The Immune System


The immune system is complex, intricate and interesting and as new information about this system is discovered and new drugs and natural remedies are developed it makes sense to keep informed. In this article, we will take a look at how your immune system works so that you can understand what it is doing for you each day.

Having a healthy immune system is vital to ensure quality of life. Our immune systems have the amazing capacity to protect us from disease and fight off foreign invaders that may cause our body harm. The immune system is often not given much thought until it stops operating efficiently.

If the immune system does not receive adequate nutrition it can become weakened reducing the ability to fight off infection or illness, it can leave you feeling run-down and fatigued, and increase the allergenic response.


How does it work?

Humans are surrounded by a plethora of viruses and bacteria every day. To them, we are a smorgasbord, offering resources they can use for energy and reproduction. Fortunately for us, penetrating the human body is no easy task.

Skin is thick and hard to penetrate and produces substances that are harmful to invaders. Openings such as the nose, eyes and mouth are protected by fluids or mucus that traps harmful invaders.

The respiratory tract has mechanical defenses in the form of cilia (tiny hairs that remove particles). Intruders that penetrate as far as the stomach face a sea of gastric acid to destroy them.

When bacteria or virus penetrate these defenses, this is where our immune cells kick in. Immune cells work with proteins to obliterate foreign intruders that enter the body. There are various immune cells, each with its own functions; some release special proteins called antibodies that mark intruders for destruction by other cells. Others seek out and devour invading organisms (phagocytosis), and others destroy infected or mutated body cells.

Immune cells called ‘memory B cells’ are produced when we are exposed to a pathogen and become reactivated if we are re-exposed, it will strike quickly. As a result, an invader that tries to attack the body a second time will most likely be wiped out before there are any symptoms of disease.

The immune system works hard to keep us in good health, so it makes sense to support it as much as possible.


The role of diet

All immune cells are made from nutrients derived from the foods we eat. Different cells require different nutrients, for example lymphocytes require B12, folate, alanine, glutamine, glutathione, DMG, lycopene, vitamin A and C. So as you can see, diet can affect the immune system by hindering or abetting the production of immune cells.


The role of Antioxidants

Antioxidants are needed to quench free radicals as they can damage immune cells and wipe out cytokine pathways[i]. Antioxidants are crucial to mop up after an immune response as the activated neutrophils produce free radicals and activation of phagocytes inevitably results in the superoxide anion radical. Macrophage (an immune system cell) releases the free radical nitric oxide to destroy pathogens. If it’s over produced, or the antioxidant balance is low, the nitric oxide will turn and damage the macrophage itself thereby impairing its ability to fight off invaders.


Dietary inclusions

To keep the immune systems strong and healthy, not only do you need to look after yourself (i.e. adequate sleep) but consume a healthy diet. Including fruits, vegetables, whole grains and good protein sources, this will ensure adequate nutrients for the immune system.


Some helpful nutrients for the immune system:



Foods: pomegranate, goji berries, sweet potatoes, carrots, kale, spinach, collard greens.


Beta carotene is the most popular member of the carotenoid family. They can be converted to vitamin A in the body when needed, ensuring that an optimum level of Vitamin A is maintained. Beta-carotene is important for immune function, as it can increase and activate our white blood cells and also improve immune cell communication[ii]. Beta-carotene is also essential for wound healing.


Vitamin A

Foods: chili, sweet potato, carrots, dark green leafy vegetables, dried apricots


Vitamin A may help repair the epithelial cells, enhance antibody response and lymphocyte proliferation in response to antigens.Vitamin A has an immunostimulant affect by increasing the function of immune and mucosal cells, by working at the genetic level to promote the process of cell differentiation (epithelial cells and goblet cells). Is an essential nutrient for the production of the gastrointestinal tracts protective antibodies (IgA)[iii],[iv].



Foods: pumpkin seeds, oysters, beef, sesame seeds, lamb, dark chocolate


Zinc may promote the proliferation of lymphocytes, switch the immune system to more cellular dominance immunity, inhibit histamine release by binding to the receptor site and thymulin,requires zinc in an equimolar ratio for biological activity[v]. Thymulin regulates the differentiation of the immature thymocyte subpopulation, the function of mature T and natural killer cells and also functions as a transmitter between the neuroendocrine and immune systems.

Zinc’s importance in regulating gene expression is crucial to gastrointestinal epithelia and immune cells.

Zinc is required for over 100 enzymes, may reduce oxidative stress[vi]. Involved in maintenance, repair and morphogenesis of the skin, also moderate zinc deficiency may manifest as rough skin and delayed wound healing.


Vitamin C

Foods: pomegranate, goji berries, parsley, broccoli, capsicum, strawberries, oranges, papaya, cauliflower, kale, mustard greens


Vitamin C has the ability to assist antibody production, white blood cell formation, interferon production and phagocytosisiii,[vii]. Vitamin C may reverse oxidation of antioxidants and free radicals caused by immune responsesiv,iii.


