Many smokers may face lung damage in their later years even after quitting.
However an apple a day, and preferably two tomatoes, appear to slow the decline in lung function, which leads to irreversible lung disease. These foods could push back emphysema or chronic bronchitis by years, suggests research by Imperial College and the Johns Hopkins School of Public Health in the US.
The results show a diet high in tomatoes can slow the rate of lung damage by 4% in a decade because of the nutrients they contain. Lead author Dr Vanessa Garcia-Larsen, from Johns Hopkins, said: "This study suggests that a diet rich in fruits can slow down the lung’s natural ageing process even if you have never smoked."
Tobacco smoke contains more than 4000 chemicals that can damage the lungs’ natural defence system. These toxins create mucus, which blocks the lungs and weakens them as lung cells forced to clear the toxins are less able to control breathing efficiently. Tomatoes are thought to help because they are rich in vitamins such as lycopene, which combat the effects of the toxins.
Researchers measured the lung function of 680 smokers, ex-smokers and non-smokers. Among former smokers, those who ate a lot of fruit produced the highest readings when asked to blow into a measuring device.
Dr Garcia-Larsen said: "Our study suggests that eating more fruits on a regular basis can help reduce the decline as people age, and might even help repair damage caused by smoking."
Once lung function falls below 70%, someone is classed as having chronic obstructive pulmonary disease, which is a form of irreversible lung damage.
The study, published in the European Respiratory Journal, suggests diet could help delay this diagnosis in former smokers. Tomatoes, apples, bananas, herbal tea and vitamin C were all significantly linked with an improvement in lung function.