An analogy (a layman’s guide)

In conclusion…

Introducing the Immune System

This article is about the wonderful protector that is working inside your body right now to protect it against foreign or infectious compounds, such as bacteria, viruses, cancer cells, allergens, and chemicals.

The immune system is one of the most complex systems in your body, consisting primarily of different types of white blood cells that do most of the work, along with help from the lymphatic system and various organs including the liver, spleen, tonsils, adenoids, thymus and appendix. Bone marrow is also involved in the production of the white cells needed by our immune system.

About 80% of the immune system’s activity is in and around the gut, which is why your gut health is so important.

A healthy functioning immune system protects and helps you to stay well, heals wounds, clears allergies, gets rid of toxins and chemicals, fights infections, viruses,  influenza, colds, cancer and more.

But not everyone has a perfect immune system. Some have a hyperactive system known as auto-immune disease, where our immune system attacks healthy cells.

The immune system is extremely complex, so the purpose of this article is to help you understand the basics about how the immune system works, what organs, vessels and cells are involved in the process of protecting us, and what you can do to help support your immune system.

If it turns you on, you could go to university and study immunology for several years and become an immunologist or a scientist and research this fascinating subject.

Your blood

To understand the immune system, it’s useful to understand a little about your blood.

I’ve been looking at blood through microscopes for more than 30 years, initially in a haematology lab, then forensic medicine, and as a naturopath for 27+ years. I actually had my first microscope at the age of 12.

Blood is vital to our respiration, nutrition, excretion, immunity, temperature regulation and haemostasis (clotting).

An average adult of 70kg has about 5 litres of blood (about 7% of the body’s weight) made up of approximately 54% plasma and 46% of cells and fragments.

Within those cells and fragments, red blood cells make up 45% of the total, which leaves 1% for the platelets and the white blood cells. This means that white blood cells, your primary immune fighter, occupy less than 1% of your blood’s overall volume.

Plasma is the fluid that carries it all throughout your body. The primary purpose of red blood cells is to carry oxygen and nutrients, while white blood cells are vital to protect your body, and platelets are the clotting agents. Both red and white cells are produced in the bone marrow.

I find viewing live blood under a powerful microscope fascinating – it’s a window to my clients’ health. For example, dark red blood can indicate too much iron in the system or a lot of oxidation, pinkish blood tells me that there’s probably an excess of fat in the diet. And that’s just from looking at the drop of blood before it goes under the microscope.

In one drop of blood there are millions of red blood cells, which are being made in your body at the rate of two to three million every second. They live for about 120 days and are disposed as new ones get produced.

I also see the live activity of white blood cells – how they move, how many of each type there are, the health of the cells and if they’re on their way out, coming into maturity or moving sluggishly. Each provides an indication of the immune system’s health.

Within the white blood cells are monocytes, lymphocytes (which can be T lymphocyte cells or B lymphocyte cells), neutrophils, basophils, and eosinophils, each with a different job. Elevated numbers of any of these can provide a different indication as to what is happening within the immune system. From these white cells I can see if the body is fighting a bacterial infection, viral infection, allergies or if you are likely to have parasites.

There’s more to it, but this gives you an idea of what we see through a powerful microscope.

Main components of the Immune System

White Blood cells

Immature white blood cells are manufactured in the body by bone marrow, then matured and developed into various types of white blood cells.

They have a much shorter life than red blood cells, about two to three days, but can last up to two weeks if needed for emergencies. Your body is constantly making more to fight infection (it’s happening right now!).

They wait in different places in your body…ready for action.

The Lymphatic System

The lymphatic system is a complex network of vessels, nodes, glands and organs that follows (mirrors) the blood vessels. It’s like a duplicate blood system but instead it carries lymph, which is a colourless fluid carrying white blood cells.

The word ‘lymph’ as part of the word ‘lymphatic’ is derived from the word ‘lymphocytes’ the main white blood cells involved in the immune system.

