Most of us think about our immune system at exactly the wrong moment, somewhere around the second day of a head cold. By then, the choices that shape how your body responds to infection have already been made across the preceding weeks and months. The encouraging part is that the things that matter most are ordinary, unglamorous and largely within your control. This guide walks through what the evidence actually supports, and where clinical care may have a role.
TLDR
- Immune resilience is built gradually, so the months before winter matter more than the week you start sneezing.
- Health and Wellbeing Queensland identifies nutrition, movement, sleep and stress as the four factors with the greatest influence on immune function.
- Aim to get key nutrients from whole foods first, because the body absorbs them better than from supplements alone.
- Adults need 7 to 9 hours of sleep a night, according to the Sleep Health Foundation.
- A 20 second handwash with soap and water remains one of the most effective ways to stop the spread of germs.
- Annual influenza vaccination is recommended for everyone aged 6 months and over, and timing matters.
- Testing can show whether you have a nutrient deficiency, which is a very different question to whether a supplement will make you well.
Why the lead-up matters most
Your immune system is not a switch that can be flicked on when the temperature drops. It is a network of cells, tissues and organs that adapts continuously to how you eat, move, sleep and manage stress, as Health and Wellbeing Queensland describes it.
That means the habits you keep in the milder months are, in effect, your preparation. Someone who has slept well and eaten a varied diet through autumn walks into winter in a different position to someone who has not, regardless of what they take in June.
It is also worth being realistic. No habit and no treatment makes anyone immune to infection. The goal is not invincibility. It is giving your body the conditions it needs to do its job well.
How your immune system actually works
Broadly, your defences work in layers. Physical barriers such as skin and the linings of your airways and gut come first. Behind them sits the innate immune response, which reacts quickly and non-specifically, and then the adaptive response, which learns to recognise specific threats and remembers them.
A large share of the body’s immune cells reside in the gut, which is why gut health and immune function are so closely linked. This is also why advice about fibre, prebiotics and probiotics keeps appearing in conversations about immunity.
Understanding these layers explains why the advice below is so broad. Supporting immunity is less about one heroic nutrient and more about maintaining a lot of ordinary systems at once.
Eat a rainbow of nutrients
Health and Wellbeing Queensland recommends building meals around a variety of nutrient-rich foods: fruits and vegetables for vitamins, minerals and antioxidants; lean proteins for cell repair; reduced fat dairy for calcium and vitamin D; and whole grains for the fibre that supports gut health.
Prebiotics feed the beneficial bacteria in your gut and are found in onions, garlic, bananas and wholegrains. Probiotics supply those bacteria directly, through yoghurt with live cultures, kefir and fermented vegetables such as sauerkraut.
The guidance from Health and Wellbeing Queensland is to aim for these nutrients from food first, because the body absorbs them better when they arrive alongside the other compounds found in whole foods. Where a genuine gap exists, clinic-quality oral supplements can help maintain intake between meals, though they work best as a complement to a varied diet rather than a substitute for one.
Key nutrients for immune function
Several nutrients have an established role in immune function. It is important to read the table below for what it is: these nutrients are necessary for normal immune function, but taking more of them than you need does not produce better immunity.
Nutrient | Role in immune function | Common food sources |
Vitamin A | Contributes to normal immune function | Lean meats, oily fish, eggs, dairy, colourful fruit and vegetables |
Vitamin C | May reduce the duration and severity of common colds | Oranges, berries, kiwifruit, capsicum, broccoli, dark leafy greens |
Vitamin D | Contributes to normal immune function; levels commonly fall in the cooler months | Eggs, liver, oily fish, plus safe daily sun exposure |
Zinc | Important for skin, immune function and wound healing | Lean meats, fish, seafood, poultry, dairy, fortified cereals |
Prebiotics and probiotics | Support the gut microbiome, where much of the immune system sits | Onions, garlic, bananas, wholegrains, yoghurt, kefir, sauerkraut |
Vitamin C is a useful example of how evidence gets simplified. Cochrane reviews have found that routine vitamin C supplementation does not reduce how often the average person catches a cold, though it appears to modestly shorten how long symptoms last. That is a real effect, and a much narrower one than most marketing suggests.
Vitamin D is worth its own mention for Australians, because levels commonly fall over the cooler months when we spend less time outdoors and cover up. If you are unsure where you sit, functional testing and assessments can identify an actual deficiency, which is a far more useful basis for a decision than guessing.
Sleep, movement and stress
If nutrition gets most of the attention, these three quietly do a great deal of the work. They are also the areas where small, sustainable changes tend to outperform dramatic ones.
