Eating lots of fruit and vegetables can cut the risk of smoking-related diseases, finds new research.
According to a report by BBC Online, scientists have long tried to explain why some heavy smokers fall ill as a result of their habit, but others stay in reasonably good health.
They believe that a combination of factors, including genes, diet and other lifestyle factors are key, but evidence to support the diet link was published this week in the European Respiratory Journal.
A study of 300 smokers over the age of 45 who had smoked the equivalent of a pack of 20 cigarettes a day for a decade, found that diet was a significant factor.
The risk of developing chronic obstructive pulmonary disease (COPD) - a progressive and incurable combination of bronchitis and emphysema - dropped by more than half when smokers ate more than 121 grams of fruit and vegetables daily.
The study suggested that it was the combination of fruit and vegetables, rather than the sheer quantity of each, that was important in disease prevention.
Study leader, Dr Louise Watson from the University of Southampton, told BBC Online: "No other food groups such as fish and dairy, or proteins, fats and snack items were significantly protective or harmful, which suggests the effect is specific to fruit and vegetables and not due to the effect of COPD on overall calorie or food intake."
The findings add to the already substantial evidence supporting the role of fruit and vegetables in the diet.
It is thought that antioxidants found in the foods may help "mop up" harmful free radicals circulating in the body, and cigarette smoke contains a large amount of free radicals, which damage cells and cause malignant changes.
However, Dr Watson stressed that while eating well might reduce the chances of falling ill, there was still an increased risk compared to someone who gave up smoking entirely.
She recommended that giving up smoking entirely is still the best way of avoiding COPD.