Vitamin E

Foods: sunflower seeds, almonds, dried herbs, chili powder, avocado


Involved in modulation of the immune system, including differentiation of naïve T cells in the thymus. Vitamin E is also a key antioxidant that is able to protect from free radicals and regenerate antioxidants, restoring their antioxidant capacity[viii].



Foods: almonds, sesame seeds, oats, mushrooms, soybeans


B2 is unable to be endogenously produced, meaning that it must be obtained through the diet. B2 plays a role in energy production and immune function by reinforcing the body's reserve of antibodies.



Foods: capers, chamomile tea, apples, red onion, red grapes, tomato


Quercetin has the capacity to support the body’s antioxidant potential and decrease prostaglandin E2 and leukotriene production. Quercetin may decrease susceptibility and block substances involved in allergies by acting as an inhibitor of mast cell secretion, causing a decrease in the release of tryptase, MCP-1 and IL-6 and the down-regulation of histidine decarboxylase mRNA from few mast cell lines[ix] .



Foods: beans such as Lima, kidney and lentils, spirulina, kale, spinach, lean red meat, tofu


Iron is involved in immune function as part of peroxide-generating enzymes and nitrous oxide-generating enzymes which are required for correct immune cells functioning.

*not to be consumed as a supplement during illness.


Probiotics (Pro- for and bios- life) are live microorganisms which beneficially affect the host by creating intestinal microbial balancexiMany factors, such as diet or climate, aging, medication (i.e. antibiotics), pH, infection, genetics, socioeconomic circumstances and lifestyle can upset this balance and cause disruption of the balance of the normal microflora leading to decreased resistance, colonization and to alterations in the metabolic activities of intestinal flora.

Optimal GIT function depends on a co-existence between 1014 resident micro-organisms of different species. The primary beneficial bacteria in the gut are bifidobacteria and lactobacilli; these species produce lactic acid which creates an acidic environment in the gut which inhibits pathogenic bacterial growth. These species promote the production of bacteriocins (natural antibiotics) and immune processes.

Probiotics may enhance immune response by binding to intestinal epithelial cells and inhibit the binding of pathogenic bacteria to the gut wall by stimulating production of mucus and anti-inflammatory cytokines[. Probiotics may enhance IgA levels which block offending organisms.

Effect of probiotics on the intestinal epithelium

  • Promote tight contact between epithelial cells forming a functional barrier
  • Reducing the secretory and inflammatory consequences of bacterial infection
  • Enhancing the production of defensive molecules such as mucins
  • Probiotics may alleviate digestive complaints and may influence peristalsisiv

Immune effects

  • Probiotics as vehicles to deliver anti-inflammatory molecules to the intestine
  • Enhance signaling in host cells to reduce inflammatory response
  • Switch in immune response to reduce allergyx.


Colostrum is the first lacteal secretion produced by the mammary gland of a mother prior to the production of milk. It is an active immune system designed to protect the newborn in their first weeks of life.

It is highly nutritious and is rich in vitamins, minerals, anti-microbial peptides and growth factors. It is also a good source of protein and contains all amino acids, especially glutamine, which has been shown to aid in intestinal cell health (most of our immune system is in our intestines)[xvii].

Colostrum neutralizes a diverse range of pathogens, replenishes flora and sooths gut inflammation[xviii],[xix]. Rich in immunoglobulin's (Ig) IgA and IgG; secretory IgA protects the mucous linings in the body from inflammation and pathogens (such as respiratory and intestinal tract). IgG protects against toxins, bacteria and virusesxviii.

Colostrum’s high levels of immunoglobulin’s, lactoferrin and lactoperoxidase colostrum may have potential in supporting host resistance[xx].



To enhance the immune system and the nutrients discussed earlier, it is ideal to incorporate nutrient rich fruits and vegetables into your diet that can provide synergistic benefits.

  • Oranges contain abundant levels of Vitamin C plus folate and potassium. They also possess the plant pigments rutin, hesperidin and bioflavonoids
  • Mandarins are high in vitamin C, betacarotene and potassium. They also contain pectin (a soluble fibre) which helps to control blood cholesterol levels
  • Carrots are a rich source of carotenoids, especially beta-carotene, which can be converted into vitamin A in the body. Other carotenoids include alpha-carotene, lycopene and lutein
  • Mangoes are high in betacarotene, Vitamin C and Vitamin E, whilst also being high in pectin (soluble fibre)
  • Pineapple contains significant levels of Vitamin C, A and the enzyme bromelain, which is a protein splitting enzyme that may benefit digestion.
  • Lemons have a high Vitamin C content, whilst also containing Vitamins A, B1, B2, B3 and bioflavonoids. Lemons have antiseptic and cleansing actions making them beneficial for those prone to infections and fevers
  • Limes are a good source of vitamin C and other antioxidants including ellagic acid, quercetin and kaempferol (a type of polyphenol).

Other possible beneficial inclusions:

  • Olive leaf extract
  • Maitake and shitake mushrooms
  • Garlic
  • Elderberry Extract
  • Rosehips
  • Aloe vera
  • Echinacea
  • B vitamins
  • Antioxidants- blueberries, goji berries, acai