Lymphoid organs/tissues refer collectively to places in the body that store, produce or process lymphocytes. Lymphoid tissues are typically located at sites that provide a possible route of entry of pathogens (germs) and sites that are liable to infections.

These include the lymph nodes, spleen, thymus, tonsils, adenoids and appendix.

Bone Marrow

All the cells of the immune system, the white blood cells, are initially derived from the bone marrow. They form through a process called haematopoiesis (keep that one up your sleeve for a trivia night).

During haematopoiesis, bone marrow-derived stem cells differentiate into either mature cells of the immune system, or into precursors of cells that migrate out of the bone marrow to continue their maturation elsewhere.

The bone marrow produces B cells, natural killer cells, granulocytes (which collectively are the eosinophils, neutrophils and basophils – so called because they all contain granules), along with immature lymphocytes (all types of white blood cells), in addition to red blood cells and platelets (platelets help us clot our blood when we bleed).


The function of the thymus is to produce mature T cells. Immature white cells called thymocytes leave the bone marrow and migrate into the thymus where they mature and are released into the bloodstream as T cells. (They get the ‘T’ to signify that they come from the Thymus).


The spleen is the immunological filter of the blood and can also be thought of as an immunological coordination hub. It contains B cells, T cells, other white cells and red blood cells. An immune response is initiated when the white cells present the foreign material to the appropriate B or T cell. In the spleen the B cells become activated and produce large quantities of antibodies.

Also, the spleen filters out and destroys old red blood cells. These dead blood cells comprise a large proportion of the waste matter excreted by our bowels and contribute to it being brown in colour, along with excreted bile from the liver and gallbladder.

Lymph Nodes

The lymph nodes function as an immunologic filter for the body fluid called lymph. Lymph nodes are found throughout the body. Composed mostly of white blood cells, the nodes drain toxic fluid from our body via our blood vessels. Our lymphatic system is comprised mainly of lymphatic vessels that follow the entire blood system of vessels (arteries, veins, and capillaries). The nodes are like collection centres along the vessels that collect the rubbish filtered out by the lymph vessels.

The Liver

The liver has thousands of jobs to carry out, but the main immune role is in the clearance of internal and external toxins. Internal, or endogenous, toxins are those made by the body, which are internally made by-products of metabolic processes. External, or exogenous, toxins are those that are externally derived and enter the body via mouth, skin, or inhalation. Many of these toxins are first filtered out of the blood via the lymphatic vessels and lymph nodes, which then pass those toxins on to the liver to conjugate (bind to amino acids) for safe clearance by the urinary tract and bowels.

More about B and T cells

B cells are involved in antibody-mediated immunity i.e. the activation of B cells. On activation with antigens (foreign material) B cells either break down into cells which secrete immunoglobulins (antibodies) capable of binding to a specific type of antigen, or alternatively, form into memory cells.

The memory cells job is to ‘remember’ a foreign substance so that next time it appears, it already knows it is dangerous and aims to get rid of it. It is basically how our immune system can recognise good from bad. Sometimes this system goes awry and creates auto-immunity or allergy activation.

T cells act by direct cell-to-cell contact to protect the body, rather than producing antibodies like the B cells do. T cells bear unique T cell receptor proteins that only recognize specific antigens (foreign matter).

There are three main types of T cells. T helper 1, 2 and 3 cells.

1. T helper 1 cells (Th1) regulate our defence against bacteria, viruses, fungi, and parasites. They also play a role in destroying tumour cells.

2. T helper 2 cells (Th2) promote the production of antibodies.

3. T helper 3 cells (Th3) provide immune control through regulating excess Th1/Th2 activity and are governed predominantly by the gut health, which is why it is said that 80% of our immune system relies on good gut health

These T helper cells regulate themselves by having opposing effects. Whenever we have excess activity of one T helper type, this causes suppression of the other. In this way we can imagine our immune system as a seesaw, with Th1 on one side of the seesaw and Th2 on the other side and in the middle at the balancing point are the Th3 cells, which regulate excess Th1/Th2 activity.

