Smokers and ex-smokers may significantly reduce their risk of developing chronic obstructive pulmonary disease (COPD) by eating more fruit and vegetables, according to new research.
The study, which only included men, found that each additional serving of fruit or vegetables reduced their risk by 4 to 8 percent. But the effects were only seen in those with a history of smoking — suggesting that antioxidants in this type of food could counteract the damaging oxidizing effects of smoking on the airways.
The study, “Fruit and vegetable consumption and risk of COPD: a prospective cohort study of men,” appeared in the journal Thorax.
To study the impact of diet on COPD risk, researchers at Sweden’s Karolinska Institutet studied more than 44,000 men, which they followed for up to 13 years. The men were between 45 and 79 years old, and 1,918 of them developed COPD during the study period.
To relate their dietary habits to disease, researchers designed questionnaires asking the men to detail how often they ate 96 different foods. They were also queried on smoking, alcohol consumption and physical activity habits. In addition, researchers gathered data about demographic and basic patient parameters, such as weight and height.
The analysis showed that of 100,000 people, 1,166 current smokers were likely to fall ill if they ate less than two servings of fruit and vegetables per day. Among ex-smokers, the rate was 506 out of 100,000 people.
But among those who ate more than five portions of fruit and vegetables a day, the risk was significantly less: only 546 current smokers and 255 ex-smokers of 100,000 people got sick.
This translated to a 40 percent and 34 percent lower risk of disease among current and ex-smokers who ate plenty of fruit and vegetables compared to those who ate few fruits and veggies. Each additional serving lowered the risk by 4 percent among former smokers, and by 8 percent among current smokers.
The largest difference in risk was seen between men who ate more than five portions of fruit and vegetables per day and had never smoked, and current smokers who ate less than two portions a day. Men in the latter group were 13.5 times more likely to develop COPD. Among current smokers, this risk was reduced to 7.5 times if they ate plenty of fruit and vegetables.
Taking a closer look at particular types of fruit and vegetables, the research team found that apples, pears, peppers and leafy green vegetables to be particularly helpful in lowering the risk of COPD.
While researchers suggested that antioxidants in the diet may cancel out the oxidative effect of smoking on the airways, scientists who were not involved in the research caution that the study should be interpreted carefully. Two scientists, one from France’s INSERM and the other from Britain’s Queen Mary University of London, stated in an editorial that only a clinical trial could really demonstrate that a certain diet lowers disease risk.
Nevertheless, citing Hippocrates (“Let food be thy medicine and medicine be thy food”), the two scholars agreed that no harm can come by promoting a healthy diet.
“We would argue that clinicians should consider the potential benefits of a healthy diet in promoting lung health, and advocate optimizing intake of fruits and vegetables, especially in smokers who are unable to stop smoking,” they wrote.