7 Tips For Maintaining A Healthy Immune System

Associate Professor Tom Buckley RN, PhD, has provided some tips on how to maintain a healthy immune system during this continuing COVID-19 crisis.

Associate Professor Tom Buckley RN, PhD – Sydney Nursing School, Faculty of Medicine and Health, University of Sydney and Department of Cardiology, Royal North Shore Hospital.

7 tips for maintaining a healthy immune system during this continuing COVID-19 crisis

“A healthy functioning immune system lives in a healthy body”.

The global outbreak of the COVID-19 virus has brought increased focus on the importance of protecting oneself from getting or spreading viruses or bacteria as well as increased interest on the importance of our immune system

The immune system is a collection of structures and processes within the body. It is essentially our second line defence system, after skin, that when functioning properly, identifies a variety of threats, including viruses, bacteria and parasites, and distinguishes them from the body’s own healthy tissue.

A healthy and fully functioning immune system is vital to recognise, combat and maintain health during times of increased stress and exposure to external threats, such as the COVID-19 virus.


To optimise immunity, it is critical to focus on recovery, especially to ensure adequate quality sleep.

Sufficient quality sleep increases our levels of lymphocytes, the cells that fight against intracellular pathogens, for example virus-infected cells such as flu. Reduced sleep results in increased circulating cortisol, higher inflammation and contributes to immune imbalance, making a person more susceptible to infections.

So, make sleep a priority and remember that good quality sleep rarely occurs by accident. Preparation for quality sleep really needs to start from the time you get up each morning.


To optimise immunity, nutritional approaches should focus on promoting healthy gut bacteria by consuming a balanced low processed diet and including prebiotics and probiotics from food.

A balanced diet should include some portions of plant-based foods and whole grains to get prebiotics. Fermented foods such as yogurt, and kombucha are good sources of probiotics.

Overall a good principle is to get main calories from plant based carbohydrates and natural healthy fats, and just ingest enough protein for repair and growth.  Intake of foods should include adequate portions of vegetables, especially green vegetables to optimise intake of antioxidants and immune essential vitamins. Other foods to include to help promote healthy immunity are: garlic (anti-inflammatory), mushrooms (rich in vitamin D, especially when exposed to the sun before cooking), almonds and avocado (both good sources of Vitamin E).

Alcohol intake should be moderate and not exceed guidelines of 2 units for males and 1 for females daily, so as not to depress immune function. Additionally, eating foods high in sugar may temporarily depress immunity, sometimes referred to as “putting your white blood cells into a temporary coma”. Excessive sugar can also impact on our adrenal glands, which produce the stress hormone cortisol, a known immunosupressor.


Physical activity increases circulation of the immune cells in the body, making it more likely that they can react quickly where needed in the body.

Physical activity and purposeful exercise boost the production of a type of white cells called macrophages. Macrophages are an important part of our immune system in its attempt to attack invading bacteria or virus that can trigger upper respiratory tract infections.

Additionally, exercise temporarily raises body temperature, which may have a role in preventing or reducing bacterial growth. However, keep exercise at moderate levels during this time as introducing high intensity, or vigorous exercise is not advisable due to the temporary adaptation effect on the immune system.


Stress essentially weakens the immune system. When stressed, the immune system’s ability to fight off pathogens (organisms that cause disease) is greatly reduced, making us more prone to infections.

The stress hormone cortisol can suppress the effectiveness of the immune system by lowering one of the main types of immune white blood cells, the lymphocytes.

Lymphocytes are one of two types of white blood cells whose role are to defend the body from foreign antigens and make antibodies. The other types of white cells are known as phagocytes, cells that can ingest, and sometimes digest, foreign particles, such as bacteria. A healthy immune system will have adequate number and function of these types of white cells.

Stress can also have an indirect effect on the immune system as when stressed a person is more likely to engage in unhealthy behavioural coping strategies, such as increasing alcohol intake, tobacco smoking, altered dietary patterns or start forgetting to take regular medications.

