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Antioxidants and your immune system – can they really help?

The interplay between the immune system, oxidative stress and nutrients that target both of these pathways is a popular topic, especially during the winter months. Modern life exposes us to increased toxins, pollution, nutritional deficiencies, stress, poor liver and digestive function and inflammation which all put additional stress on the immune system, often leaving it vulnerable to attack.

Antioxidants, including vitamins C and E, and phytochemicals including carotenoids and polyphenols have always been of interest in health for their role in the prevention of oxidative stress, inflammation and degenerative diseases. In this week’s article we are going to look closely into a range of antioxidants and how they play a key role in supporting the function of the immune system.

What is the immune system? 1

The immune system is a complex network of proteins, cells, tissues and organs that help defend the body against pathogens by identifying and mounting a response to invaders. The immune system consists of white blood cells, bone marrow, the lymphatic system, the tonsils, appendix, adenoids, spleen and thymus.

The immune system consists of two subsystems, the innate (non-specific) which provides general immune defence including natural killer cells and phagocytes acting as your first line of defence, and the adaptive (specific and acquired) immune system, involving lymphocytes which help fight infection by producing antibodies. Lymphocytes are white blood cells and include T and B cells which are manufactured in the bone marrow. T cells are responsible for the continuous monitoring of cells for signs of infection, destroying infected cells when needed, while B cells produce antibodies that bind to an antigen, flagging it as an invader to be destroyed by other immune cells.

Among other factors, low grade chronic inflammation is a major contributor to a dysregulated immune system and increased risk of poor health. The immune system is closely linked to other aspects of physiological regulation such as circadian rhythms, hormonal and metabolic regulation and, what we are most concerned about in this article, the utilisation of nutrients.

Skip to Key Takeaways

What are free radicals and antioxidants 2

Reactive oxygen species (ROS), free radicals which contain oxygen, are generated both exogenously in response to environmental pollutants, toxins, high blood sugar levels, poor nutrition and UV exposure, and endogenously, as a normal byproduct of cell processes, including the generation of energy in the mitochondria.

Free radicals are reactive chemicals that have an unpaired electron, they aim to stabilise themselves by stealing an electron from other molecules, leaving the latter damaged and unstable. While free radicals are constantly being formed and are often necessary for important body processes such as helping the immune cells to fight infection, an excess can cause harm, especially if they are not balanced by antioxidants. This process leads to oxidative stress and cell damage or death, which in turn damages DNA, promoting the development of many degenerative diseases such as cardiovascular disease.

An antioxidant is a compound that counterbalances ROS and stabilises free radicals by donating one of their electrons to neutralise this reaction, without being damaged itself, helping to maintain homeostasis. An adequate supply of antioxidants are needed to disarm free radicals. While the body produces its own antioxidants such as glutathione, COQ10 and alpha lipoic acid, a range of factors such as diet and environment may increase an individuals need for further support.

The antioxidant defence must minimise levels of ROS whilst still allowing ROS to perform roles of cell signalling and redox regulation. It is worth noting that oxidative and antioxidative stress are both damaging and so determining a person’s level of support is essential.

If free radical production exceeds antioxidant status, ROS can cause oxidative damage to vital components of the cell, including proteins, lipids and DNA. The free radicals lead to pro-inflammatory transcription factors and an increase in inflammatory cytokines, making the control of inflammation and oxidative stress key factors in the preventing the development of degenerative diseases.

Which antioxidants can support the immune system?

