Consuming more fruit and veg might stave off lung disease.
The health benefits of eating a range of fruits and vegetables are well documented; reams of research has already made this clear.
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.
Although the study was conducted on a large scale, it still needs replication. An editorial, released in the same publication, written by Dr. Raphaelle Varraso and Dr. Seif Shaheen, argues that because this study is observational, no firm conclusions can be drawn regarding cause and effect; however, they write:
"[I]t could be argued that there is nothing to be lost by acting now. 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."
So, although more research will be needed before conclusions can be definitively drawn, quitting smoking and eating more fruits and vegetables is still the best course of action for overall health.