Signs that your immune system might be low, and what you can do about it

As the days get cooler and darker, you might find your immune system tanking. Here’s how to nip those snivels and coughs in the bud before they develop.

The mornings are getting darker, the days becoming colder and we’re on the cusp of bringing back out coats and boots again. As we adjust to the chillier weather, it’s probably time we start preparing ourselves for our winter colds, too.

It’s a fact that we’re naturally more susceptible to colds during the cooler months, but there are ways to fight back. While “boosting your immune system” is an inaccurate phrase, looking after your immunity is still important. According to Dr Sarah Brewer, a GP and the medical director of vitamin and supplement brand Healthspan, a strong immune system is the key to staying healthy no matter what the elements throw our way. The immune system “protects against disease by recognising and attacking infections,” she explains.

It functions in two ways: ‘innate’ immunity (protections that are programmed into all of us as general defences against disease) and ‘acquired’ immunity (specific measures in the body aimed against a particular infection once we have encountered it for long-term immunity – how vaccines work).

What are the signs of a low immune system?

A ‘low’ immune system simply means that you are more likely to experience symptoms when exposed to a common cold virus or bacteria. So, the most common sign that your immunity is low is that you have frequent or prolonged colds (pre-Covid, the average was around one cold a year, lasting seven to 10 days).

Immune system: the most common sign that your immunity is low is that you have frequent or prolonged colds.

Why is my immune system low?

There are many reasons why someone might have lower than usual immunity. Dr Brewer says that “one theory is, as people get older, they develop more vitamin and mineral deficiencies that contribute to reduced immunity with higher levels of inflammation”. She points to a recent study from Oregon State University which found that people aged 55 and over who took a daily multivitamin and mineral supplement for 12 weeks were able to fight off infections twice as fast as those taking a placebo.

But it’s about more than just nutrition. Have you ever noticed that you get wiped out with a cold just before a job interview or big event? That’s because stress has a huge impact on our immunity, says Dr Brewer: “Numerous studies have demonstrated that long term stress has the ability to reduce the functionality of key components of the immune system which can, in turn, leave you open to infection.”

How can I support my immune system?

Getting in the right nutrients is essential for optimum functioning of the body – including the immune system. Vitamin D and vitamin C are what to focus on: research by the World Health Organisation has shown that taking vitamin D supplements can reduce your risk of experiencing at least one respiratory infection, including the common cold, influenza or pneumonia, by a third. Other studies show that vitamin C suppresses the activation of viral genes so that cold viruses cannot survive in cells.

While the NHS recommends taking a vitamin D supplement, especially during the winter months, we should also try to focus on “eating a Mediterranean style diet with plenty of fruit and vegetables, onions, garlic, oily fish and wholegrains” to ensure that we are giving our immune systems the nutrients it needs to function, says Dr Brewer.

Other lifestyle tweaks you can make to support your immunity include exercise, which can neutralise the harmful effects of stress hormones. “Exercise should be non-competitive, so avoid over-training and marathons [to support immunity] as physical stress suppresses immunity and increases the risk of developing symptoms when exposed to a common cold virus,” Dr Brewer advises.

And get some sleep! “During sleep, your body secretes hormones involved in fighting disease. People who sleep for seven to eight hours have better immunity than those who are sleep deprived, and tend to live longer, too.”