Winter Immunity: Your Guide to Staying Healthy This Winter
The clocks have gone back, November is upon us, and Storm Austen has blown through. No doubt there is plenty more challenging weather to come as we head properly into winter.
As coughs, colds and other respiratory infections become more common, it's tempting to reach for supplements promising to boost our immunity. But what actually works?
Here GP Dr Vicky Carre looks at the evidence and shares her top five tips for staying healthy this winter
1. Vitamin D: Our Winter Essential
If you ask people which vitamin they associate with supporting the immune system during winter, most will probably say vitamin C. But there is another vitamin that perhaps deserves even more attention at this time of year: vitamin D.
Vitamin D is essential for maintaining healthy bones and muscles, and it also plays an important role in the normal functioning of our immune system. Our bodies produce it when ultraviolet B (UVB) rays from sunlight reach the skin. The problem is that, at Guernsey's latitude, sunlight is too weak for our skin to produce meaningful amounts of vitamin D during much of the winter. From October through to early spring, we become much more reliant on dietary sources and supplements. We can obtain vitamin D from oily fish, egg yolks and some fortified foods, but it can be difficult to get enough from diet alone.
UK public health advice for most adults is to consider taking a daily vitamin D supplement containing 10 micrograms (400 IU) throughout autumn and winter. Some people, including those who spend little time outdoors and people with darker skin, may need supplementation throughout the year, while those with diagnosed vitamin D deficiency may need higher doses.
Vitamin C is indeed important for normal immune function but contrary to popular opinion, taking large doses is not a guaranteed way to avoid a cold. Evidence from Cochrane reviews suggests that taking vitamin C regularly may modestly shorten the duration of a cold, but it does not meaningfully reduce the likelihood of catching one. Starting vitamin C once symptoms have appeared has not shown any consistent benefits for either duration or severity.
So, whilst vitamin C certainly has a role in a healthy diet, it is not the miracle cold remedy it has sometimes been marketed as. For most people, a varied diet containing plenty of fruit and vegetables should provide what they need without the need for additional supplements.
2. Fresh Air: Indoors and Outdoors
When the weather turns cold, it is natural to shut the windows, turn up the heating and shelter inside. Unfortunately, this might create an indoor environment in which air quality can cause us problems.
Firstly, respiratory viruses spread more easily. Poorly ventilated rooms allow airborne particles released when people breathe, speak, cough and sneeze to accumulate. Secondly, condensation, damp and mould can become more noticeable. Damp buildings and mould can aggravate respiratory symptoms, particularly in people with asthma. Thirdly, there is increased exposure to indoor allergens. We often associate allergies with spring and summer, but allergic symptoms can persist throughout the year. House dust mites are an important cause of perennial allergic rhinitis, while moulds and fungal spores can also trigger symptoms in susceptible people. For those with allergies to animal dander, there may be increased exposure in winter as both you and your pets cuddle up indoors more! And finally, there is an increasing awareness of the ill effects of particulate matter from open fires and wood burning stoves.
There are several simple ways to make your indoor environment healthier. Ventilate your home regularly by opening windows when practical, even for short periods, and use extractor fans in kitchens and bathrooms. Address persistent damp and condensation, and ensure that laundry is dried with adequate ventilation.
And remember that not every winter sniffle is a cold. If you have persistent sneezing, a runny or blocked nose, itchy eyes or symptoms that seem to recur in particular environments, it is worth considering whether an allergy might be responsible. If symptoms are prolonged, recurrent or affecting your sleep and quality of life, an allergy assessment may be helpful.
And do get outside every day to enjoy a blast of fresh air, even if it is only for a short walk around the block.
3. Cold and Flu Remedies: Keep It Simple
Walk into any pharmacy in winter and you will find an impressive array of expensive products promising to fight off colds and boost immunity. But do they work?
Echinacea is widely marketed for preventing and treating the common cold. Unfortunately, studies have used different preparations, doses and combinations, making the evidence difficult to interpret. Some studies suggest a possible benefit in certain circumstances, but there is no convincing evidence of a consistent, clinically meaningful preventive effect. It can also cause allergic reactions, particularly in people who are sensitive to plants in the daisy family.
Zinc is essential for normal immune function, and zinc lozenges have attracted interest as a potential treatment for the common cold. Some studies suggest that particular zinc lozenges, taken early in an infection, may shorten symptoms. However, the evidence is uncertain, results vary considerably between studies, and side effects such as nausea and an unpleasant taste can occur. There is no good reason for most people to take zinc routinely to prevent colds if they already have an adequate dietary intake.
Garlic is a great ingredient in a healthy diet, but the evidence that garlic supplements prevent or treat the common cold is limited and insufficient to support a confident recommendation. Enjoy it in your cooking, by all means, but do not rely on garlic supplements as a proven way to avoid winter infections.
