Maintain a Healthy Immune System this Winter

Although we are one month into Winter, when it comes to immunity it is better to prevent disease than to cure it.

The immune system is a complex organ and when working optimally it is able to recognise invaders such as viruses or bacteria and mount a response via our white cells by destroying the uninvited intruders.  

So, why do more people get sick in Winter?

The majority of upper respiratory tract infections are due to viruses. The cause of the common cold includes rhinovirus (there are more than 110 serotypes), coronavirus (several types) and adenovirus and there is influenza virus (A, B & C).

In Winter, viral cell walls are more stable in cold and low humidity environments which means they are able to survive longer in the air.

As there are so many viruses that we can catch, infection with one serotype may not confer immunity against another.

Studies also show is that our resistance to infection is inherited. This is known as the ‘resistome’ and this varies from person to person.

In addition to this, there are factors that decrease host resistance to infection, such as:

  • age (infants and elderly are particularly vulnerable)
  • having a chronic disease
  • severe stress (physical or emotional)
  • prior infections
  • damaged primary defence mechanisms (burns, cuts)
  • Malnutrition/Diet
  • environmental influences (toxin exposure)

My Health Tips:

Immune support is still necessary even if you have been vaccinated for the flu. Flu vaccines do not protect against infection or illness caused by other non-flu viruses that spread during Winter. 

The majority of antibiotics are ineffective against viral infections and should not be taken. If you do require them, a supplementation of Probiotics is recommended when taking prescribed antibiotics.

Support the “Superstars” of Your Immune System

Our nutritional status has a big impact on how well we are able to mount an immune response.

Vitamin A

Vitamin A supports healthy mucosal barriers and the function of macrophages, neutrophils and natural killer cells.

Sources of Vitamin A include carrots, green leafy vegetables, spinach and sweet potatoes.

Vitamin C

Vitamin C is essential for fighting respiratory infections as it increases the number of circulating immunoglobulins involved in the immune response.

Nature provides us with an abundance of citrus fruits, broccoli and sweet potatoes in winter which are high in vitamin C and bioflavonoids (plant derived compounds) that help the absorption of vitamin C.

Vitamin D

Vitamin D is not a nutrient in the usual sense as under normal conditions as it is supplied by the action of sunlight on the skin.

The main function of vitamin D is to maintain serum calcium and phosphate concentrations by enhancing the absorption of calcium from the diet. However vitamin D helps induce monocyte conversion to macrophages (white blood cells that ingest microbial pathogens).

Few foods contain significant amounts of vitamin D2 (salmon, herring, mackerel and eggs) therefore in winter supplementation is advisable to maintain sufficient levels.


Zinc functions as a cofactor for immune dependent responses and is required for the maintenance of healthy mucous membranes.  Deficiency impairs white blood cell function: macrophages, neutrophils, NK cell and complement activity.

Food sources of zinc are beef, egg yolks, liver, oysters, sunflower and pumpkin seeds.


Iron is a trace mineral we required for cellular energy, synthesis of haemoglobin (a molecule required for oxygen transport in red blood cells) and detoxification.  For immunity it is involved in proliferation of white and red blood cells and deficiency impairs T cell function, cells that destroy virus infected cells.

Groups most at risk of iron deficiency include toddlers, children, menstruating women, vegans and vegetarians.

Best sources of iron rich foods is haem iron found in animal meats including beef, lamb liver, poultry and fish, and absorption is increased when consuming foods high in Vitamin C in the same meal (for example – tomatoes, broccoli, red and yellow capsicum).

Non-haem food sources are found in plants and they include spinach, lentils, tofu and broccoli. However, iron in these foods is not as well absorbed as in animal meats due to phytates which bind minerals inhibiting their absorption.

My Health Tip:

If you are experiencing recurrent infections get your blood levels of Vitamin D, serum Zinc and Iron levels checked.

Other Considerations for Healthy Immune Systems

Particularly when Winter is also the season to be coughed or sneezed on by your children!

  • Always maintain good hygiene practices by washing your hands frequently with soap and water for 40 seconds. Keep your hands away from your face.
  • Love your gut as over 80% of the immune system is in your digestive tract. Altered intestinal microflora may contribute to immune deficiency. Feed your commensal bacteria with prebiotic foods such as asparagus, banana, dandelion greens, endive, leek, garlic, Jerusalem Artichokes, legumes and onion. Homemade organic bone broths are rich in minerals and glycine to heal a leaky gut.
  • Kick or Manage your Stress by undertaking regular exercise, yoga or meditation. Cortisol (the hormone released from the adrenal glands when we are stressed) reduces immune responses by causing macrophage dysfunction and depleting Vitamin C.
  • Get adequate Sleep as when you are sleep deprived your body makes fewer cytokines, a protein that targets infection and inflammation. Also keep in mind that if you have been vaccinated for the flu, chronic sleep deprivation makes the flu vaccine less effective.

And Keep Doing What You Already Know!

As we all know, consuming an abundance of whole foods, especially plants, are essential for good health and well being. Aim to eat at least 5 servings of vegetables and 2 servings of fruit a day as a minimum. 

My Final Tip!

This is an Immune Boosting Decoction for adults. Take 3 cups a day for the prevention & treatment of infection.

To a cup add:

  • 5 – 10 cm piece of grated ginger rhizome
  • 2 cloves of garlic (cut in quarters)
  • A few slices of fresh chilli or a dash of cayenne pepper
  • The juice of 2 lemons
  • ½ tsp Manuka honey
  • Top with boiled water

Place a saucer over the cup and let it sit for 5 – 10 minutes. Scoop the garlic and ginger out of the cup and slowly sip while warm.

Then say cheers to a healthy Winter season!


Connect with Melisa on:

Facebook: Melisa Byrne Naturopath



This article was written for information and education purposes only and is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay seeking it because of something you have read in this article.


Melisa Byrne,


Melisa Byrne is a degree qualified naturopath, practicing from a multi modality clinic in Adelaide’s North Eastern Suburbs.  She has a special interest in gut health (IBS, Coeliac Disease, IBD, Small Intestinal bacterial overgrowth and food sensitivities), weight loss, hormone imbalances and autoimmunity.

As a busy mother of three teenage boys, she appreciates the challenges women face today with prioritising their own health alongside work, study and raising a family and therefore she has a caring and understanding approach to supporting women with their health.

Melisa is a lecturer and clinic supervisor at Endeavour College of Natural Health. She also holds regular health information sessions for the public at the clinic where she practices from and presents at various health events.