The three main types of immune dysfunction

1.Th2 dominance (excess Th2 with low Th1)

This is associated with allergic disorders (e.g. eczema) and frequent infections, due to a low Th1. Factors that influence and perpetuate an underlying Th2 excess include aging, poor dietary and lifestyle choices, exposure to stress and environmental toxins, which explains why 80% of immune complaints are due to Th2 excess and Th1 deficiency.

2. Th1 dominance (excess Th1 with low Th2)

When overactive, Th1 can attack our own body and cause auto immune diseases, such as rheumatoid arthritis, Hashimoto’s thyroiditis, multiple sclerosis, Crohn’s disease, psoriasis, and some unexplained recurrent miscarriages.

3. Th3 imbalance

Th3 is the regulator of balanced immunity dysfunction. An imbalance of Th3 is commonly caused by overgrowth of unhealthy bacteria in the gut, parasites, or insufficient good bacteria, leading to an imbalance of Th1 and Th2.

This highlights the importance of maintaining a healthy diet, good digestion, and the need for an occasional gut detoxification and repair program to keep your immune system functioning well.

How to support and strengthen the immune system

This information applies to avoid all infections including bacterial, viral, parasitic, fungal and worms.

An infection is just that: an organism that infects your body – the cells of your body.

The sickness and symptoms are not the virus, that’s the immune response to the virus, such as a runny nose, coughing, fever etc. These are some of the body’s responses to remove the infection. It’s like a splinter that has not been removed in your finger. The body wants to eject it, so it creates puss, which is the white blood cells at work to reject it.

Some of the more serious symptoms such as blood through the kidneys are a result of an infection causing the breakdown of the delicate tissues of the kidneys.

Immune dysfunction can be caused by various things including physiological and emotional stress, toxicity, hormonal imbalances, lack of sleep or relaxation, nutrient deficiencies (due to poor diet or poor absorption), insulin resistance e.g. diabetes, hypoglycaemia and also the use of antibiotic, medications, alcohol and drugs.

These can all lead to overgrowth of unfriendly bacteria, yeasts, or parasites in the gut, and poor detoxification of chemicals and toxins in the liver, leading to an imbalance of Th1/Th2.

Suggestions to support your immune system:

Gut Health

It’s widely recognised that 80% of our immune system is in the gut, so good gut health with good microbial biodiversity is super important.

In your gut you need a diverse range of good bacteria and not many ‘bad bugs’ such as parasites, fungi/moulds, pathogenic bacteria or viral particles. There are many probiotics on the market, but not all are created equal, so it’s best to get good advice for the right types for your body.

Gut health is probably the most important aspect to protect your immune system (hence the pic at the top of this article).


A healthy diet is the foundation of a healthy immune system. It’s simply a matter of choosing what is right to put into your body, which means a diet that is nutritious with limited or no processed fats, sugar, salt, tea (herbal teas can be healthy), coffee, alcohol, processed refined foods and many take-away foods.

It’s important to avoid sugar because sugar kills huge numbers of white blood cells. Those white cells are the good guys that fight our infections. We need them all. Consuming a few whole fruits daily is acceptable.

Stay hydrated – drink two litres of purified water daily (or more if exercising). Good hydration allows your body to flush out germs easier and be more efficient to detoxify. Ensure your hydration is not of diuretic nature such as coffee, tea, soft-drink, alcohol, chocolate drinks etc.

I’d like to add that plant foods, and more specifically the fibres they contain, are what our friendly bacteria eat and thrive on. It seems that there’s a good bug type for every type of food fibre. It’s not quite that simplistic, but the more diversity you have in the types of plant foods, the better the diversity of your microbiome. The better the diversity of your microbiome, the better your health and immune function.

Click for more information about an Auto-Immune Diet


In our busy world it sometimes seems difficult to maintain a healthy nutritious diet, which can place enormous strains and stress on the body. Let’s look at stress and how it affects our immune system.

