How does the immune system work?
The immune system is far more complex that the average individual would understand as most of us think of our immune system simply to fight infections such as cold or flu, however it is actually a network consisting of organs, cells and proteins which not only fights infection but also protects our own body’s cells.
The immune system is able to store a memory bank of all germs (microbes) that is has ever encountered so that if it is faced with these again, it can quickly attack and destroy it so that we don’t get sick.
When our immune system is not functioning optimally, we can get abnormalities which can lead to allergic reactions, immunodeficiency or even autoimmune disorders. Overactivity of the immune system can cause allergic diseases such as food allergies, insect allergies, pet allergies, hay fever, asthma, hives, dermatitis and eczema. It can also cause autoimmune diseases such as multiple sclerosis, specific types of thyroid disease, type 1 diabetes, lupus, systemic vasculitis and rheumatoid arthritis.
Underactivity of the immune system is also known as immunodeficiency and it can make people vulnerable to infections which can even be life threatening. Immunodeficiency can either be inherited such as in immunodeficiency diseases, arise as a result of medical treatments such as due to corticosteroids or chemotherapy or it can be caused by another disease such as HIV/AIDS or certain types of cancer.
The key components of the immune systems include;
- white blood cells
- antibodies
- complement system
- lymphatic system
- spleen
- bone marrow
- thymus
The body also has another line of defence against pathogens which includes organs of our body such as our skin which acts as a waterproof barrier secreting oil to kill bacteria, our lungs which produce mucous to trap foreign particles plus small hairs to push the mucous so it can be coughed out, our digestive tract which also has a mucous lining and acid in our stomach to kill microbes and lastly other defences such as tears, body oils, urine and saliva which contain anti-bacterial enzymes to reduce infection risk.
Innate vs Adaptive Immunity
The immune system is made up of the innate (general) immune system and the adaptive (specialized) immune system which work closely together and take on different tasks. The innate immune system is the body's first line of defense and it responds in the same way to all germs and foreign substances, which is why it is sometimes referred to as the "non-specific" immune system. It acts within a few hours if germs are detected through a wound on the skin however its not always effective from stopping the spread of germs so that’s when the adaptive (specialized) immune system takes over.
The adaptive immune system specifically targets the type of germ that is causing the infection and if it has seen it before, it remembers it, but if not, it can be much slower to respond than the innate immune system. This is why there are some illnesses you can only get once in your life, because afterwards your body becomes “immune” to them as it reacts immediately and you might not even get symptoms or they will at least be milder.
The adaptive immune system is made up of:
- T cells in the tissue between the body's cells
- B cells (also in the tissue between the body's cells)
- Antibodies in the blood and other bodily fluids
When it comes to adaptive immunity, vaccines are often administered during childhood, when travelling or when people are considered ‘high risk’ for infection and illness. Vaccines then make our bodies produce antibodies to copy the bodies natural immune response . Vaccines will react differently in people due to individual variation in health status, age, lifestyle and occupations too as some people may be exposed to pathogens more often than others such as a nurse or school teacher.
What is the difference between acute and chronic inflammation?
When our immune system is compromised we can either have an episode of acute inflammation or chronic inflammation. Acute inflammation is the most well-known type of inflammation as it is when the body temporarily responds to injuries, such as a cut, or infection, such as invasion by germs such as bacteria, virus or fungi by sending inflammatory cells to the site affected and it starts the healing process. With infection, we often develop a fever too which can kill some microbes due to the increase in temperature which also triggers the body’s repair process.
Chronic inflammation on the other hand can take a few days to even weeks for its onset, then it can last for months or even years. It can have periods where it is worse or improving however it is constantly sending inflammatory cells even when there is no immediate dangers to the body such as in rheumatoid arthritis where it attacks itself causing damage to our own body cells. Chronic inflammation is also linked to conditions such as obesity, cardiovascular disease and type 2 diabetes.
What foods can support our immune system?
