In the age of Covid-19, ensuring a healthy immune system is more important than ever.
It’s common for our immunity to feel weakened in the cold winer months. For one thing, some infractions, such as the flu virus, thrive in colder temperatures.
Meanwhile, a study by scientists at the University of Cambridge found that our immune systems vary season-to-season, with certain conditions aggravated in the winter.
Thankfully, there are ways you can take action to ensure good immunity this winter - and, as is often the case when it comes to wellbeing, the best place to start is with your diet.
From upping your intake of immunity-boosting foods and helpful supplements to lifestyle changes you can make, below we detail seven easy ways to improve your immunity this winter.
1. Top up your vitamin D
Vitamin D tops our list of the best vitamins for women over 50, but in truth it is an essential vitamin for everyone - particularly in winter.
If vitamin D levels are low, a vital part of the immune system – the TR7 receptor – doesn’t work as well. TR7 helps defend us against viruses, especially those of the respiratory system, such as coughs, colds and flu, according to researcher Dr Victor Martinez-Taboada of the Universidad de Cantabria.
Our primary source of vitamin D is made from sunshine, which can make for bad news in the darker months. And, with Covid-19 confining many of us to our homes, vitamin D deficiency is increasingly common.
The US health department advises anyone who can’t get enough vitamin D via sunlight to top up their levels by either eating more vitamin D foods or taking a supplement. Meanwhile in the UK, the NHS advice is that everyone over the age of four should consider taking a daily supplement containing 10 micrograms of vitamin D between October and March.
On a related note, vitamin D deficiency can also be a contributing factor in seasonal affective disorder (SAD), a form of depression that's common in the colder, darker months, and often (somewhat dismissively) labelled the winter blues.
The best SAD lamps (also known as light boxes) can help combat SAD by mimicking outdoor light to increase the level of happy hormone serotonin in the body.
2. Eat more eggs
Vitamin A is vital for immunity. It helps repair mucus membranes – our first barrier against viruses – while immune cells need it to function.
Most of us make about half of our vitamin A from a nutrient called beta carotene, found in fruits and vegetables, but Dr Georg Lietz at Newcastle University has found that 30-40% of people in the UK have gene types that mean they can’t do this conversion.
“This could have a major impact on vitamin A status and immunity,” he says.
The solution? Eat foods that contain preformed vitamin A that doesn’t need conversion. Eggs are a great example, with other sources including cheese, milk and liver.
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3. Drink sensibly
“Alcohol changes the way the immune system behaves – and these changes may impair the person’s ability to fight off things like flu,” says Professor Gyongyi Szabo from the University of Massachusetts.
In fact, she found that when exposed to the equivalent of one-and-a-half large glasses of wine, immune cells produce only a quarter of a substance that normally kills invading bugs.
Take action by trying not to exceed one large glass a day, and balance boozy occasions with alcohol-free days.
4. Eat more mushrooms
Put an extract of the humble button mushroom in a test tube with immune cells called natural killer cells and their activity dramatically increases, say the researchers behind a study published in the Journal of Nutrition.
It’s believed that ingredients called polysaccharides found in mushrooms fuel these reactions.
Happily, you don’t even need to splash out on expensive ‘fancy’ mushrooms to benefit - in trials at Arizona State University, 3.5oz (100g) of button mushrooms was enough to trigger the greatest immune-boosting response.
5. Get more beta-glucans
Possibly the most important immunity boosters you’ve never heard of, there are hundreds of trials looking at the impact of beta-glucans on the immune system.
Beta-glucans are sugar molecules that appear in cell walls of certain plants and other substances. Different beta-glucans do different things – some of those in oats lower cholesterol, and those found in baker’s yeast and fungi act on immunity-priming cells to attack infections more quickly.
Our diet used to be high in them because food wasn’t so ‘perfect’. Those dark marks you used to see on fruit and vegetables? They were packed with beta-glucans, and more used to be left in bread. Now it’s harder to get them naturally.
Good natural sources include mushrooms (yes, them again!), particularly shiitake mushrooms, along with oats, which contain one of the immunity-boosting strains. Or try a supplement such as Immiflex.
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6. Live in the moment
Stress is a known immune suppressor and since we often can’t change the causes, the best antidote is to change your own response to events.
Mindfulness is one technique that has been shown in studies to strengthen the immune response. “We’ve seen changes in the killing ability of immune cells in people who practise the technique,” says Dr Carolyn Fang from the Fox Chase Cancer Center.
One place to start could be learning how to meditate, whilst mindful practices such as yoga can also help. If you fancy giving the latter a go, take a look at our pick of the best yoga mats to help you get started.
7. Reduce your sugar intake
“Sugar slows down your immune system, so it’s best avoided during cold season,” says nutritionist Gareth Zeal.
In fact, studies from California’s Loma Linda University found that within one hour of eating 100g of sugar (and that can be in seemingly healthy forms such as honey, not just cakes or biscuits), your immune defences slow and your white blood cells lose the ability to fend off bacteria and viruses.
One simple way to keep your sugar intake minimal is by having small, frequent meals containing protein to help keep your blood-sugar level stable and eliminate your body’s craving for a quick sugar fix.
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