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

Certainly at this time of year 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.

Diet and lifestyle can impact on your immune system and leading a busy, stressful lifestyle can impact on 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.

‘It’s these less healthy people who are in need of a boost to their immune system because their lifestyle may mean that their immune system is not running as it should.’

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.

Why it might not be a good idea

Some people argue that supercharging the immune system is not a good idea anyway.

‘To talk about boosting the immune system is not really appropriate – you want your immune system to function at a normal level,’ says Professor Ian Jones, a professor of virology at the University of Reading.

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

So in other words, improve the immune system too much and it could arguably make the symptoms of an infection worse.

Optimising your immune system

However what you can do, says GP Dr Rob Hicks, is to take steps to ensure your immune system is working at its best.

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

So how can you do this?

Take some exercise

Studies suggest it doesn’t just make you feel fitter; it can help keep you free of bugs too. When scientists tracked the habits of 100 adults for three months they 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 in 2010 (the exercisers had five days with a cold over three months – whereas the non-exercisers had nine days.

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

So how much should you do?  ‘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,’ says Professor Mike Gleeson professor of exercise biochemistry  at Loughborough University.  However, if you do a lot of exercise – more than an hour and a half - in a single session then this has a stressful effect on the body and depresses immune function for up to 24 hours.


• 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,’ says Professor Calder

• Zinc: ‘There is also some similar evidence for zinc being beneficial for the immune system.

‘However, some people then think that they need to take as much zinc or vitamin C as they can but that’s not the case.

‘Take too much zinc for example and you become deficient in copper as excess zinc reduces the body’s ability to absorb copper.’

• Probiotics: Professor Calder believes the most extensive work has been done into probiotics – a form of beneficial bacteria found in the gut – where astonishingly 70 per cent of the immune system is located.

‘There are studies including some looking at the elderly and how well they respond to vaccinations and it seems that probiotics can improve their immune response –  but the difference it makes is quite small,’ he says.

‘Elderly people are more susceptible to infections because they are more prone to nutritional deficiency or immune abnormalities.’

If you are a busy person leading an unhealthy lifestyle, then it may be worthwhile taking a multivitamin and probiotic to ensure your immune system is working at its optimum level suggests Professor Calder.

Get an early night

A study published in the European Journal of Physiology found that it is the early part of sleep that is especially important to 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 so that’s why an unusually late night may leave your more prone to a cold.


Eating a balanced diet, 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 and a healthy immune system.

‘If someone is malnourished for example then their immune system is not going to be working as well as it might and if they get even a simple infection they may get sicker as a result,’ says Professor Calder.

‘Giving them better nourishment will improve their immune system.’

What else can you do?

‘My own favourite piece of advice - as well as the normal healthy lifestyle advice – is for people to keep laughing,’ says Dr Rob Hicks.

‘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 these people – the ones with a positive outlook who keep smiling seem to get ill less frequently.’

Page last reviewed on 13/07/2018