Top Tips for Keeping Colds and Flu Away This Autumn and Winter | NDS Nutrition
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Top Tips for Keeping Colds and Flu Away This Autumn and Winter
The change of season brings shorter days, cooler temperatures and the familiar return of colds, flu and respiratory bugs. Most people accept this as inevitable. It is not. The reason we get sick more in autumn and winter is not simply bad luck, it is a predictable set of biological and environmental shifts that we can actively address. Here is what actually works, and why.
Every autumn the same pattern plays out. Days shorten. Temperatures drop. People move indoors, into closer proximity with others in less ventilated spaces. Vitamin D synthesis stops. Diets shift toward less diverse, more comfort-focused foods. The gut microbiome changes with the season. And the immune system, which has been quietly operating on a summer advantage for months, begins to feel the pressure of all these changes at once.
Understanding this as a system rather than as random bad luck is the first step to doing something meaningful about it. The tips below are not generic wellness advice. They are grounded in the specific mechanisms that make us more vulnerable in the colder months, with evidence-based actions against each one.
Why we get more colds and flu in autumn and winter
Before the tips, a brief explanation of the mechanisms. Rhinoviruses and influenza viruses replicate more efficiently in cold, dry air. Research confirms that flu viruses survive longer in dry air, which is why outbreaks peak in winter when central heating desiccates our homes and workplaces. Cold air also narrows the blood vessels in the nasal passages, reducing the blood flow that delivers immune cells to the site of infection and slowing the mucociliary clearance mechanism that sweeps pathogens out of the airways.
At the same time, the biological factors that support immune competence in summer deteriorate in winter. Vitamin D synthesis stops from October in the UK. Time outdoors decreases. Sleep quality often worsens with disrupted light cycles. The gut microbiome, which houses 70 to 80% of the immune system, shifts with the change in diet and reduced physical activity. These changes compound each other, and the result is a body that encounters more pathogens at the precise moment it is least equipped to deal with them.
The tips that actually make a difference
UV-B synthesis stops in the UK from October. Begin supplementing at 1,000 to 2,000 IU of D3 daily from the start of October without waiting for symptoms. A 2024 meta-analysis of 25 RCTs confirmed an 11% reduction in acute respiratory tract infection risk from supplementation.
The UK Health Security Agency found that regular ventilation reduces virus transmission in enclosed spaces by up to 50%. Opening windows for 10 minutes every hour when indoors clears viral particles without meaningfully affecting indoor temperature.
Proper technique, 20 seconds minimum, covering all surfaces including between fingers, under nails and the backs of hands, reduces respiratory infection risk by 16 to 21%. Most people wash their hands for less than 8 seconds. Frequency without technique adds little protection.
70 to 80% of the immune system resides in and around the gut. Strain-specific probiotic supplementation beginning in September or October means the gut microbiome shifts that support immune competence are established before the peak of the respiratory virus season arrives.
A single night of poor sleep measurably reduces immune cell activity. People who sleep fewer than six hours are significantly more likely to develop a cold when exposed to rhinovirus than those sleeping seven or more hours. Sleep is not a lifestyle preference. It is immune infrastructure.
Regular moderate aerobic exercise boosts the circulation of immune cells and is one of the most consistent immune interventions in the literature. High-intensity exercise sustained beyond 90 minutes temporarily suppresses immune function. Moderate, consistent movement is the target.
Vitamin D - the single most impactful seasonal change you can make
The evidence on vitamin D and respiratory infection prevention is now substantial enough that the NHS recommends supplementation for all UK adults from October through March. The recommended government dose is 10 micrograms (400 IU) daily, which prevents clinical deficiency. The dose associated with meaningful immune benefit in clinical research is higher, typically 1,000 to 2,000 IU of D3 daily for otherwise healthy adults.
Around 18% of UK adults aged 19 to 64 are deficient in vitamin D, with rates rising significantly in older adults and those with darker skin tones. The 2025 UK Biobank study of 36,258 participants found that those with severe vitamin D deficiency had a 33% higher rate of hospitalisation for respiratory tract infection than those with adequate levels. For each 10 nmol/L increase in serum vitamin D, the hospitalisation rate fell by 4%.