Why sleep does heavy lifting
Quality sleep is vital for a well-functioning immune system, and poor sleep weakens the body’s ability to fight off infection. The Sleep Health Foundation recommends 7 to 9 hours a night for adults, with more required for teenagers and children.
The practical levers are familiar: a consistent sleep schedule, a wind-down routine, a sleep-friendly environment, limiting screens and heavy meals before bed, and staying active during the day. None of these are exciting. All of them compound.
Moving most days each week
The Australian physical activity guidelines recommend adults accumulate 2.5 to 5 hours of moderate intensity activity each week, or 1.25 to 2.5 hours of vigorous activity, plus muscle-strengthening activity on at least two days. Moderate exercise within these guidelines may support immune function.
One caveat worth keeping. If you are already unwell, rest takes priority over training. Pushing through does not accelerate recovery.
Keeping everyday stress in check
Stress management sits alongside diet, movement and sleep as a factor influencing immune function. Chronic, unrelieved stress is the concern here rather than the ordinary pressures of a busy week.
Hydration deserves a mention in the same breath. Water helps carry oxygen to cells and supports absorption of water-soluble vitamins and minerals, including vitamin C and zinc. General guidance for adults is around 8 to 10 cups, or 2.1 to 2.6 litres, each day, though individual needs vary.
Simple habits that limit infection
Supporting your immune system is one half of the equation. Reducing how much you challenge it is the other, and hand hygiene remains one of the most effective and least appreciated tools available.
- Wash hands with soap and water for 20 seconds, which Queensland Government guidance identifies as best practice
- Wash before preparing or eating food, and after using the toilet or caring for someone unwell
- Wash after coughing, sneezing or blowing your nose
- Dry hands thoroughly with a clean towel or paper towel
- Stay home when you are unwell, which protects colleagues and household members
- Keep frequently touched surfaces clean during periods of household illness
Vaccination and planning your season
Annual influenza vaccination is recommended in Australia for everyone aged 6 months and over, and is funded under the National Immunisation Program for groups at higher risk, including people aged 65 and over, pregnant women, Aboriginal and Torres Strait Islander people, and those with certain medical conditions.
Timing matters because protection develops over roughly two weeks and wanes across the season. Australian Department of Health guidance is that vaccination should occur before the onset of the influenza season, while noting that it remains worthwhile at any point while the virus is circulating. Your GP or pharmacist can advise on the right timing for you.
This is the single most direct step in this article, and it belongs in any honest discussion of preparing for winter. No nutritional strategy substitutes for it.
Where testing and IV therapy fit
Intravenous nutrient therapy delivers fluids, vitamins and minerals directly into the bloodstream, bypassing the digestive system. It is used by people managing fatigue, dehydration, recovery from illness or surgery, and identified nutrient deficiencies, always alongside rather than instead of primary medical care.
It is equally important to be clear about the limits. Evidence that intravenous nutrients prevent infection or improve immunity in people who are not deficient is limited. IV therapy is not a substitute for vaccination, sleep, a varied diet, or advice from your GP, and it is not appropriate for everyone.
Where it can be useful is when a decision is grounded in information about your own body rather than assumption. Screening comes before any treatment plan, and where intravenous nutrient infusions are considered appropriate, they are delivered by a registered nurse in a monitored clinical environment, with telehealth review by an integrative medical practitioner where this is required.
Ready to prepare for winter?
If you take one thing from this article, make it the boring one. The months before winter are when immune resilience is built, and nutrition, sleep, movement, stress and hand hygiene are where the returns are largest. Vaccination handles the specific threat that these habits cannot.
For anyone who wants to understand their own nutrient status rather than guess at it, a starting point is a conversation with a clinician who can look at your history and your goals. IV Health Sunshine Coast offers a free 15 minute telehealth nursing consultation from its Sippy Downs clinic, with mobile visits available across the Sunshine Coast and hinterland.
Sources: Health and Wellbeing Queensland, Supporting your immune system this winter (reviewed June 2026); National Health and Medical Research Council, Australian Guide to Healthy Eating; Australian Government Department of Health, Physical activity and exercise guidelines for adults; Sleep Health Foundation, How much sleep do you really need; Queensland Government, Hand hygiene; Hemila H and Chalker E, Vitamin C for preventing and treating the common cold, Cochrane Database of Systematic Reviews; Australian Immunisation Handbook, Influenza.
This article is intended for general information purposes only and does not constitute medical advice or replace consultation with a qualified health professional. Intravenous nutrient therapy is not suitable for everyone, is not a treatment for infection, and does not replace vaccination or primary medical care. Individual results vary. Speak with your GP about what is appropriate for your circumstances.