How to keep your immune system strong this winter – according to experts

Get those winter defences ready now (Yui Mok/PA)
Get those winter defences ready now (Yui Mok/PA)

Looking to ‘boost’ your immune system to stay well this winter? In reality, optimal immune function is about a lot more than jumping on the latest superfood trend.

“As the colder weather approaches, people seek ways to protect themselves from flu or illness and oftentimes look for ‘immune boosting’ foods. However, we really are not able to ‘boost’ our immune system, but rather optimise strategies – including sleep, stress, exercise and diet – to support normal functioning,” explains registered dietitian Isabelle Fagan, from Dublin-based clinic Orla Walsh Nutrition.

“The design of our immune system is complex and influenced by an ideal balance of many factors, not just diet, and especially not by any one specific food or nutrient.”

When it comes to avoiding winter viruses, the best line of defence is to avoid spreading and catching them in the first place – by staying home if you’re ill, regular hand-washing, wearing a mask if you are vulnerable and keeping to well-ventilated spaces.

That said, there are things we can do to support our immune systems too…

Aim for a balanced diet with lots of variety

Fagan says: “Our immune system is best supported by a generally healthy, balanced and varied diet – inclusive of fruits, vegetables, lean proteins, starches (including wholegrains), milk and dairy products, and healthful fats. Diets that are limited in variety and higher in ultra-processed foods can negatively affect a healthy immune system, as we can miss out on things that keep our immune systems working properly.”

This includes staying well hydrated, getting plenty of vitamins A, C, D and E (by consuming a variety of fruit and veg), as well as protein and zinc too.

A couple standing looking at rows of vegetables in a supermarket
Stock up on plenty of veg (Chris Radburn/PA) (Chris Radburn/PA)

“Protein plays a vital role in all body functions but particularly in immunity, as it helps build and repair damaged immune cells. Protein can be found in a variety of foods, including meat, fish, poultry, yoghurt, milk, eggs, tofu, wholegrains (particularly quinoa and buckwheat),” says Fagan.

“Zinc supports antibody production, maintains skin integrity and is essential for immune cell function and signalling. Interestingly, it’s also been found to decrease the severity of the duration of illnesses. We can usually get it from pumpkin seeds, prawns, cheese, oysters, beef and crab.”

Feed your gut

“Gut health has a huge impact on immunity and we are learning so much more from research about the role of our microbiome – the metropolis of trillions of microorganisms that live in our bodies, particularly our gut microbiome,” Fagan says.

“Diet plays a vital role in determining what kind of microbes live in our gut and the variety that’s in there,” she adds. “Try to get a mix of prebiotic and probiotic foods. Think high-fibre plant-rich prebiotics – onions, garlic, asparagus, bananas, and fermented probiotics – live yoghurts, kimchi, sauerkraut, tempeh, kefir, fruits and veg.”

Check your vitamin D

Humans rely on sunlight exposure for creating vitamin D, and a lack of it can negatively impact our health. “Vitamin D is important because of our geography, being at such a high latitude means we don’t get much sun during the winter months due to the sun being low in the sky,” explains Dr Brian Flavin, Vhi national clinical director for urgent care and emergency medicine consultant.

“It is generally older people or people with vulnerabilities who are most at risk of vitamin D deficiency, and most of us have enough vitamin D stored from the spring and summer months to last us into the winter,” he says – noting we can also get it from our diets. Good sources include oily fish, eggs and fortified foods.

“If you are at risk of vitamin D deficiency, take advice from your own GP about supplements,” Flavin adds.

Savour your sleep

“Sleep plays an important role in supporting the immune system. Every individual will have a different level of sleep they require, generally between six and eight hours a night,” Flavin explains.

“A regular sleep cycle with good sleep habits (such as not using screens up to one hour before going to bed, no late-night caffeine, and sleeping in a dark room) can all support a healthy immune system.”

Keep an eye on your iron

A balanced diet should help keep iron levels robust. But many people can lack iron without realising, and you could find it harder to shake off those coughs and colds.

“Iron deficiency can be especially prevalent in women, but while often overlooked, diagnosing and treating iron deficiency is crucial,” says Dr Yuvraj Goud, a GP and head doctor at intravenous nutrition therapy providers Get A Drip Dublin.

“This is because iron is essential for red blood cell production and oxygen transport, enabling immune cells to function optimally. It’s another fundamental from a nutritional standpoint to support good immunity.”

Keep moving

Two people jogging alongside a river on a winter day
Staying active is key (Ben Birchall/PA) (Ben Birchall/PA)

While it’s tempting to stay cosied up at home when temperatures drop, staying active could help you stay well too.

“Regular physical activity boosts circulation, reduces inflammation, and enhances the body’s defence mechanisms. It also promotes overall health, making the immune system more resilient,” says Goud.

Keep stress in check

Making time to relax and recharge mentally is also key. Goud says: “In today’s society, we’re seeing a switch towards people considering health more holistically – it’s refreshing, as it’s important to consider the link between the mind and body when it comes to immunity.

“Meditation, for example, fosters a balanced mind-body connection. This inner equilibrium contributes to a more robust immune response, as stress and anxiety levels decrease. Techniques such as breathing exercises and yoga can have a profound impact. Stress weakens immunity, and so by managing it, we fortify our body’s ability to fend off illnesses.”