Whether physical, emotional, environmental or from poor food choices, stress uses up nutrients.

Poor nutrition provides insufficient minerals. Insufficient minerals make us more susceptible react to stress. Stress depletes our minerals. And the cycle goes on!

Stress also depletes key vitamins in the same way that minerals do. Our vitamins are co-factors that produce various pathways to create hormones, neurotransmitters, and other things. Stress uses up some vitamins and minerals in abundance, particularly the important B group vitamins, vitamin C, zinc and magnesium – along with others.

Stress can also release the hormones cortisol and adrenalin. Adrenalin creates an alarm-like state that we usually associate with anxiety and nervousness. Prolonged exposure to high levels of cortisol and adrenalin eventually results in abnormal function of the nervous system, resulting in other health conditions, as well as the shutting down of digestive function.

Cortisol protects the body from the effects of stress by inhibiting excess inflammation and tissue damage. The problem is that excess cortisol suppresses the immune system, which can increase the risk of infections and allergies.

Hormonal (metabolic) imbalances

Here’s another potential vicious cycle. Hormonal imbalance can create stress, yet stress can create hormonal imbalance. What comes first – the chicken or the egg?

Thyroid hormones increase during acute stress to aid the ‘fight or flight’ response. However, during long term stress, raised levels of cortisol eventually lead to depleted thyroid hormones resulting in low thyroid activity.

What’s the connection to the immune system?

Hormones from the adrenal glands (cortisol and adrenalin) reduce immune antibody production. Thyroxine (thyroid hormone) increases T cell activation, but when thyroid hormones are low the T cells are suppressed (low). Oestrogen and progesterone can aid an unbalanced immune system, but if the levels of oestrogen and progesterone are unbalanced then the immune system will also be unbalanced.


Your gastrointestinal tract naturally harbours about five hundred different species of bacteria which number in the trillions. We apparently have more bug DNA than human DNA in our body. Fascinating! Although many of these bacteria are essential for health (remember the T3 cells) they can become very toxic if certain bugs start to overgrow and create an imbalance.

This may happen because of poor digestion, antibiotics, gut infection, or stress. We also consume and absorb many toxins from our external environment such as chemicals and heavy metals from the foods we eat, the air we breathe, the water we drink, the chemicals in personal care items, and building materials and furnishings that can release chemicals.

The gut and liver protect the body against disease by eliminating and detoxifying toxic compounds and waste products which can cause inflammation and immune dysfunction.

A gut/liver detoxification program can help correct digestion, normalise gut bacteria flora, repair a damaged gut wall and improve the detoxifying capacity of the liver and kidneys. As these organs start to function better the toxic load on the immune system is reduced thereby allowing Th1 and Th2 to become better balanced.

The importance of a periodic detoxification program is clear. The detox can take many forms, such as an alkaline diet (high plant food focus) over a period of time, various fasting programs (intermittent fasting is proving very successful), saunas (especially far-infra-red saunas) and of course the benefits of exercise.


Exercise can increase your body’s oxygen carrying capacity and improve how you clear toxins via the lungs and skin (sweat). By moving more often we also have greater lymphatic clearance. Unlike the heart, the lymphatic system doesn’t have a pump to move fluids and toxins around the body and requires movement to clear toxins via our lymph vessels. Movement also helps clear toxins via our bowel more efficiently.

If you exercise outdoors you also get the benefit of microbial biodiversity from organisms in the environment. Studies have shown that people who exercise outdoors have a greater diversity in their gut microbes which is proven to be effective to support the immune system.

But many who are into extreme exercise, such as triathlons, marathons and competitive sports at high levels often get sick after extensive training and competing due to being ‘run-down’. We have this expression for a reason.

Overexertion places demands on our body in many ways including depletion of vitamins and minerals because of the high demand, and the inability to consume enough nutrients to cover the extra needs, especially as it’s difficult to ‘eat and run’. Exercise on a full stomach is not a pleasant experience.