Vitamin A 1, 3

Vitamin A is a fat-soluble vitamin that is found in the form of beta-carotene within plants such as carrots and sweet potatoes, and in high concentrations in animal based foods such as liver. Vitamin A is an anti-inflammatory nutrient that promotes and regulates both the innate and adaptive immune system and is involved in:

  • The maintenance of a healthy mucus layers and the integrity of epithelial linings in the intestines, lungs and urinary tract, a vital structural defence against pathogens.
  • Retinoic acid (active vitamin A) mounts a response to pathogens and is involved in activating NK cells, T- cells and phagocytosis.
  • Retinoic acids help to regulate differentiation, maturation and functions of the innate immune system
  • Vitamin A deficiency is important for the function of neutrophils and macrophages and natural killer cells
  • Vitamin A plays a role in the development of both T and B cells

Vitamin C 1, 4

Vitamin C supports a variety of cellular functions in both the innate and adaptive immune system and can be found in citrus fruits and a variety of vegetables. As a common supplement, it is often taken to protect against and shorten the duration of colds and flu, and for good reason, research suggests that vitamin C supplementation can reduce infection duration and improve respiratory conditions as well as:

  • Directly quench free radicals, reducing the cascade of oxidative stress
  • Stimulates migration of neutrophils to infection site as well as supporting their apoptosis
  •  Supports lymphocyte production and function
  • Increases interferon production – proteins that are made and released in response to pathogens like viruses
  • Enhances natural killer cell activity
  • Involved in the differentiation and proliferation of T and B cells
  • Stimulates phagocytosis and aids in macrophage removal
  • Supports the epithelial barriers of the body against pathogens

Vitamin E 5

Vitamin E is a fat-soluble antioxidant that is found in nuts, seeds and grains. It is involved in:

  • The maturation and functions of dendritic cells and antigen presenting cells that act as messengers between the innate and adaptive immune system. Dendritic cells are present on the skin and important lining such as the digestive tract and mouth
  • Increases natural killer cell activity
  • Improve T-cell proliferation
  • Modulates Th1 and Th2 responses
  • Improves immune synapse formation in naïve T cells and the initiation T cell activation signal

Zinc 1

Zinc is a cofactor for over 200 enzymes involved in the bodies antioxidant defence system. Deficiency has been linked to low T cell and B cell function and other reduced immune markers, giving zinc a reputation as an antiviral mineral. It is involved in:

  • Cell growth and differentiation of immune cells
  • Maintains macrophage and neutrophil function while supporting NK cell activity
  • Modulating cytokine release
  • Developing and activating T-lymphocytes

Selenium 1,6

Selenium is an essential antioxidant and supports the production of the master intracellular antioxidant, glutathione. It is needed for selenoprotein synthesis, most notably glutathione peroxidase, which functions to protect the body from oxidative stress. A deficiency of selenium and consequently selenoprotein expression can increase inflammatory cytokines and reduce the functioning of the immune system.

Polyphenols 7

Polyphenols are phytochemicals that have antioxidant, anti-inflammatory and immunomodulatory properties and can be categorized into:

  • Flavonoids – Include quercetin, catechins, anthocyanins and are found in broccoli, kiwi, blueberries, onions, tea and red wine.
  • Polyphenolic amides – capsaicinoids and avenanthramides
  • Phenolic acids – chlorogenic acids and ferulic acids found in red fruits and onions
  • Stilbenes – found in resveratrol
  • Ligans – found in linseeds and other grains and cereals.
  • Other – ellagic acid and curcumin

The benefits of polyphenols from plants are far reaching, having a positive impact on brain health, digestive function and immunity. They have been found to reduce insulin resistance, support blood sugar levels and support bone health, reducing osteoporosis risk. The majority of polyphenols travel to the large intestine where they have a prebiotic effect, reducing inflammation and helping to support the integrity of the mucosal and epithelial lining, therefore enhancing mucosal immunity, which as we know plays a vital role in immune regulation.

Polyphenols can be found in a wide range of plant foods, and variety is key, incorporating a range of colourful fruits and vegetables into every meal alongside a source of healthy fat (olive oil, nuts, avocado) can increase absorption of these beneficial compounds.

Quercetin 8,9

Quercetin is a flavonoid found in fruits and vegetables such as apples, brassica vegetables, onions, tomatoes and tea which have antioxidant, antiviral, anti-inflammatory, anti-diabetic and anti-carcinogenic properties. It has been studied notably for its role in stimulating mitochondrial biogenesis, as a mast cell stabiliser and for its use in supporting the integrity of the tight junctions in the gut.

