We live in a time when there’s a vaccine, medication or treatment strategy for almost every illness. But keeping your immune system — your body’s natural defence against illness and infection — in strong shape can make all the difference. A well-supported immune system helps you fend off colds, flu and other bugs more easily. The best part? There are plenty of simple, natural ways to give it a boost.
How the immune system works
Your immune system is made up of “multiple layers of defence,” says family medicine physician Dr Julia Blank. These include physical barriers like your skin, cilia (tiny hair-like structures) that line your airways, and specialised cells that recognise and attack foreign substances such as viruses and bacteria.
“Some of these immune cells are nonspecific and destroy anything that appears foreign. Other cells produce antibodies that recognise and target protein markers (called antigens) on the surface of germs,” Dr Blank explains.
Your immune system also has memory. It can recognise pathogens you’ve come across before and respond quickly to stop you getting sick. “This is why we don’t usually get sick after being exposed to a germ we’ve already encountered and fought off in the past,” Dr Blank says.
How to boost your immune system naturally
“Maintaining a healthy immune system means taking good care of your body,” says Dr Blank. These simple strategies will help strengthen your defences and support overall wellbeing.
1. Sip alcohol in moderation.
Too much alcohol can suppress immune function, explains dietitian and health coach Jessica Cording. It’s also dehydrating and hydration is key to keeping your body resilient against illness. When you’re dehydrated, your cells don’t function at their best, leaving you more vulnerable to infection.
If you don’t want to skip a glass altogether, stick to moderation. In Australia, the National Health and Medical Research Council (NHMRC) advises no more than 10 standard drinks per week, with no more than four in a single day.
2. Curb your stress levels.
Stress might feel harmless once it passes, but chronic stress takes a real toll. “Ongoing stress can compromise or suppress the immune system and make us more vulnerable to infection,” says Dr Blank.
Consistently high stress triggers a release of cortisol, a hormone that fuels inflammation and weakens immune defences. It can also interfere with your white blood cells’ ability to fight off infection. Simple daily habits like mindfulness meditation, journalling or a walk in nature can help dial it down.
3. Enjoy plenty of fruits and vegetables.
Loading your plate with a rainbow of fruits and vegetables is one of the easiest ways to give your immune system a lift, says dietitian Beth Warren. “Fruits and veggies provide antioxidants your body needs to fight oxidative stress, which includes sickness,” she explains.
In Australia, the recommended intake is at least five serves of vegetables and two serves of fruit each day. Think leafy greens, capsicum, citrus, sweet potato and berries to get the most immune-supportive benefits.
4. Increase your intake of vitamin D.
Vitamin D is a powerhouse nutrient that supports the immune system by helping the body produce antibodies to fight off illness, explains dietitian Jessica Cording.
“Active vitamin D gets sent to different parts of the body, including your bones, intestines, brain, and immune cells, where it binds to receptors and switches them on,” adds registered dietitian Beth Warren.
The catch? Many Australians don’t get enough. While our main source is sunlight — which is why it’s often called the “sunshine vitamin” — factors like spending more time indoors and wearing SPF mean deficiency is common here too. You can also top up with foods rich in vitamin D, such as oily fish, eggs (yolks included), mushrooms, and fortified products like some plant-based milks. If you’re concerned your levels are low, your GP can do a blood test and guide you on whether a supplement is necessary.
5. Prioritise sleep time.
Good quality sleep is one of the most underrated immune boosters. “Getting enough sleep helps our bodies recover from daily physical and mental stress and supports stronger immune function,” says Dr Blank.
When you skimp on sleep, your body produces fewer protective proteins called cytokines, which help your immune response fight infection and inflammation.
Australian guidelines recommend adults aim for seven to nine hours per night, while those aged 65 and over should target seven to eight hours. A consistent bedtime routine and limiting screens before sleep can help make those hours count.
6. Wash your hands frequently.
It might sound simple, but regular handwashing is one of the most effective ways to stop germs in their tracks. “This reduces the variety and number of germs we’re exposed to and keeps our immune system from becoming overloaded,” explains Dr Blank.
The Australian Department of Health recommends scrubbing with soap and water for at least 20 seconds — about the time it takes to hum Happy Birthday twice. Alcohol-based hand sanitiser (at least 60% alcohol) is a handy back-up when soap and water aren’t available.
7. Move your body every day.
Exercise doesn’t just strengthen your muscles — it strengthens your defences too. Regular movement helps clear bacteria from the lungs and airways, lowering the risk of colds, flu, and other respiratory infections.
It also improves circulation, which allows antibodies and white blood cells to travel more effectively throughout the body, so they can detect and respond to infections faster. You don’t need to smash a HIIT workout every day to reap the benefits. A brisk walk, a yoga flow, or cycling to work all count. The key is consistency — finding ways to weave movement into your daily life.
8. Quit smoking.
We already know smoking is one of the most damaging habits for overall health, but it also weakens the immune system directly. “Smoking can cause direct damage to immune defences,” says Dr Blank.
It paralyses the tiny cilia — the hair-like structures in the airways that help sweep out bacteria and viruses. When these are immobilised, pathogens get a free pass into the lungs, which explains the higher rates of coughing, infections, and respiratory illness in smokers.
The good news? The immune system bounces back faster than you think. Research shows many of the negative immune effects begin to reverse almost immediately after quitting. Within weeks, the body’s natural defence systems start functioning more effectively, giving you stronger protection against illness.
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