5 Surprising Functions of your Immune System

Your immune system is your body’s shield against illness. It is armed with a network of organs, proteins and cells that work together to defend against harmful bacteria, viruses and toxins. Its job is to spot and attack foreign invaders (even those that are yet to be identified!), neutralising them before they can cause damage to the body.

Did you know that your immune system remembers every pathogen it encounters, building up an immunity over time? It's a sophisticated surveillance system housing trillions of specialised cells that extend far beyond your bloodstream, adapting and evolving with you.

We're still learning about the intricate language of the immune system and its influence on our wellbeing. Read on to get to know your innate defense mechanism on a deeper level! 


1. Your immune system can be strengthened like a muscle. 

Just as muscles grow stronger with regular exercise, your immune system can too! Regular movement may flush bacteria out from the lungs and airways, reducing your chance of catching a cold, flu or other illnesses. ​​Physical exercise causes changes in antibodies and white blood cells (WBC). WBCs are the body's immune system cells that fight disease. 

According to a recent study, moderate intensity exercise boosts the immune system by enhancing the circulation of immune cells in your body, making it quicker to identify and respond to pathogens1.

2. The majority of the immune system lies in the gut. 

 70-80% of your immune system resides in your gut2! The gut flora, or the microbiome, plays a crucial role in defending your body against foreign invaders by competing for space and nutrients that harmful microbes would otherwise use to thrive. This vast ecosystem of bacteria plays a crucial role in training your immune system to distinguish friend from foe.

It’s equally important to nourish from the inside out with a balanced diet rich in fibre, protein and wholefoods - this provides nutrients and also feeds the diverse species of bacteria in the gut. Fibre also helps to sweep toxins out of the gut and feeds the “good” bacteria. Amino acids found in protein also  help to maintain a strong gut lining, which allows for good absorption of nutrients and minerals. 

Research has shown that a healthy gut microbiome can significantly strengthen the body’s ability to mount a strong immune response, keeping you functioning at your best2

3. The immune system doesn’t have one centralised location in the body. 

Unlike organs such as the heart or liver, the immune system is distributed throughout the body. Instead, it's a decentralised network of cells and tissues within various organs playing critical roles. The thymus gland, located in the chest, is responsible for the development of T-cells, a vital component of the immune response. The spleen acts as a filter, removing pathogens and damaged blood cells from circulation. Lymph nodes, strategically located throughout the body, serve as communication hubs for immune cells and filters for pathogens and foreign invaders.  This decentralised structure allows for a rapid and coordinated response to threats, protecting the body from diseases no matter where they may arise.

4. Sunlight exposure boosts your immune system – and so do antioxidants! 

Sunlight exposure triggers the production of vitamin D, which plays a role in immune function. It helps to regulate the function of immune cells, protecting the body against pathogens. Research has even shown that vitamin D deficiency can be associated with an increased susceptibility to autoimmune diseases3.

Antioxidants, found in fruits, vegetables and whole grains, can also play a role in supporting the immune system. These compounds help combat free radicals, which can damage cells and contribute to inflammation. 

A study in the Journal of Investigative Medicine highlights that high levels of Vitamin D and antioxidants are linked to improved immune responses and a lower risk of infection3. While a balanced diet rich in antioxidants and moderate sun exposure can be beneficial, it's important to consult with your healthcare provider to determine the optimal vitamin D levels for your individual needs!

5. Your immune system is a complex balancing act. 

When functioning properly, your immune system mounts a targeted response to eliminate threats while minimising any damage to healthy tissues.  You don’t want this system to underreact and allow pathogens or infections to take hold! On the other hand, when the immune system overreacts, this condition is known as a cytokine storm4. A flood of inflammatory chemicals that can cause long-lasting damage to organs and tissues is released by the immune system itself. This is a serious complication that can occur in certain viral infections. 

True to the JSHealth philosophy of living a Healthy Life, the key to a healthy immune system lies in balance – with a diverse diet, regular movement and 7-8 hours of quality sleep to truly care for your immune system and allow it to function at its best.  


  1. da Silveira, M.P., da Silva Fagundes, K.K., Bizuti, M.R., Starck, É., Rossi, R.C. and de Resende e Silva, D.T. (2020). Physical exercise as a tool to help the immune system against COVID-19: an integrative review of the current literature. Clinical and Experimental Medicine, [online] 21(1). doi:https://doi.org/10.1007/s10238-020-00650-3
  2. Wiertsema, S.P., van Bergenhenegouwen, J., Garssen, J. and Knippels, L.M.J. (2021). The Interplay between the Gut Microbiome and the Immune System in the Context of Infectious Diseases throughout Life and the Role of Nutrition in Optimizing Treatment Strategies. Nutrients, [online] 13(3), p.886. doi:https://doi.org/10.3390/nu13030886
  3. Aranow, C. (2011). Vitamin D and the immune system. Journal of investigative medicine : the official publication of the American Federation for Clinical Research, [online] 59(6), pp.881–6. doi:https://doi.org/10.2310/JIM.0b013e31821b8755
  4. Mohammed, M.S. (2023). Fighting cytokine storm and immunomodulatory deficiency: By using natural products therapy up to now. Frontiers in Pharmacology, 14. doi:https://doi.org/10.3389/fphar.2023.1111329