When it comes to health, prevention is better than cure, and resilience is your best protection against colds, viruses and flus this winter. Strengthening your immune system will help you build the inner resources to reduce your chances of getting sick and to minimise the severity and duration of an infection.
In this article, we’ll explore how to take a proactive approach to immune health this winter by combining foundational lifestyle habits with evidence-based strategies to help your body defend itself, recover faster, and stay resilient.
Your immune system and your health during colder weather
As the weather changes, many people believe that simply being in the cold causes illness, but the reality is a bit more complex. The cold weather does play a role, but it’s primarily how it affects your immune system that increases the likelihood of infection. Here’s how the colder months contribute to a greater risk of catching a cold or flu:
- The days are shorter in winter, which means less sunlight. Sunlight is needed for Vitamin D and melatonin production, both of which help support the immune system. Less of these vital nutrients means a reduced capacity to fight off invaders
- People tend to spend more time indoors with the windows closed, increasing the chance of breathing in air shared with others who may be carrying a virus
- The flu virus survives much better in low humidity than high humidity, and Melbourne winters are both cold and dry, perfect conditions for viruses to thrive
Our genetics add another layer of complexity. T-helper cells – the immune coordinators that first recognise viruses and bacteria – don’t respond the same way in every person. That’s why two people can catch the same bug yet have very different outcomes: one shakes it off in 48 hours, while the other wrestles with headaches, congestion and fatigue for a fortnight.
The most effective way to reduce your chances of getting sick this winter is to improve your health by strengthening your immune system. Not only will you reduce the chances of getting sick, but you will also lessen the intensity and duration of illness, allowing you to return to good health much quicker.
Building immune resilience: The four pillars of health
The four pillars of health – sleep, stress management, movement, and nutrition – underpin your body’s ability to defend itself and recover from illness. Strengthening these core areas is the most effective starting point for long-term immune health.
1. Manage stress levels
Stress can significantly compromise immune function by lowering levels of Secretory Immunoglobulin A (slgA), an antibody that plays a critical role in maintaining immune defences. Studies have shown that just 36 hours of stress can reduce slgA by up to 80%. Finding ways to reduce stress is essential for immune health.
Equally important is staying socially connected. Loneliness and isolation can disrupt your stress response and weaken immunity – particularly if cortisol patterns are thrown out of balance. Meaningful connection is more than emotional support – it’s also biochemical support for your immune system.
Tips for stress management:
- Practice mindfulness and deep breathing techniques (such as the 4-7-8 breathing method)
- Spend time with people who uplift you and make you feel safe
- Engage in activities that ground you, such as time in nature, movement, or creative hobbies
- Reduce exposure to draining or anxiety-inducing media
2. Sleep well
Adequate sleep is one of the most important factors in supporting immune function. Natural killer (NK) cells, which are a key part of the immune system’s first line of defense, are significantly compromised by poor sleep. In one study, just a single night of four hours of sleep reduced NK cells by 70% compared to eight hours of sleep.
Sleep tips:
- Establish a consistent bedtime routine to ensure better sleep quality
- Limit screen time an hour before bed to avoid the disruption of sleep hormones
- Consider relaxation techniques like reading, meditation, or taking a warm bath before bedtime
- Read our article on ways to improve sleep for more info
3. Exercise regularly
Regular moderate-intensity movement helps reduce inflammation, maintain thymic gland function (which supports T cell production), and improve the balance between “younger” and “older” immune cells. It also enhances your body’s immune surveillance and helps lower stress, which can otherwise suppress immune activity.
Short on time? Even short bouts of moderate exercise, such as a brisk 10-minute walk, can improve immune surveillance, especially in older adults.
4. Top up your nutrition
A balanced, whole-food diet is one of the most effective ways to maintain strong immunity. Nutrients like vitamin A, C, D, and zinc are essential for fuelling immune cell function, reducing inflammation, and helping your body respond to pathogens. You’ll find these nutrients in the following food sources:
- Vitamin A: Found in eggs, liver, cod liver oil, and colourful vegetables like carrots, sweet potatoes, and spinach
- Vitamin C: Abundant in citrus fruits, berries, capsicum, broccoli, and leafy greens
- Vitamin D: Found in fatty fish, egg yolks, and cottage cheese. In winter, a supplement may be needed, especially if sun exposure is limited
- Zinc: Present in seafood (especially oysters), red meat, pumpkin seeds, legumes, and whole grains
To support immune resilience, also aim to reduce foods that increase inflammation or suppress immune function, such as processed foods, refined sugars, and excess alcohol.
The four ways to improve immune health and reduce infection
Once these foundations are in place, you can take your immune health further by using more targeted strategies. Functional medicine practitioner Jabe Brown shares how immunity can be strengthened or supported in four ways:
1. Support and fuel the immune system (advanced strategy)
Once your nutritional foundations are in place, certain nutrients may be required at higher levels during winter, illness, or times of increased stress. This is where therapeutic support can be helpful.