Curcumin 10

Curcumin is a potent polyphenolic compound found in turmeric and has been found to have neuro and cardiovascular protective effects. Alongside its potent anti-inflammatory effects curcumin is an effective ROS scavenger, supports phase two liver detoxification and can increase levels of glutathione.

COQ10 11, 12, 13

COQ10 not only possesses antioxidant and anti-inflammatory properties, it is highly concentrated in the mitochondria where it is directly involved in energy production, which is important as the immune system is very energy intensive. Research has also found that COQ10 can help to reduce oxidative stress generated from high intensity exercise.

COQ10 plays a role in cell signalling pathways and enhances immune cell activity, several studies have linked lower levels of COQ10 with increased infection risk, while adequate COQ10 levels were found to increase levels of T-lymphocytes and IgG antibodies and inhibit the SARS-CoV-2 virus.

Alpha-Lipoic acid 14, 15, 16

Alpha-lipoic acid (ALA) can regenerate other antioxidants such as Vitamins E, C and glutathione and increase catalase and superoxide dismutase, potent first line defence antioxidant enzymes. ALA can cross the blood brain barrier, helping to reduce neuroinflammation and downregulate pro-inflammatory cytokines. It has been studied for its immunomodulatory effects, including its ability to stop the entry of SARS-COV-2 into the cell. ALA can be found in small amounts in foods such as broccoli, tomatoes, spinach, red meat and Brussel sprouts.

Glutathione 17

Glutathione is the bodies master antioxidant, it is vital for immune system functioning and acts as a intracellular redox buffer to protect cells against the damaging effects of oxidative stress. Glutathione is synthesized from cysteine, glycine and glutamic acid and plays a role in modulating the immune system in many ways, for example through its effects on lymphocyte function and NK cell activity. It is a cofactor for several antioxidant enzymes, can regenerate vitamins C and E, supports mitochondrial function and maintains mitochondrial DNA.

N-Acetyl Cysteine (NAC) 18

An important biological function of NAC is its ability as a precursor to boost levels of glutathione, which as described above is the most powerful antioxidant in the body. NAC itself has antiviral and antioxidant properties to protect against cellular damage and can reduce the formation of inflammatory cytokines, while helping to restore NK cells.

Resveratrol 19

Resveratrol belongs to the stilbenes polyphenol category and is found in grapes, red wine, mulberries and rhubarb. It holds potent antioxidant, anti-inflammatory and immune regulating benefits due to its ability to act on the enzymes involved in the production of eicosanoids, targeting inflammatory cytokines and inhibiting NF-kB. Resveratrol is popular due to its use in mitochondrial biogenesis and as an activator of sirtuin, a protein which can influence aspects of metabolic health and ageing.

Green Tea 20

Green tea polyphenols including its active compounds epigallocatechin-3-gallate (EGCG) and epicatechin-3-gallate (ECG) act as antioxidants to attenuate oxidative stress. Research supports its immunomodulating effects on T cell functions including T cell activation, proliferation and differentiation.

Lutein and Zeaxanthin 21

Lutein and Zeaxanthin are carotenoids most commonly known for their antioxidant value with additional eye health benefits, providing protection against eye related degenerative disorders. Lutein, zeaxanthin and meso-zeaxanthin are highly concentrated in the retina of the eye and the protective effects of these compounds include targeting ROS and absorbing damaging light. 

Lycopene 22, 23, 24

Lycopene is an antioxidant and belongs to the carotenoid family, it can support immune function by enhancing the proliferation of lymphocytes, influencing NF-kB, supporting T cell function and reducing the production of inflammatory cytokines. Intake of carotenoids, including lycopene have been found to lower the risk of certain cancers. This anti-inflammatory compound can even help protect against sunburn and is rich in cooked tomatoes, watermelon and grapefruit.

