As cold and flu season begins, it’s time to start paying a little extra attention to your immune system. As your body’s built-in defense against harmful bugs, bacteria, toxins and viruses, our immune system works all day, every day to keep us safe from illness.

Although our immune system works on autopilot and can’t be ‘boosted’ or supercharged through one specific nutrient or food type alone, a series of healthy habits can help it to function optimally all year round. Modern lifestyles leave many of us lacking when it comes to doing what we need to stay healthy and strong enough to fight off infections and viruses that often come out way during winter months.

Here we’ve shared the six vital nutrients to focus on in order to maintain a healthy, well-functioning immune system – with tips and tricks to help you get an extra boost this winter season.

Vitamin C

We’ve all heard that loading up on citrus fruits can help us prevent (or push through) the cold or flu – but actually it’s the vitamin C content in oranges, lemons, grapefruits and limes that is the key to better immune health.

According to numerous studies, intake of vitamin C can help to prevent infections or shorten the length of time we are sick. There are plenty of other sources of Vitamin C you can try besides citrus – including kale, spinach, papaya and peppers. You can also source good quality supplements if you struggle to obtain enough vitamin C from your diet (although as this vitamin is so abundant, most people should have no problem doing so).

Vitamin D

Most people know vitamin D as the vitamin we get from the sun – so it’s easy to see why levels often dip during winter when we are exposed to a lot less natural light. But vitamin D is one of the most important and powerful nutrients supporting our immune systems – so it’s vital to keep levels topped up throughout the colder, darker months.

Great sources of vitamin D include fish such as salmon, tuna and mackerel, as well as fortified foods such as cereals, juices and milks (just be sure to opt for minimally processed products). Vitamin D supplements might be necessary if you can’t obtain sufficient amounts from your diet – something many people struggle with.


Zinc directly interacts with the renewal process of our immune cells, helping to form healthy new ones and keep our protection high. Zinc is found in a number of foods including seafood, poultry, chickpeas and yoghurt.


Selenium is particularly powerful when it comes to the function of the immune system – specifically when it comes to preventing infections. Although animal products are amongst the best sources of selenium, Brazil nuts are incredibly high in this mineral, offering more than 100% of our daily intake in just one small serving.


Iron is important because it helps the body carry oxygen to our cells, which means it has a crucial role to play in the function of our immune system. There are two types of iron – heme iron, found in animal products, is more easily absorbed by the body. You can find heme iron in foods such as red meat, chicken, seafood and turkey. The plant-based form of iron can also be found in kale, broccoli, some beans and fortified foods.

Pro- and prebiotics

Good gut health holds the key to optimal health and wellbeing in all areas – but especially when it comes to the immune system. Without a healthy balance of gut bacteria, our immune system can’t function optimally – so taking pre- and pro-biotics or including foods rich in healthy bacteria in our diet on a daily basis is key. On top of this, one Harvard study revealed that probiotics secrete protective substances in the gut which ‘prevent pathogens from taking hold and creating major disease’.

A balanced diet is the key to a healthy immune system

What most of us miss day to day is how remarkable our in-built protection against infections and viruses is – we only truly appreciate our immunity and health when we are sick. But if we can focus on achieving a healthy, balanced diet most of the time, we can properly support our body’s natural defenses against illness, especially during winter months.