The health benefits of eating a range of fruits and vegetables are well documented; reams of research has already made this clear.

For instance, increasing their consumption helps reduce cardiovascular risk, maintain a healthy blood pressure, and stave off cancer, to name but a few.

Recently, there have been a number of studies demonstrating that consuming fruit and veg might also protect lung health.

Chronic obstructive pulmonary disease (COPD) is a range of conditions characterized by a narrowing of the airways, including emphysema and bronchitis. Worldwide, COPD currently affects more than 64 million people.

The major risk factor for COPD is smoking, and the World Health Organization (WHO) predict that, by 2030, it will become the third leading cause of death on a global basis.
 

COPD and dietary factors

Some earlier studies have found that dietary factors might play a role in COPD. To delve into this question in more detail, a group of researchers tracked the respiratory health of more than 44,000 Swedish men. Aged 45-79 at the start of the trial, the participants were followed for an average of 13.2 years, up to the end of 2012.

Each participant completed a food frequency questionnaire that collated how often they ate 96 different food items in 1997, the first year of the study. Other factors were also collected, including height, weight, education level, physical activity, and alcohol consumption.

The participants were asked how many cigarettes they smoked, on average, at ages 15-21, 21-30, 31-40, 41-50, and 51-60. Overall, 63 percent had smoked at one point in their life, 24 percent were current smokers, and 38.5 percent had never smoked.

Occurrences of COPD were registered across the time period; there were 1,918 in total. The rate of COPD in those who ate fewer than two portions of fruits and vegetables per day was 1,166 per 100,000 people in current smokers and 506 per 100,000 in former smokers.

However, for those eating five portions per day, the equivalent numbers were 546 and 255, respectively. This means that individuals eating five daily servings of fruits and vegetables had a 35 percent reduced risk of developing COPD compared with those eating two or less portions. When the reduction in risk was split into current and former smokers, the percentages were 40 percent and 34 percent, respectively.

Each extra serving of fruits and vegetables was associated with a 4 percent lower risk of COPD in former smokers and an 8 percent lower risk in current smokers.

Compared with individuals who had never smoked and who ate five or more portions of fruits and vegetables, current and former smokers who ate fewer than two daily portions were 13.5 times and six times more likely to develop COPD, respectively.

The authors conclude:

    "The present findings confirm the strong impact of cigarette smoking on the development of COPD and also indicate that diet rich in fruit and vegetables may have an important role in prevention of COPD.

    Nevertheless, nonsmoking and smoking cessation remain the main public health message to prevent development of COPD."

Which fruits and vegetables reduced COPD risk?

As part of the analysis, the researchers assessed which particular foodstuffs were most effective at reducing the COPD risk. They found that green leafy vegetables, peppers, apples, and pears had the strongest influence on reducing risk.

However, berries, citrus fruits, bananas, root and cruciferous vegetables, tomatoes, garlic, onions, and green peas did not exert a significant effect.

Because smoking increases oxidative stress and inflammation, both of which are potentially involved in COPD, the antioxidants present in fruits and vegetables might help reduce their negative impact.