The study from Johns Hopkins Bloomberg School of Public Health in the US found that the natural decline in lung function over a 10-year period was slower among former smokers with a diet high in tomatoes and fruits.
The researchers found that adults who on average ate more than two tomatoes or more than three portions of fresh fruit a day had a slower decline in lung function compared to those who ate less than one tomato or less than one portion of fruit a day, respectively.
The researchers inquired about other dietary sources such as dishes and processed foods containing fruits and vegetables (eg tomato sauce) but the protective effect was only observed in fresh fruit and vegetables.
The study, led by Imperial College London in the UK, also found a slower decline in lung function among all adults, including those who had never or had stopped smoking, with the highest tomato consumption.
Poor lung function has been linked with mortality risks from all diseases, including chronic obstructive pulmonary disease (COPD), heart disease, and lung cancer.
“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 lungs natural ageing process even if you have never smoked,” said Vanessa Garcia- Larsen, assistant professor at Johns Hopkins.
“The findings support the need for dietary recommendations, especially for people at risk of developing respiratory diseases such as COPD,” said Garcia-Larsen, lead author at European Respiratory Journal.
For the study, researchers assessed diet and lung function of more than 650 adults in 2002, and then repeated lung function tests on the same group of participants 10 years later.
Participants from three European countries – Germany, Norway and the UK – completed questionnaires assessing their diets and overall nutritional intake.
They also underwent spirometry, a procedure that measures the capacity of lungs to take in oxygen.
The test collects two standard measurements of lung function: Forced Exhaled Volume in 1 second (FEV1), which measures how much air a person can expel from their lungs in one second; and Forced Vital Capacity (FVC), the total amount of air a person can inhale in six seconds.
The study controlled for factors such as age, height, sex, body mass index, socio-economic status, physical activity and total energy intake.
Among former smokers, the diet-lung-function connection was even more striking.
Ex-smokers who ate a diet high in tomatoes and fruits had around 80 ml slower decline over the ten-year period.
This suggests that nutrients in their diets are helping to repair damage done by smoking.
“Lung function starts to decline at around age 30 at variable speed depending on the general and specific health of individuals,” said Garcia-Larsen.
“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 COPD around the world,” she said.