Facts and myths about the immune system

Much about what we ‘know’ about the immune system and how we can avoid getting ill stems from old wives’ tales, outdated or misunderstood science, or simply false advertising. There are however a few myths that have at least a base in reality – learn which ones!

Want to learn more? Read our guide to diet, exercise and the immune system!

Vitamin C helps cure a cold – MYTH

Taking vitamin C supplements or eating food high in vitamin C (think citrus fruits) does support your immune system but once you've caught something, it can't do much for you.

Getting a flu shot temporarily lowers your immune system – MYTH

It's true that you may experience mild flu symptoms after getting a flu shot but it does not impair your immune system. The flu shot will teach your immune system what to look for in case you do get infected, either killing off the infection entirely or reducing the severity of symptoms.

Being cold gives you a cold - MYTH

It is true that when it's cold outside, you’re more likely to catch a cold or flu. But this has more to do with spending more time indoors where the air is drier and you’re closer to other people who may pass on viruses to you. Being cold itself can't make you sick but it will necessarily make you uncomfortable.

The immune system crashes during exercise – MYTH

We used to think that hard exercise can cause a temporary lapse in the immune response – a so-called open window. Studies in the 1980s showed that during exercise, there were more immune cells in the blood than usual, but afterwards there was a marked reduction of immune cells.

Recent research suggests that this was a misinterpretation and that the missing immune cells travel to organs that are more likely to be infected during exercise, like the lungs and respiratory tract.

Drinking alcohol kills off bacteria – MYTH

While cleaning your hands with an alcohol-based sanitiser when you're out and about can drastically reduce your chance of getting sick, alcohol inside your body plays a more sinister role.

Your grandpa may have suggested a glass of brandy to burn off the nasties but there is no evidence that this works. You're more likely to prolong an illness by drinking as alcohol is a diuretic and can cause dehydration.

Eating chicken soup helps cure a cold - FACT

There's nothing inherently magical about chicken soup but a healthy soup is one of the better meals you can eat when sick. Chicken soup has 5 things your body needs when you're ill: water for rehydration, protein, vitamins and minerals to support your overall nutrition, and a comforting feeling that will help you relax so you can recover better.

Starve a fever, feed a cold – MYTH

There's a very old saying that goes: you should starve a fever but feed a cold. What was suggested is you shouldn't eat if you have a fever, but you should eat if you have a cold. While many struggle to eat when they have a fever, a healthy meal will only do you good whether it's just a cold or you have a fever as well.

An apple a day keeps the doctor away – FACT

If your diet consists of junk food and a single apple every day, it alone is unlikely to keep the doctor away, although the apple will be better than nothing. But eating a diet rich in fruit and vegetables will help you get enough vitamins which will support your immune system and likely reduce your trips to the GP.