‘Boost your immune system’ has become a popular term – but is it really possible?

Certainly, when the threat of catching colds, flu or a tummy bug increases, the idea that you can somehow supercharge your natural immunity is an appealing one.

What affects the immune system?

Diet and lifestyle can impact your immune system in a number of ways and leading a busy, stressful life can affect your ability to fight off infections.

‘We know that the immune system is insulted by cigarette smoking, obesity and heavy drinking,’ says Professor Philip Calder, an expert in nutritional immunology at the University of Southampton.

‘Less healthy people will be in need of a boost to their immune system because their lifestyle may mean that it is not running as it should.’

Can you improve the immune system?

However, what is less certain is whether or not people who, on the face of it, lead a healthy lifestyle can make their immune system better than normal.

‘This is the subject of some interest - whether or not an immune system of a healthy person can be improved upon – we still don’t know if that’s true and it will be quite a hard thing to test,’ adds Professor Calder.

What does ‘boost your immune system’ mean?

Professor Ian Jones, a professor of virology at the University of Reading, argues that rather than talking about ‘boosting’ the immune system, what you want is for it to function at a normal, healthy level.

‘Some of the symptoms of illness, such as chills, sneezing or headaches, can be as a result of the immune’s system response to an invading pathogen.’

This essentially means that a ‘boosted’ or overactive immune system could make you feel unwell, worsen infections, such as a chest infection developing into pneumonia, and, in severe cases, lead to autoimmune problems.

Think about optimising your immune system instead

However, GP Dr Rob Hicks advises taking steps to ensure your immune system is working at its best.

‘You can support your immune system and get it working at an optimum level – but you can’t super charge it,’ he says.

How to optimise the immune system

Get some exercise

Studies suggest that exercise doesn’t just make you feel fitter; it can help keep you free of bugs too.

For example, scientists tracking the habits of 100 adults for three months found that those who did at least 20 minutes of exercise – enough to break into a sweat – five or more days a week halved their chance of a cold compared to those who did little or none. In fact, according to the results published in the British Journal of Sports Medicine (2010), the exercising participants had five days with a cold over three months, compared to nine days with the non-exercising participants.

One theory is that during exercise and for a few hours afterwards the number of white blood cells (forms of immune cells which help kill invading bacteria and viruses) circulating in the blood increases.

So how much exercise should you do? Professor Mike Gleeson, professor of exercise biochemistry at Loughborough University, says: ‘It needs to be regular, around five times a week, but anything that gets the heart rate up a bit, such as cycling or swimming – even brisk walking will do,’. However, doing too much exercise in a single session, over an hour and a half, can be stressful for the body, depressing your immune function for up to 24 hours.


Professor Calder advises around some of the key vitamins for supporting your immune system:

  • Vitamin C: There are quite a few studies that show that people who take vitamin C when they have a cold will make their symptoms better faster, but it won’t prevent them getting a cold in the first place.

  • Zinc: There is also similar evidence for zinc being beneficial for the immune system. However, some people think that they need to take as much zinc or vitamin C as they can, but that’s not the case.

    If you take too much zinc, you could become deficient in copper as excess zinc reduces the body’s ability to absorb copper.

  • Probiotics: Probiotics are a form of beneficial bacteria found in the gut, where 70% of the immune system is located.

    Some studies have looked at how well the elderly respond to vaccinations and it seems that probiotics can improve their immune response –  but the difference it makes is quite small.

    Elderly people are more susceptible to infections because they are more prone to nutritional deficiency or immune abnormalities. If you are a busy person or leading an unhealthy lifestyle, it may be worthwhile taking a multivitamin and probiotic to ensure your immune system is working at its optimum level.

Get an early night

A study published in the European Journal of Physiology found that the early part of sleep is especially important for good immune function. This is when immune cells such as T cells are redistributed to key points around the body.

Other studies have found that the genes that set the body clock are linked to immune function, which is why an unusually late night may leave you feeling rundown and more prone to a cold.


Eating a balanced diet that is low in fat and salt, with plenty of fresh vegetables, oily fish and moderate amounts of red meat and dairy is the basis for good health, as well as a healthy immune system.

If your diet is poor, then your immune system is not going to be working as well as it could, meaning that even a simple infection could become worse as a result.

What else can you do?

Finally, Dr Rob Hicks says, as well as the normal advice for a healthy lifestyle, there is laughter.

‘Laughter helps keep things in perspective; helps prevent a build-up of stress and stress hormones which can weaken the immune system.

‘Going from what I experience at the surgery, the people with a positive outlook who keep smiling seem to get ill less frequently.’


More on healthy living

For more advice on maintaining a healthy and active lifestyle, see our Healthy Living pages.

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Page last reviewed on 01/11/2020

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