The form of vitamin D matters: vitamin D3 (cholecalciferol) is the form the skin produces and is significantly more effective at raising and sustaining serum 25(OH)D levels than D2 (ergocalciferol). Food state vitamin D3, presented within a whole food matrix alongside the cofactors that support its absorption and utilisation, is processed more effectively than isolated synthetic D3. Take it alongside your fattiest meal of the day, as vitamin D is fat-soluble and absorption is meaningfully higher with dietary fat present.
Your gut is your first line of immune defence
The idea that immunity begins in the gut is no longer a fringe position. It is basic immunology. The gut-associated lymphoid tissue houses the majority of the body's immune cells, and the composition of the gut microbiome directly shapes how effectively those cells respond to respiratory pathogens.
Autumn typically brings a shift in diet toward less fresh produce, more processed comfort foods and less diverse plant intake. These changes reduce the Bifidobacterium and Lactobacillus populations that are central to immune regulation, reduce short-chain fatty acid production that maintains gut barrier integrity, and increase the background inflammatory load that diverts immune resources away from pathogen defence.
Starting targeted probiotic supplementation in September, before the respiratory virus season peaks, gives the microbiome shifts that support immune competence time to establish. A Cochrane systematic review confirmed that Lactobacillus and Bifidobacterium strains reduce both the incidence and duration of acute upper respiratory tract infections. The effect is not dramatic but it is consistent, and it builds over weeks of daily supplementation rather than appearing overnight.
The foods that support seasonal immune resilience
No single food prevents colds. But the nutritional environment the immune system operates in determines how well it responds when challenged. The following foods have the strongest evidence base for supporting immune function specifically in the context of respiratory infection risk.
Salmon, mackerel and sardines provide dietary vitamin D alongside EPA and DHA, which modulate the inflammatory response to infection. Two portions a week is the target.
Kefir, natural yoghurt, sauerkraut and kimchi deliver live Lactobacillus populations directly to the gut, supporting the microbiome diversity that underpins mucosal immune defence.
Spinach, kale and dark cabbage provide vitamin C alongside folate, which supports white blood cell production. Cooking briefly preserves most of the nutrient content while improving digestibility.
Allicin in garlic has documented antimicrobial properties. Ginger contains gingerols with anti-inflammatory effects. Both are easy to incorporate into autumn soups and stews.
Pumpkin seeds, chickpeas and lentils provide zinc, which is essential for immune cell development and the inflammatory response. Zinc supplementation reduces cold duration when taken within the first 24 hours of symptom onset.
The diversity of plant foods in the diet directly correlates with gut microbiome diversity. Aim for 30 different plant foods per week. Variety matters more than volume of any single food.
Sleep - the immune intervention most people undervalue
Sleep is the primary window for immune regulation, inflammatory clearance and the production of cytokines that coordinate the immune response. It is not a recovery tool. It is an active biological process that the immune system depends on.
Research has demonstrated that people sleeping fewer than six hours per night are significantly more susceptible to developing a cold when exposed to rhinovirus than those sleeping seven or more. A single night of poor sleep reduces natural killer cell activity, the front-line immune cells that identify and destroy virus-infected cells, by a measurable amount. Chronic sleep restriction, the kind that accumulates over weeks of moderately short nights, progressively impairs the immune response in ways that compound over time.
The practical implication for autumn is that as routines change with the return of school and work demands, protecting sleep duration and quality is a direct immune investment. Consistent sleep and wake times, a cool and dark bedroom, limiting screen exposure before bed and avoiding caffeine after early afternoon are the interventions with the strongest evidence base. None of them require a supplement.
Managing stress before it suppresses your immunity
Cortisol, the primary stress hormone, has direct immunosuppressive effects at the concentrations produced by chronic stress. It suppresses natural killer cell activity, reduces the production of secretory IgA (the primary antibody in mucous membranes that provides the first line of defence against inhaled pathogens), and alters the gut microbiome in ways that reduce populations of beneficial bacteria.