Also, lactic acid build-up is quite toxic. The key is to find the ‘Goldilocks’ level of exercise that is just right for you.


There is more chance of getting sick when rundown or tired. Sleep helps us to heal. If you have trouble sleeping, you can support better sleep with a nutritional such as magnesium, calming herbs like chamomile or lemon balm teas, or herbal blends in tablets and powders. Gentle breath meditation is also most beneficial.


Zinc is a super immune booster. Generally, we need more zinc. In all my years of testing thousands of clients, I have only seen one person with good levels of zinc.

I don’t mean zinc just within the ‘normal reference range’ – I’m talking about the optimal level of zinc in ratio to the amount of copper you have in your body. If your copper level is high, then zinc needs to be higher.

These levels can be checked with blood or hair analysis. Without enough zinc, our immune system’s capacity is reduced. How much zinc depends on your circumstances, but many people do well on around 25-50mg of zinc per day; more if you are fighting an infection or have a compromised immune system.

Vitamin C

When talking about immunity, we cannot exclude vitamin C. There are different types of vitamin C you can take, depending on what best suits your body. My favourite is a mixed ascorbate form, while some do better with ascorbic acid and others find a liposomal form of vitamin C more suitable.

It’s best to consume a high amount of vitamin C that your body can tolerate, without running to the loo (high doses have a laxative affect). This is called ‘bowel tollerance’.

Fat soluble vitamins

Vitamins A, D and E are all great for the immune system. The sun provides us with Vitamin D which is an amazing immune supportive vitamin. Yet many clients I test have vitamin D levels less than optimal – even in summer, probably because many do the ‘slip, slop, slap’ to avoid skin cancer, or they may have defective genes to convert sun rays into vitamin D.

Did you know that your chances of getting melanoma, or recovering from melanoma, is worse if your levels of vitamin D are low? Interesting hey?

Vitamin A and E are antioxidants that not only support the immune system, but are also great vitamins to improve and support the health of the respiratory and gastrointestinal membranes.


Glutathione is one of the most important antioxidants the liver uses to detoxify our bodies. Why is this important for illnesses? As the immune system kills off organisms, the liver uses glutathione to clear the debris from our body. It’s the debris (toxins) that make us feel sick. Without an optimal supply of glutathione, the debris builds up to toxic levels which creates another layer of resistance to healing.

There are foods that naturally contain glutathione, such as avocado, asparagus, almonds, broccoli, cucumber, cabbage, tomatoes, spinach, garlic, chives, Brussels sprouts and walnuts – but our liver often needs more than we consume.

You can arrange tests to check levels of the antioxidants A, D, and glutathione.

Herbs and nutritionals

If you tend to get more than one cold a year, then you might consider some herbs to also support your immune system.

Some herbs and nutrients will increase Th1 and reduce Th2, and some can decrease Th1 and increase Th2. Other herbs and nutrients can help to balance or regulate the immune system via the gut no matter which way the immune system see-saw is swinging.

However, the best herb I know of that can balance the immune system is Astragalus Membranaceus. Numerous research articles show this herb improves the immune system. It is best used when the more acute symptoms of infection settle i.e. post infection, or to help support other immune functions.

Other herbs I like are: Andrographis which help to increase natural killer cells (a type of lymphocyte white cell); Cat’s claw – a herb not a kitty; Echinacea – not suitable for some auto-immune sufferers; and Olive leaf – love this stuff.

Another excellent balancer is the reiishi mushroom (and other types of super mushrooms) which can be found as an extract or in the dried form, but these only suit some people.

Bromelain (enzyme found in pineapple – especially high in the core) is also a good food to balance the immune system.

Lactobacillus species and certain bifidobacteria species from probiotic formulations are amongst the best gut (Th3) immune support but you do need the ‘right’ one for you. Taking any old probiotic isn’t necessarily going to do the job. Some species can make things worse.

If you already have a bacterial imbalance in the gut, then taking certain probiotics will feed the bad bugs instead of supporting your immune system. The bottom line here is to get guidance when choosing the right probiotic for your needs.

