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What is your immune system and can you boost it?

Woman in blue shirt in a cafe blowing her nose into a white tissue
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In this article, we explore how the immune system works and how it can be affected by illness, stress, and other factors. We also discuss the ways you can support your immune system and maintain good health.

What is the immune system?

The immune system is a network of cells, tissues, and organs that work together to protect the body from infections and diseases. It is the body's defence mechanism against harmful foreign substances, such as bacteria and viruses, that can cause illness.

Immune system infographic

How does the immune system work?

When the body is exposed to a foreign substance, such as a virus or bacteria, the immune system is activated to protect the body from infection and disease.

White blood cells make up a major part of our immune system. They are produced by our bone marrow and are divided into two main types: phagocytes and lymphocytes.

  • Phagocytes are white blood cells that can engulf and destroy foreign substances, such as bacteria and toxins.
  • Lymphocytes, on the other hand, release antibodies that help our bodies “remember” how to attack certain germs – in other words, they help us develop immunity.

Other important defences around our bodies include the skin, the stomach and the mucous membranes in our nose, mouth and genitals.

Causes of a weakened immune system

As you grow up, your immune system is exposed to more and more germs, and gets better at fighting them off. By the time you’re an adult, you should have a fully functioning immune system that can effectively fight a range of different infections – including those you’ve been vaccinated against.

However, some people may have a weakened immune system due to illness or medical treatment, which means they’ll be more susceptible to infection. You might have a weakened immune system if you:

  • Have HIV
  • Have cancer
  • Are malnourished
  • Are taking certain medications or receiving certain medical therapies, like chemotherapy

There are many different things that can cause your immune system to weaken, but it’s not something that happens overnight, or something that can be quickly remedied.

How is the immune system affected by stress?

Stress can affect the immune system in several ways. Chronic stress can suppress the immune system, making the body more vulnerable to infections and diseases. Stress can also cause inflammation in the body, which can impair the immune response and make it less effective. On the other hand, acute stress, such as the kind that occurs in response to a sudden threat, may actually help the ability of the immune system to fight off infections.

Can you boost your immune system?

Many vitamins, supplements and health foods claim to “boost” or “strengthen” your immune system, but this isn’t really possible. However, the opposite is true – neglecting your diet and living an unhealthy lifestyle can have a negative impact on your immune system.

Get vaccinated

The best way to take care of your immune system is to get all the routine vaccinations offered to you on the NHS. You’ll have received most of your routine vaccinations as a child, but there are some you’ll be offered as an adult too, including the COVID-19 vaccine and the flu jab. To find out which vaccinations you might be eligible for as an adult, check out this page.

How do vaccines help?

Vaccines work hand-in-hand with your immune system to build up protection against certain diseases. They do this by creating antibodies that are specially equipped to fight off those infections. Once the vaccine has “taught” your immune system how to fight off those specific infections, it can continue to do so for many years – although in some cases you may need a booster vaccine later down the line.

Book your flu jab at LloydsPharmacy

Eat a healthy, varied and balanced diet

To function properly, our bodies need a range of macronutrients and micronutrients, which are found across various food groups. In general, healthy eating incorporates lots of starchy carbohydrates and different fruits and vegetables, as well as smaller amounts of protein and low-fat dairy.

If you aren’t sure where to start with a healthy diet, check out the NHS Eatwell Guide and our healthy eating guide for more top tips. They contain lots of detailed information about what to aim for each day including calorie recommendations. The basic rule is to get plenty of variety across all the major food groups – in other words, only eating green vegetables doesn’t equate to a healthy diet.

Maintaining a diet like this should mean that you get all the nutrients you need, which in turn will support your immune system.

Consider taking supplements

Sometimes it can be difficult to keep up the kind of diet described above – especially if you’re vegan or have food allergies. While it’s best to get nutrients through your food, you can try taking supplements if you think there’s anything major lacking in your diet.

All the vitamins and minerals set out by the NHS here are vital for good general health, but there are a few which are particularly important for your immune system, including vitamin D. The NHS recommends that everyone in the UK take vitamin D supplements of 10 micrograms (mcg) between October and the beginning of March.

Other important nutrients for your immune system include:

Where possible, it’s best to try and get these nutrients in your diet, but if you struggle to do this you should speak to your GP about taking daily supplements. The recommended dosages for each of these vitamins can be found at this page.

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Spend some time in the sun

The NHS recommends that Brits take vitamin D supplements in the autumn, winter and early spring. This is because most of our “natural” vitamin D intake comes from sun exposure. During the coldest, darkest months, sunlight in the UK isn’t strong enough to generate adequate vitamin D.

In the spring and summer, however, we should be able to get enough vitamin D by spending some time outdoors each day. Of course, it’s important to do this in a safe way that doesn’t risk sunburn and skin cancer.

If you’d like to learn more about safely getting vitamin D from sun exposure, read vitamin D for different skin types and ages.

Keep up a healthy lifestyle 

A “healthy” lifestyle will look different to everyone, but there are some basic rules you should try to follow if you want to maintain your immune system and good general health:

  • Exercise regularly – that means doing at least 150 minutes of moderate intensity activity each week, as well as strengthening exercises
  • Get plenty of sleep – the average person needs around eight hours of “good quality” sleep each night
  • Quit smoking – our in-store service could help with expert advice and product recommendations
  • Cut back on alcohol

Lastly, try to practise good hygiene as this will stop you getting sick in the first place!

In conclusion, the immune system is a crucial component of the human body that protects us from infection and disease. Although you can't boost your immune system you can support it with a healthy diet, proper sleep, and regular exercise.

If you need more help on how to support your immunity, read our health and wellbeing advice, including tips for dealing with stress and help with healthy eating.