Sorry Camilla, ex-smokers are more susceptible to infections. But from singing to eating spinach, there ARE ways you can keep trouble at bay

The Queen was forced to withdraw from attending the Royal Variety Performance last week – one of several appointments she has now missed due to a respiratory infection.

At a recent event at Buckingham Palace, the Queen revealed to actress Emily Mortimer that she had quit smoking 20 years ago.

This begs the question: Can a history of smoking make those who kick the habit more susceptible to respiratory infections – and if so, what can they do to protect themselves?

Ex-smokers are more susceptible to everything from colds and flu to pneumonia, experts say. They are also more likely to have worse symptoms. ‘Even if your lungs are slightly damaged by smoking, you are more susceptible to infections,’ says Professor Nick Hopkinson, a respiratory physician at the Royal Brompton Hospital in London and medical director of the charity Asthma + Lung UK.

In healthy lungs, sticky mucus (sputum) traps harmful particles and bacteria, carrying them to the throat where they are swallowed and destroyed. Immune cells simultaneously patrol the lungs and destroy any insects. But in smokers, the lungs become inflamed and produce too much mucus. When this gets stuck, smokers cough it up.

It also causes direct damage to lung cells, making it harder for the lungs to inflate and deflate, leading to shortness of breath.

Camilla smokes while riding the Beaufort Hunt in 1996

‘Once you start to experience symptoms caused by smoking – including phlegm, coughing and shortness of breath – then it is more likely that there is already some lung damage,’ adds Professor Hopkinson.

Smoking also changes the microbiome (the community of bacteria and viruses) in the lungs.

This makes it easier for harmful insects (particularly streptococci – a major cause of respiratory infections, especially pneumonia) to cause further damage, explains William Cookson, professor of genomic medicine at Imperial College London’s National Heart and Lung Institute.

If you continue to smoke, the inflammation causes progressive scarring of the airways. Smoking for a decade or more is likely to cause permanent damage – appearing to make people more susceptible to respiratory infections and increasing the risk of diseases such as lung cancer, says Professor Cookson.

When you stop smoking, inflammation in the lungs decreases, the immune system works better, the microbiome returns to normal and, although the scarring remains, it does not get worse.

‘However, the scarring can leave you vulnerable to chronic infections with insect pests, including Haemophilus influenzae and Streptococcus pneumoniae, which cause new damage and episodes of pneumonia – but ex-smokers do not suffer nearly as badly as persistent smokers,’ says Professor Cookson.

There are ways current and former smokers can help keep breast problems at bay. ‘Staying active is really important – exercise helps improve lung capacity,’ explains Dr John Conibear, clinical director of pulmonary oncology at Barts Health NHS Trust in London. “Even starting to sing will improve it.”

Eating a healthy diet rich in antioxidants (berries, spinach and nuts) and omega-3 fatty acids (oily fish and flaxseed) can improve lung health, adds Dr. Conibear, who also practices at Harley Street Clinic in London works. Try to avoid lung irritants, such as fumes from chemicals found in cleaning products, as these can cause further damage.

And keep in mind that it’s never too late to stop. Smoking ‘increases the risk of cancer, stroke, heart attack, cataracts, macular degeneration, erectile dysfunction and osteoporosis’, says Professor Hopkinson.

‘The benefits of giving up can have a big impact, even if you quit at an older age. It’s the difference between being able to walk to the car or not being able to play with your grandchildren.”