Scientists say the fruits, particularly apples, are crammed with wonder chemicals that provide a protective effect.
Having at least two tomatoes or three pieces of fruit as part of the recommended five-a-day provides the biggest benefit.
Experts found the natural decline in lung function over a 10-year period was slower among former smokers with a diet packed with nature’s goodness.
The protective effect was only observed in fresh fruit and vegetables and not processed foods like sauces.
There was also a slower decline in lung function among all adults, including those who had never or had stopped smoking, with the highest tomato consumption.
Professor Vanessa Garcia-Larsen, of the John Hopkins Bloomberg School of Public Health in Baltimore, US, said: “This study shows that diet might help repair lung damage in people who have stopped smoking.
“It also suggests that a diet rich in fruits can slow down the lung’s natural ageing process even if you have never smoked.”
Researchers, including those from Imperial College, London, assessed the diet and lung function of more than 650 adults in 2002. A decade later tests were repeated on the same group from the UK, Germany, and Norway.
Diet and overall nutritional intake was assessed from questionnaires while participants also underwent spirometry, a procedure that measures the capacity of lungs to take in oxygen.
The study controlled factors such as age, height, sex, body mass, physical activity and total energy intake. Results among former smokers suggested nutrients in tomatoes and fruits help repair damage to their lungs.
Prof Garcia-Larsen said: “Lung function starts to decline at around age 30 at variable speed depending on the general and specific health of individuals.
“Our study suggests that eating more fruits on a regular basis can help attenuate the decline as people age and might even help repair damage caused by smoking.
“Diet could become one way of combating rising diagnosis of chronic obstructive pulmonary disease [COPD], all of which are made worse by smoking, around the world.”
An estimated 1.2million Britons live with COPD making it the second most common lung disease in the UK after asthma, according to the British Heart Foundation.
COPD is a group of lung conditions that cause breathing difficulties including emphysema, damage to the air sacs in the lungs and chronic bronchitis, the long-term inflammation of the airways.
Previous research has suggested apples, which are a rich source of vitamin C and K, magnesium, potassium and fibre, can slash the risk of an early death by more than a third.
They contain health-boosting flavanoids, which are believed to reduce the risk of killer conditions like cancer.
The fruit is thought to be good for heart health with its potent mix of fibre and polyphenols linked to reductions in the level of so-called “bad” cholesterol.
Apples and green tomatoes also possess natural chemicals that help halt the march of time.
Ursolic acid is found in the fruit’s waxy outer layer while tomatidine comes from the skins and leaves of green tomatoes. Both are thought to stop muscle wastage.
The findings were published in the European Respiratory Journal.