Smokers who quit smoking and live on a diet high in tomatoes and fruits, particularly apples, have better chances of restoring their lung functions impaired by smoking, a new study finds.

The study, published in the December issue of the European Respiratory Journal, said former smokers who eat more tomatoes and fresh fruits on a regular basis saw a slower natural decline in lung function over a 10-year period.

According to the study, conducted by the Johns Hopkins Bloomberg School of Public Health, adults who on average ate more than two tomatoes or more than three portions of fresh fruits and vegetables a day had a slower decline in lung function, compared to those who ate less than one tomato or less than one portion of fruits, respectively, on a daily basis.

Lung function starts to decline at around age 30 and poor lung function is linked to higher risks of death from all diseases, including chronic obstructive pulmonary disease (COPD), heart disease and lung cancer.

"A diet rich in fruits can slow down the lung's natural aging process even if you have never smoked," said Vanessa Garcia-Larsen, the study's lead author, who is also an assistant professor in the Bloomberg School's Department of International Health.

Garcia-Larsen and her team examined diet and lung function of more than 650 adults from Germany, Norway and Britain in 2002 and performed lung function tests on the same group of participants 10 years later.

The researchers found a more striking diet-lung-function among former smokers, who had around 80 ml slower decline over the 10-year period because their diets were highly rich in tomatoes and fruits.

Such a result suggests that the nutrients in their diets are beneficial to repairing the lung damage done by smoking.

"Eating more fruits on a regular basis can help attenuate the decline as people age, and might even help repair damage caused by smoking," Garcia-Larsen said.