Of the nutrients, zinc, vitamin C, vitamin D and vitamin A as well as antioxidants all play a role in supporting a healthy immune system.

Because this is a complex issue, I suggest you speak to a qualified practitioner, who is experienced with dealing with immune system dysregulation, about the best choice of herbs, nutrients and probiotics to support T cell balance.

An analogy (a layman’s guide)

When I speak to my (non-scientific) husband about complex health conditions I often see a confused glazed look, so to explain in layman’s terms I like to use analogies. Here’s one I used about the immune system.

Imagine within your body is a powerful army, The army consists of billions of white blood cells. They occupy less than 1% of the blood’s volume, but they’re powerful and can pack a punch. After all, white blood cells are larger than the red cells.

The white blood cells, also known as leukocytes, are the body’s defence against disease. Some, the T-Cells, attack and destroy cells containing viruses and bacteria. Others, the B-Cells, produce antibodies against bacteria or fight malignant disease. (T for aTTack, B for antiBodies – get it!)

The army lurks in strategic locations throughout the body to cut off invaders such as allergies, viruses, germs, and other nasties. They stand by, ready for action, in different places in your body.

Forward scouts spot intruders and sound the alarm. Millions of army personnel (white blood cells) gear up instantly and attack in force and ‘all being well’ not only is the invader destroyed, but your body now has antibodies that will recognise and repel the virus next time before it has a chance to do any damage.

Note the phrase ‘all being well’. Like any army, when nourished with nutritious food and respected, it functions brilliantly.

But when disrespected with lousy food, alcohol, cigarettes, drugs, sugar or stress, your army’s efficiency plummets. Lethargy sets in, responses are sluggish from the brain, the soldiers stop working together effectively, thus leaving openings all around for invaders to attack.

Meanwhile, the army has to keep the soldiers fighting long past their retirement date; they cannot continue, so younger immature soldiers (white cells) are called out, but can’t repel the nasties. Eventually, through exhaustion, they get confused and start to attack the good cells in the body which we know as auto-immune disease.

But why is this so?

Because the brain thought, “She’ll be right, I’ll deal with that later. There’s no rush to be healthy and I’m sure not going to listen to what my body is trying to tell me.”

(Although not technically correct, my husband got it! He asked me to include it in this article for other non-scientific types…like him).

In conclusion…

Your immune system is extraordinarily complex…indeed miraculous. But it can’t do it all by itself. It needs your help, otherwise it can break down with potentially severe consequences.

The word ‘balance’ appears frequently in this article. To help strengthen your immune system, possibly the best advice I can give you is to ensure your life is ‘in balance’.  Eat sensibly, drink plenty of water, reduce stress or find ways to cope with it, exercise regularly (but not too much), ensure good gut health, look after your liver and the rest of your lymphatic system…and focus on all the good things in life.

And, it’s important to discuss your health options with an experienced knowledgeable health practitioner.

Your body is precious. Please don’t take it for granted.


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6 thoughts on “Our amazing immune system

Kerry Lyons 19 August 2020 - 6:40 am

Brilliant and informative article thankyou

sue 20 August 2020 - 5:18 pm

Thank you for taking the time to read the immune system article Kerry. Glad you enjoyed it. With love, Sue

Janine Pringle 18 August 2020 - 1:39 am

Thank you Sue for such a comprehensive guide to our immune system! I now realise I need to make some big changes to my eating/sleeping lifestyle!!!

sue 18 August 2020 - 8:31 am

So glad you like the article Janine, thanks for your feedback. Love sue

Joanne Foster 17 August 2020 - 1:57 pm

Love how you explained the way the bodies immune system work in tbe last part of your information.
I actually learnt alot of interesting information from this article which will help me in my Nutrition Course Ive just started.

sue 18 August 2020 - 8:32 am

Great to hear that you learnt a lot from the article Joanne. Thanks for your comment. Love Sue