Can you boost your immune system? It is very common to see companies and wellbeing influencers promoting products that claim to boost your immune system. But would you really want to do that? In this article, I will explain how your immune system works and why boosting your immune system is a misnomer. I will also explain how ‘anti-oxidants’ work and why antioxidants aren’t as effective as they are made out to be. 

Age of ‘boosting’

During the pandemic, ‘booster shots’ were given for the COVID vaccine. However, when it comes to your natural health, it is very common to hear of foods or products being described as ‘immune-boosting’.

Indeed, it is estimated that up to 2% of products globally are promoted as being linked to immunity. You see this all the time. From specific fruits and vegetables such as citrus fruits and cruciferous vegetables, to ‘on the go’ breakfast smoothies and fermented drink products such as kombucha. But is it possible for specific foods to affect your immune system? To answer this question, you need to understand how your immune system works.

What is the immune system 

Your immune system (including the lymphatic system) is the principle basis by which the body protects itself from micro-organisms. On a daily basis, the body is exposed to a whole host of bacteria, viruses, fungi, parasites as well as other irritants. The immune system’s primary role is to systematically neutralise such pathogens and facilitate their removal from the body. It also removes the body’s own cells which have been active in an immune response against itself (ie ‘auto-immunity’). 

The immune system is further made up of your ‘innate immunity’ and ‘adaptive immunity’. The innate immune system is the one that is highly responsive and constantly patrols the body looking for invaders. One of the key responses of the innate immune system is acute inflammation. Inflammation is the body’s first response to a situation. Typically, this would be from some form of insult to the body causing injury or irritation. For example from physical wounds, foreign objects, pathogens, chemical toxins, heat or radiation. Its telltale signs are redness, swelling, heat and pain. 

boost your immune system

The adaptive part of the immune system works in a more generic way. It produces antibodies which then attach to pathogens in order to neutralise them. On average, it takes around 5- 10 days for the immune system to produce enough antibodies to deal with an infection. During this time, the innate system continues to work to propel the invader and keep it from multiplying. 

‘Boosting’ your immune system

Whilst the idea of ‘boosting’ your immune system may seem intuitive, the body doesn’t work like that. The body is constantly producing immune cells, far more than is required. These cells remove themselves from the body through a process known as ‘apoptosis’. Furthermore, because the immune system is so complex, it is impossible to identify how many immune cells are required and in what mix for it to function at an optimal level. 

What’s more, even if you did manage to increase the sensitivity of the innate immune system, then you would be frequently unwell. You would be suffering from a runny nose, fever and overall feeling quite lethargic, as your immune system becomes hyper-aroused to the presence of any invader or foreign object. The immune system does a remarkably good job at keeping you healthy, considering how regularly you are exposed to foreign invaders.

When you become ill, the symptoms you experience are your body’s response to the infection. A sore throat, for example, is a result of inflammation and fever is the body’s response to increasing the temperature of the body to help kill the invader. In this context, rest is the best medicine.

Overall, when it comes to the immune system, it needs to find the right balance between being responsive to pathogens and exercising sufficient restraint. When the immune system becomes highly reactive and inflammation becomes chronic, then auto-immune conditions can occur like rheumatoid arthritis, type 1 diabetes, and multiple sclerosis amongst others. Or, the immune system mistakenly reacts to harmless foreign objects such as peanuts or pollen, giving rise to allergies (some of them life-threatening). 

Maintaining a balanced & healthy immune system 

The gut is the largest immune organ in the body. Every time you eat or drink something, the digestive tract has to filter all the plant and animal proteins as well as other microbes and determine whether they are fit for consumption or harmful to the body. In the latter case, the drastic effects of food poisoning are testimony to the body’s attempt to rid itself of any harmful invader. 

So, when it comes to maintaining an optimal immune system, having a healthy and balanced diet is the first start. This means eating a diet that includes the right mix of vitamins and minerals necessary for healthy digestion. When it comes to the marketing of products that promote immune-enhancing qualities, they will claim that they ‘contribute to the normal function of the immune system’. In other words, what a balanced, nutritious diet would otherwise provide. 