Grapeseed 25, 26

Grapeseed extract (GSE) is naturally rich in flavonoids, phenolic acids, anthocyanins and oligomeric proanthocyanidins complexes (OPCs) and can improve the action of other antioxidants in the body. Studies have found GSE can specifically help reduce the oxidation of fats in the blood, which together with its anti-inflammatory effects can help support cardiovascular health. GSE can also benefit the gut microbiome by supporting the beneficial microflora and reducing lipopolysaccharides (LPS), which are bacterial toxins that promote inflammation, further supporting the immune system.


There are many beneficial compounds including vitamins, minerals and polyphenols that have potent antioxidant, ROS quenching actions in the body and help to modulate inflammation. While oxidative stress is unavoidable, the use of antioxidant foods and supplements can help assist the functioning of the immune system to support optimal health.

Key takeaways

  • Modern life exposures us to increased toxins, pollution, nutritional deficiencies, stress, poor liver and digestive function and inflammation which all put additional stress on the immune system, often leaving it vulnerable to attack.
  • The immune system also consists of two subsystems, the innate (non-specific) which provides general immune defence using natural killer cells and phagocytes and is part of your first line of defence, and the adaptive (specific and acquired) immune system, involving lymphocytes, which target specific germs that the body has already come into contact with.
  • Free radicals are reactive chemicals that have an unpaired electron, they aim to stabilise themselves by stealing an electron from other molecules, leaving the latter damaged and unstable.
  • An antioxidant is a compound that works by counterbalancing reactive oxygen species (ROS) and stabilising free radicals by donating one of their electrons to neutralise this reaction, helping to maintain homeostasis
  • If free radical production exceeds antioxidant status, ROS can cause oxidative damage to vital components of the cell, including proteins, lipids and DNA
  • Vitamins A, C, E, and minerals zinc and selenium have potent antioxidant actions that support the immune system
  • The benefits of polyphenols from plants are far reaching having a positive impact on brain health, digestive function and immunity.
  • Many compounds found in food and supplements possess potent antioxidant capabilities. These include quercetin, curcumin, COQ10, Alpha lipoic acid, glutathione, NAC, resveratrol, green tea, lutein, zeaxanthin, lycopene and grapeseed.
  • While oxidative stress is unavoidable, the use of antioxidant foods and supplements can help support the functioning of the immune system to support optimal health.

Recommended Cytoplan products 

Cell-Active Glutathione

Glutathione is the most abundant antioxidant in the body and is often referred to as the ‘master antioxidant’ because of its ability to recycle other antioxidants, as well as protect cells from oxidative damage and free radicals, which contribute to ageing and disease. Cell-Active Glutathione cobmines liposomal glutathione with alpha lipoic acid, ginkgo biloba, rosemary, resveratrol and n-acetyl-l-carnitine.

Antioxidant plus COQ10

This supplement contains Co-enzyme Q10 (CoQ10) alongside excellent levels of vitamin C, vitamin E and selenium which all contribute to the protection of cells from oxidative stress; this means they are antioxidants. Antioxidant plus CoQ10 can be taken alongside an all-round multivitamin and mineral formula.

Cell-Active Curcumin

Our highly bioavailable and high-strength Cell-Active Curcumin Plus is a natural phytonutrient complex containing liposomal curcumin and gingerols from ginger root


Eye Cyt is a high potency antioxidant formula, containing a comprehensive range of nutrients relevant for eye health. The formula contains a powerful mix of carotenoids and flavonoids comprising natural vitamin E, lutein (providing Zeaxanthin), bilberry extract and grape seed extract (providing polyphenols).


Phytoshield is a very potent and powerful phyto-antioxidant nutrient formula, containing high levels of flavonoids and carotenoids, as well as green tea extract (95% polyphenols)


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All of our blogs are written by our team of expert Nutritional Therapists. If you have questions regarding the topics that have been raised, or any other health matters, please do contact them using the details below:
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Last updated on 10th April 2024 by cytoffice


4 thoughts on “Antioxidants and your immune system – can they really help?

    1. Hello Colin,
      Thank you for your kind feedback, we’re really glad to hear you found the article so useful.

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