The return of demanding schedules in September and October coincides with the start of the respiratory virus season. Practical stress regulation strategies with evidence behind them include regular physical activity, time outdoors even in colder weather, adequate social connection, and consistent sleep. These are not soft wellness recommendations. They are direct interventions on the cortisol-immunity axis that determines how robust the immune response to seasonal pathogens will be.
What the evidence says about popular remedies
Building the habit before the season peaks
The most important point about all of the evidence-based interventions above is that they require lead time. Vitamin D takes weeks to raise circulating levels meaningfully. Probiotic supplementation takes 8 to 12 weeks to produce the gut microbiome shifts that support immune competence. Sleep debt cannot be recovered in a night. Stress cannot be managed in a weekend.
The peak of the UK respiratory virus season is typically November through February. Starting the interventions described in this article in September or early October means the biological changes they produce are established before the viral challenge is at its most intense. Starting in December, once the season is already underway, is still worth doing, but it is starting from a deficit.
Frequently asked questions
Is it too late to start if it is already October or November?
No. Starting later is still significantly better than not starting. Vitamin D supplementation begins to affect circulating levels within two to four weeks. Probiotic benefits on mucosal immune function begin appearing within two to four weeks as well, with fuller effects building over two to three months. Every week of consistent supplementation and sleep improvement adds to your resilience through the season.
Do I still need to supplement with vitamin D if I go outside every day?
Yes, if you are in the UK between October and March. The angle of the sun between these months means UV-B radiation is insufficient to trigger meaningful cutaneous vitamin D synthesis at UK latitudes, regardless of how much time you spend outside. Sun exposure on a bright winter day in the UK produces negligible vitamin D. Supplementation is necessary to maintain adequate levels throughout autumn and winter.
Can I take vitamin D and probiotics alongside each other?
Yes, and the evidence suggests their combination is superior to either alone. Research has confirmed that specific probiotic strains increase vitamin D receptor expression in the gut mucosa, enhancing the immune effects of vitamin D, while vitamin D in turn amplifies the anti-inflammatory and immune-modulating effects of probiotic strains. The two work through complementary mechanisms and are more effective together than individually.
What is the difference between a cold and flu, and does it change what I should do?
Influenza produces a more severe and sudden onset illness with fever, muscle aches and systemic symptoms. Colds are typically milder with nasal congestion and sore throat as the primary presentation. Over 200 different viruses can cause cold-like symptoms. The preventive strategies described in this article reduce susceptibility to both. For influenza specifically, vaccination provides an additional layer of protection and is recommended from early October before the flu season peaks.
How much sleep do I actually need to support my immune system?
Seven to nine hours is the evidence-supported range for most adults. The research on immune function specifically shows a clear threshold effect at around six hours: people consistently getting fewer than six hours have significantly higher susceptibility to cold viruses. Seven hours appears to be the minimum for adequate immune function; eight is associated with better outcomes across most health markers. Quality matters as well as quantity. Fragmented sleep is less immunologically restorative than uninterrupted sleep of the same duration.
The autumn transition is not something to wait out. It is a predictable set of biological changes that respond to predictable interventions. Start with vitamin D, protect your sleep, support your gut and keep moving. The season does not have to mean months of colds.
Sources: UK Health Security Agency - ventilation and virus transmission data; Bournot et al. (2025) Vitamin D status and respiratory tract infections, UK Biobank 36,258 participants; Meta-analysis 25 RCTs, vitamin D and acute respiratory tract infection risk, Public Health Nutrition (2024); Cochrane Database of Systematic Reviews (2022) Probiotics for preventing acute upper respiratory tract infections; The Online GP - Winter Illnesses 2025: evidence-based prevention; Science Focus (2025) 4 proven rules to avoid getting sick in winter; Examine.com - Supplements for cold and flu, evidence ratings; NHS vitamin D guidance October to March; Boots Superintendent Pharmacist Claire Nevinson, autumn immune tips (September 2026); Midland Health - Staying healthy through cold and flu season (2025); Anahad O'Connor (2010) - rhinovirus sleep susceptibility research.