Eating a diet that is also high in fibre goes a long to supporting a healthy digestive tract, including the microbiome that resides in the gut. The microbiome feeds off the fibre in the digestive tract to produce short-chain fatty acids (SCFAs). SCFAs assist with metabolism, contribute towards maintaining homeostasis, have anti-inflammatory properties, as well as helping to regulate blood pressure.  


Health benefits of ‘enhanced immunity’ products 

If you already have a balanced diet, will consuming extra doses affect the immune system? When it comes to specific foods, it is difficult to assert with confidence the connection between food and immunity. Many tests that are shown to have promise in the lab do not hold up in large-scale human trials. This is because of the complexity of the immune system and its many layers of cells, physical barriers and chemical signals. 

Vitamin C is often mentioned as having qualities that can help the immune system fight off viruses. Studies consistently suggest that taking Vitamin C has no effect upon the incidence of common colds. It may reduce the duration and severity of the common cold (although getting such vitamin C through dietary means is sufficient (> 0.2g)). That said, Vitamin C may have anti-cancer effects when given in high does intravenously. 

How antioxidants work

The same applies to antioxidants. Antioxidants are those molecules that are capable of neutralising the harmful effects of free radicals that are produced and circulate throughout the body. They include Vitamin C and E, and plant-based polyphenols. Free radicals are molecules in the body that have an odd number of electrons (ie an ‘unpaired’ electron). Free radicals like to be in pairs so they become ‘restless’ and hence are unstable. They interact with proteins, fats and carbohydrates to degrade them.  

Antioxidants work by giving up some of its electrons so that the free radicals become stable. A chain reaction then results whereby new free radicals are created and the cycle continues until those newly created free radicals are deactivated. 


Although it is well-recognised in lab studies that dietary antioxidants have powerful free-radical neutralising effects, when it comes to real-world studies, the results have been disappointing. This is because each dietary antioxidant can only neutralise one free radical. On the other hand, with a healthy diet, the body produces antioxidant enzymes (such as glutathione) that are capable of neutralising thousands of free radicals. 

This is one reason why the spice turmeric (and its active component) curcumin, has had inconsistent clinical effects in human trials. Furthermore, taking turmeric supplements may even cause injury to the liver. 


During the winter months, it is very common to hear of foods and product that ‘boost’ your immune system. Yet, the complexity of the immune system means that is impossible to state with certainty how foods are going to have a specific impact upon the immune system. Nor is it necessarily desirable. The best thing you can do is to eat a balanced and healthy diet that is rich in fruits, vegetables, legumes and complex carbohydrates. Along with other integrative functional lifestyle measures such as regular exercise, focusing on maintaining a healthy diet is the best thing you can do to support your immune system.

If I can help you with your wellbeing, please feel free to get in touch or email me at


Dr Carole Hungerford, The Good Body Guide, 2009, Marion Boyars Publishers Ltd, UK.

Steve Parker, The Concise Human Body, 2019, Penguin Random House, UK.

Kamal Nahas, ‘The truth about the foods said to boost your immune system’, New Scientist, 2 November, 2022

Praveen Krishnamurthy and Ashish Wadhwani, ‘Antioxidant enzymes and Human Health’, November 2012.

J Sathiva Jeeva, J Sunitha, R. Anathalakshmi, S, Raikumari, Maya Ramesh, Ramesh Krishnan, ‘Enzy.matic antioxidants and its role in oral diseases, Journal of Pharmcy & Bioallied Sciences, 2015 August 7(Suppl 2): S331-S333.

Harvard Medical Review, ‘How to Boost Your Immune System’, February 15 2021

Henry Jay Forman & Honggiao Zhang, ‘Targeting oxidative stress in disease: promise and limitations of antioxidant therapy’, Nat Rev Drug Disov, 20, 689-709 (2021)