At this time when emotions are high from the uncertainty of what lies ahead, and navigating this “new normal”, not getting stressed can be easier said than done. A few stress management techniques can be:

  • staying physically active,
  • spending some time outdoors in nature,
  • maintaining social contact with family and friends when social distancing allows, alternatively using electronic means. 

It is also beneficial to introduce mindfulness and/ or meditation to your daily routine.  There are several free apps such as ‘Insight Timer’ or ‘Headspace’ which offer great guided mediation tools to help bring down stress levels.


Play and regular doses of fun keep us healthy.

Remember when we used to run around as kids and play? Research has shown that play, especially outdoor play is associated with a stronger autoimmune system, resistance to allergies and better overall health.

We all love laughing and know it always makes us feel better, but there are scientific reasons why it is good for us.  Research suggests that laughter promotes diaphragmatic breathing (diaphragm fluttering up and down at a very quick rate) necessary to create a strong negative pressure and increased flow within the largest lymphatic vessel of the body. This increased flow of lymphatic fluid, means more lymph pass through the lymph nodes, which itself means more immune cells, specifically lymphocytes, are produced. So, laughter really is good medicine!


Studies have shown that social contact and laughter have a measurable effect on immune function for several hours. This is likely a result of decreased stress hormones such as adrenaline and cortisol, which have wide-ranging effects on the nervous and immune systems. In addition, it has been shown people who were lonely tend to have greater levels of inflammation and a weaker immune response when challenged, than those not lonely. This mechanism is not fully understood but is believed to be related to expression of genes that play a role in inflammation and a decrease in expression of genes involved in antiviral responses.


Essential to optimal immunity is personal hygiene, especially hand washing. Keeping hands clean is one of the most important steps we can take to avoid getting sick and spreading germs to others.

Many diseases and conditions are spread by not washing hands with soap and clean, running water. The Centres for Disease Control and Prevention (CDC) recommend hand washing:

  • Before and after handling or eating food.
  • After sneezing, coughing or blowing your nose.
  • After shaking hands with another person.
  • After using the bathroom.
  • After touching an animal or handling animal waste.
  • After using public transportation.
  • After handling garbage.

The CDC recommends cleaning hands in a specific way to avoid getting sick and spreading germs to others. Use these five steps every time.

1.Wet your hands with clean, running water (warm or cold), turn off the tap, and apply soap.

2. Lather your hands by rubbing them together with the soap. Lather the backs of your hands, between your fingers, and under your nails.

3. Scrub your hands for at least 20 seconds. Need a timer? Hum the “Happy Birthday” song from beginning to end twice.

4. Rinse your hands well under clean, running water.

5. Dry your hands using a clean towel or air dry them.

Other hygiene strategies should include:

– maintaining a clean and dry toothbrush

– daily showers and changing all towels daily. Ideally using single use towels (ie paper towels) for hand washing is best.

– In the absence of soap and water, an alcohol-based hand sanitiser (at least 60%, better if 70% alcohol) can be effective in eliminating many bacteria and viruses.

It is also important to note that cigarette smoking, either primary or secondary smoking depresses immunity and makes the lungs more susceptible to infections. Smokers’ overall health tends to be worse, be sick more often than non-smokers, need to go to the doctor more often and are admitted to hospital more often than non-smokers, especially with viral and bacterial infections in the lungs (for example, pneumonia and influenza). Therefore, smoking not only induces cellular damage and inflammation to the lungs chronically but also serves as an immunosuppressor as well as being a risk factor for heart disease.

To read more about risk factors for heart disease click here.

So in summary, managing brain and body have never been more important than whilst we are navigating this ongoing health crisis. Eat well, mobilise as much as possible, protect sleep, keep in contact with loved ones using whatever means possible (while complying with social distancing guidelines of course) and seek opportunities to play and have some fun when and where possible. And remember most of all: “A healthy functioning immune system lives in a healthy body”.

Tom Buckley (RN, PhD) is associate professor at Sydney Nursing School, Faculty of Medicine and Health, University of Sydney and the Department of Cardiology, Royal North Shore Hospital. Tom is also Director of Research at StriveStonger and co-author of the 2019 bestselling book Matchfit; the complete manual to get your body and brain fit for work and play.