A diet which is rich in plant-based foods is important for immune health as it contains a wide range nutrients including;
- Vitamin C - helps to increase white blood cell production which helps to fight infection – key food sources include citrus fruits, berries, melons, tomatoes, capsicum and broccoli
- Beta Carotene - converts into Vitamin A which is an important anti-inflammatory vitamin that helps antibodies respond to toxins such as a virus. Food sources of beta carotene include sweet potato, spinach, carrots, broccoli and mango.
- Vitamin D – a fat soluble vitamin and its essential for immune function as it helps regulate the body’s immune response. It is found in fatty fish and eggs plus sunshine exposure for around 15-20mins a few times per week will help the body produce this too.
- Vitamin E - is also a fat soluble vitamin and it is also essential in supporting immune function plus it cannot be stored in the body and must be consumed regularly. It can be found in nuts, seeds and dark leafy greens.
- Zinc – required for the cells of the immune system to function and is found in wheat germ, beans, seafood, shellfish, poultry, nuts and tofu.
- Fermented foods – contain probiotics which are good bacteria to stimulate the immune system to fight off disease. These foods include yoghurt kimchi, kefir, kombucha, aged cheese, tempeh and sauerkraut.
- Pre-biotics – are essential fuel for the gut-microbiome which is important for gut health and overall immunity. They are found in high amounts in foods such as asparagus, onion, chickpeas, lentils, leeks, whole-grains and garlic.
- Protein - essential for producing germ-fighting compounds within the immune system. Protein is found in all animal foods such as meat, dairy, fish, poultry and eggs plus it it also found in plant foods such as legumes, lentils, nuts and seeds.
- Anti-oxidants – can enhance immune function and are anti-inflammatory. They are found in high amounts in garlic, ginger, green tea, spices such as turmeric as well as in many plant based foods.
- Vitamin B6 – is important for the lymphatic system and red blood cell production. It is found in chicken, turkey, salmon, tuna, hommus and banana.
- Hydration – water is essential for immunity as it helps produce lymph which carries white blood cells and other immune cells throughout the body to clear infection.
What is the connection between gut health and immunity?
Gut health and immunity are closely linked as 70% of the immune cells reside within the gut. The intricate involvement of the gut and immune system involves thousands of different species of bacteria and other microorganisms that are residents in the gut however the immune system needs to differentiate these bacteria from invading pathogens whilst also maintaining self tolerance to avoid autoimmunity. A healthy gut microbiome can assist with providing a host of health benefits by regulating immune homeostasis.
However immune dysregulation may occur when the gut bugs are out of balance leading to autoimmune disorders . A faulty immune system is responsible for the most common types of inflammatory arthritis including gout, rheumatoid arthritis and juvenile idiopathic arthritis just to name a few…
The gut microbiome can be disrupted by taking antibiotics, smoking, stress and a poor diet. This can be the trigger for abnormal immune response leading to inflammation in the gut. This inflammation can then cause problems in other areas of the body as inflammatory cells escape in the bloodstream and move throughout the body.
Why is there a rise in autoimmune conditions and what is the role of the immune system here?
Autoimmune conditions are reaching epidemic levels with some studies estimating an increase of 3-12% annually. The most common marker of autoimmunity is antinuclear antibodies (ANA) and the prevalence of these nearly doubled between 1988-2012 according to various studies. Autoimmune disease is a group of illnesses, compromising of more than 100 disorders, in which the immune system mistakenly attacks the body’s own tissues. Some of these common conditions include psoriasis, coeliac disease, multiple sclerosis, type 1 diabetes and rheumatoid arthritis as well as many rarer conditions.
It is not fully understood why the prevalence of autoimmune diseases are increasing as its not due to genetics alone. It is thought that perhaps it is due to environmental factors such as medications, pollutants, toxins and viral infections along side lifestyle factors such as diet, lack of sleep, increased stress and reduced physical activity also plays a role.
Therefore in summary, to improve your immunity you should eat a well-balanced diet with pleny of wholefoods, protein and heathy fats as well as avoid alcohol, smoking and processed foods whilst also exercising regularly, getting into a good sleeping habits and managing stress levels.
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