- Protein: Essential for the production of immune cells and antibodies. Many people underestimate how much they need, especially when recovering from illness. Find out your protein needs in our essential guide to protein
- Vitamin D: Plays a central role in activating T-cells. In winter, supplementation is often necessary to achieve adequate blood levels for immune protection
- Zinc and Vitamin C: These are rapidly depleted during immune responses. Practitioner-guided therapeutic doses may support faster recovery and reduce symptom severity
If you’re unsure whether your diet meets your immune needs or whether supplementation is appropriate, speak with your practitioner.
2. Stimulate the immune system
When a virus or infection strikes, the immune system needs to be primed to respond quickly and efficiently. Certain herbs and supplements can stimulate immune function and help the body fight infections more effectively:
- Astragalus: Astragalus modulates immune function by stimulating the production of white blood cells and enhancing the activity of immune cells like macrophages and natural killer cells. It is traditionally used to prevent colds and strengthen overall immunity
- Andrographis: This herb is widely used to reduce the severity and duration of colds and respiratory infections. It has antiviral and anti-inflammatory effects, helping to strengthen the immune response and promote faster recovery
- Ginseng: Ginseng helps the immune system stay in balance – ginsenosides encourage protective cells (such as natural-killer and macrophage cells) to work efficiently, while also dialling down excess inflammation, the kind seen in severe viral infections like COVID-19. This dual action means it can both strengthen everyday defences and help prevent an over-reaction of the immune system
- Medicinal Mushrooms: Reishi, Shiitake and Maitake mushrooms modulate immunity by enhancing natural killer cell and antibody activity. One study showed that eating 5–10g of dried Shiitake daily for four weeks lifted secretory IgA and NK-cell activity in healthy adults. A small handful of dried Shiitake in soups or stir-fries is an easy food-based way to help fend off winter bugs
3. Borrow immunity from external sources
For extra immune support, you can “borrow” immunity from certain substances as they provide your body with antibodies or beneficial immune cells. This approach is particularly valuable for those with weakened immune systems. This includes:
- Propolis: A natural substance produced by bees, propolis has been shown to have antibacterial, antiviral, and anti-inflammatory properties. Propolis oral spray can significantly reduce the duration of upper respiratory tract infections. It’s commonly available as an alcohol-free extract or throat spray and can be used daily during winter or at the first sign of a sore throat- typically 2–4 sprays, up to three times per day
- Lactoferrin and colostrum: These immune-boosting compounds help strengthen your body’s defences against infections. In a 12-week study, daily supplementation with bovine lactoferrin (200 mg) reduced respiratory symptoms and improved immune cell activity. Both are available as capsules or powders, and can be taken daily or during periods of increased vulnerability
- Probiotics: Targeted strains can fortify immunity – especially when gut balance is off after antibiotics or during IBS-type symptoms. A 2022 meta-analysis found that daily doses of strains like L. rhamnosus GG and B. lactis HN019 cut cold risk and duration, likely by boosting secretory IgA and natural-killer-cell activity. Strain and dose matter, so choose products with practitioner guidance. Fermented foods like kefir, kimchi, sauerkraut and miso also supply live cultures that help diversify gut bacteria and reduce inflammation
4. Target and kill off infections
When illness strikes, it’s essential to target and neutralise the infection directly. Certain anti-viral foods and supplements can help in this process:
- Garlic: A powerful antiviral and antibacterial, garlic is most effective when eaten raw or lightly cooked, as this preserves its active compound, allicin
- Manuka Honey: Known for its antibacterial and antiviral properties, Manuka honey can be a helpful remedy for sore throats and respiratory infections
- Green Tea: Rich in polyphenols, particularly EGCG, green tea has strong antiviral properties and helps detoxify the body while supporting immune health
Incorporating warming foods into your diet can also help alleviate symptoms and support your body’s natural defences against infection. Warming foods such as:
- Ginger: Drinking ginger tea with fresh thyme or sage can help alleviate sore throats and coughs. Ginger has potent anti-inflammatory effects, while thyme and sage are antiviral and antibacterial, and good for chesty coughs
- Turmeric: Its active compound, curcumin, has potent anti-inflammatory and antioxidant effects supported by research
- Herbal Teas: Particularly green tea, which has antiviral, antifungal, anti-inflammatory, and antibacterial properties that support detoxification
These warming foods not only taste comforting but also play an essential role in supporting the immune system’s ability to combat infections during winter.
Practical tip: Don’t forget the basics – washing your hands regularly helps prevent the spread of infections. But a note of caution, keep this in balance because too much washing and sanitising leads to dry hands. Our functional medicine practitioner, Rebecca Hughes suggests replacing the oils washed away in your skin which are protective barriers to unwanted external substances, with oils like olive oil or coconut oil. This will maintain the integrity and health of your skin better than moisturisers and is especially helpful if you have eczema or psoriasis.
Your winter wellness plan
By combining these evidence-based strategies – nourishing your body with the right foods, adopting supportive lifestyle habits, and using targeted natural supports when needed – you can build a more resilient immune system that’s better prepared for winter. Instead of waiting until illness strikes, focus on daily care and prevention to stay well through winter.
And remember, you don’t have to do it alone. If you’re a patient at Melbourne Functional Medicine and would like tailored support for your immune health this season, reach out to your health coach – we’re here to help you stay well, all winter long.