What about over-the-counter cold medicines?
For most uncomplicated colds, the basics remain the most useful: paracetamol for fever, headaches and aches and pains; plenty of fluids; and adequate rest and sleep. Saline nasal sprays or rinses may also help relieve nasal congestion.
Decongestants require a little more caution. Oral decongestants such as pseudoephedrine can raise blood pressure and heart rate and may not be suitable for people with high blood pressure, heart disease or certain other conditions. They can also interact with other medicines, so check with a pharmacist before taking them. Be particularly careful with combination cold and flu preparations, which may contain several active ingredients.
Decongestant nasal sprays can provide short-term relief, but prolonged use can cause rebound congestion, making the blocked nose worse. Follow the product instructions and do not use them for longer than the recommended period, usually five to seven days.
Most colds improve within one to two weeks. Seek medical advice if symptoms worsen significantly, you develop breathlessness or chest pain, you have a persistent high temperature, or you are concerned about your symptoms. Groups at increased risk of complications, such as immunosuppressed people, older adults or those with chronic lung conditions, should have a lower threshold for seeking advice.
The bottom line? There is no proven supplement that reliably prevents the common cold. Save your money on products making extravagant claims and focus on the basics.
4. Get Immunised: One of Our Best Defences Against Serious Infection
If there is one practical step worth prioritising before winter gets into full swing, it is checking that you and your family are up to date with the vaccinations recommended for you.
Vaccines train the immune system to recognise specific infections and respond more effectively when we encounter them. They do not prevent every infection, but they can substantially reduce the risk of serious illness and complications.
Three vaccinations deserve particular attention during the winter months: influenza, COVID-19 and respiratory syncytial virus (RSV).
Flu vaccination is offered to a wide range of people at increased risk of severe illness. In Guernsey, this includes adults aged 65 and over, children aged two and three, school-aged children from Reception to Year 11, pregnant women, people aged six months to 64 years in clinical risk groups, care home residents and carers. Flu is not simply a bad cold. It can cause a sudden fever, marked muscle aches, headaches and exhaustion, and can lead to pneumonia, hospital admission and, in some cases, death. Annual vaccination is recommended because the influenza virus changes from year to year.
COVID-19 vaccination is offered to adults aged 75 and over, residents in care homes, and people aged six months to 74 years with a weakened immune system who meet the eligibility criteria. COVID-19 continues to circulate and can cause serious illness, particularly in older adults and those who are immunosuppressed. Seasonal vaccination helps maintain protection against severe disease. In many circumstances, flu and COVID-19 vaccinations can be given at the same appointment.
RSV vaccination protects against respiratory syncytial virus, a common cause of respiratory infections that can be particularly serious in young babies and older adults. In infants, RSV can cause bronchiolitis, leading to breathing difficulties and feeding problems, while in older adults it can cause pneumonia and other serious respiratory complications. RSV vaccination is offered to pregnant women from 28 weeks of pregnancy to help protect their newborn baby through antibodies passed across the placenta. It is also offered as a single, one-off vaccination to everyone aged 75 and over.
Call the surgery to check your eligibility and arrange any recommended vaccinations before winter respiratory infections become more widespread. Vaccination is one of the most effective ways to reduce the risk of serious illness.
5. Eat for Health: Keep Your Diet Colourful and Varied
It is easy for our diets to become less varied in winter. We may gravitate towards stodgier comfort foods, snack more and eat fewer fresh fruits and vegetables.
We rely on a good supply of nutrients, especially antioxidants, to support normal immune cell function. Supporting the gut microbiome is also important for a healthy immune system. The gut microbiome is a vast community of microorganisms in our lower bowel, with important roles in digestion, metabolism and interactions with our immune system. Diet is one of the key factors that influences the composition and activity of the gut microbiome, with fibre playing a particularly important role.
One of the easiest ways to get both antioxidants and fibre is to eat a rainbow of fruit and vegetables. Different coloured plant foods provide a variety of fibre, vitamins, minerals and other beneficial compounds that help support our health and the gut microbiome.
Excellent winter options include carrots, parsnips, swedes and beetroot; Brussels sprouts, broccoli, cabbage and kale; red cabbage and squash; and seasonal fruits such as apples, pears and oranges. Beans, chickpeas, lentils, oats, wholegrain bread, nuts and seeds are also valuable sources of fibre and other nutrients.
Try to include a wide variety of plant foods, aiming for at least five varieties a day and 30 varieties across the week, with every colour of the rainbow represented.
It is also worth remembering that sleep and stress management contribute hugely to overall health. Winter can be demanding on both our physical and mental wellbeing, so give yourself permission to slow down when you need to.
We cannot control the weather, and we cannot avoid every winter virus. But by maintaining a healthy routine through the winter months, we can give ourselves a better chance of staying healthy and feeling our best throughout the season.
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