Eating Fruits and Vegetables Reduces Lung Disease Risk

Research, published this week in Thorax, finds a link between eating greater quantities of fruits and vegetables and lung health. They found it lowered the risk of developing a chronic obstructive pulmonary disease in former and current smokers.
[Lungs colored X-ray]
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.

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 fewer 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.

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.


Eating 10 Portions of Fruits and Vegetables Daily Best for Health

Eating five portions of fruits and vegetables daily is considered sufficient for good health. But according to a new study, the greatest benefits come from eating 10 portions a day.
[A colorful selection of fruits and vegetables]
Researchers say eating 10 portions of fruits and vegetables daily is best for preventing disease and premature death.

From an analysis of 95 studies assessing the health benefits of fruit and vegetable consumption, researchers found that eating 800 grams of fruits and vegetables daily – or around 10 portions of 80 grams – was associated with the lowest risk of disease and premature death.

Apples, pears, green leafy vegetables, and cruciferous vegetables were found to be among the most beneficial for health.

Lead author Dr. Dagfinn Aune, of the School of Public Health at Imperial College London in the United Kingdom, and colleagues recently reported their findings in the International Journal of Epidemiology.

Current guidelines recommend that adults should aim to eat around five cups of fruits and vegetables daily – two cups of fruits and three cups of vegetables – to help reduce the risk of heart disease, stroke, cancer, and other chronic diseases.

While consuming five portions of fruits and vegetables daily is beneficial, Dr. Aune and colleagues set out to determine how many fruits and vegetables need to be consumed for maximum protection against disease and early death.

To reach their findings, the researchers analyzed the data of 95 studies that looked at the health benefits of fruit and vegetable intake.

In total, the studies involved almost 2 million participants and around 43,000 cases of heart disease, 47,000 cases of stroke, 81,000 cases of cardiovascular disease (CVD), and 94,000 deaths.

The team analyzed the fruit and vegetable intake of each participant, looking specifically at how much they consumed daily and the specific fruits and vegetables consumed.

Up to 33 percent lower risk of disease and death with 10 portions daily

One portion of fruits of vegetables was defined as 80 grams – the equivalent of a small banana, pear, or apple, or three heaped tablespoons of cooked vegetables, such as peas, broccoli, or cauliflower.

The researchers then calculated the association between fruit and vegetable intake and the risks of heart disease, stroke, CVD, cancer, and premature death.

The team found that, compared with no fruit and vegetable consumption, participants who ate just 200 grams of fruits and vegetables a day – the equivalent to around 2.5 portions – saw health benefits. These included an 18 percent reduced risk of stroke, a 16 percent reduced risk of heart disease, a 13 percent lower risk of CVD, and a 4 percent reduced risk of cancer.

Eating 200 grams of fruits and vegetables daily was also associated with a 15 percent lower risk of premature death.

However, the researchers found that the more fruits and vegetable participants ate daily, the greater the benefits.

Compared with subjects who consumed no fruits and vegetables, those who ate up to 800 grams – or 10 portions – each day were found to have a 33 percent lower risk of stroke, a 28 percent reduced risk of CVD, a 24 percent lower risk of heart disease, and a 13 percent decrease in cancer risk.

A 31 percent reduction in premature death was also associated with a daily fruit and vegetable intake of up to 800 grams.

What is more, the researchers calculated that if everyone ate 10 portions of fruits and vegetables daily, then around 7.8 million premature deaths could be prevented across the globe annually.

Which fruits and vegetables are best?

The team found that apples, pears, citrus fruits, green leafy vegetables (such as chicory and spinach), and cruciferous vegetables (such as cabbage and broccoli) were best for reducing the risk of stroke, CVD, heart disease, and premature death.

The greatest reduction in cancer risk was associated with intake of green vegetables (such as green beans), yellow vegetables (such as peppers and carrots), and cruciferous vegetables.

Consumption of raw and cooked vegetables was associated with reduced risk of premature death, but the team did not have enough data to determine which specific fruits and vegetables reduced this risk.

While the study did not investigate the mechanisms behind high fruit and vegetable intake and reduced risk of disease and death, the team notes that fruits and vegetables have been linked to lower cholesterol and improved blood vessel and immune system function.

“This may be due to the complex network of nutrients they hold,” notes Dr. Aune. “For instance, they contain many antioxidants, which may reduce DNA damage, and lead to a reduction in cancer risk.”

Overall, the researchers believe their findings highlight the importance of fruits and vegetables as part of a healthful diet.

“We need further research into the effects of specific types of fruits and vegetables and preparation methods of fruit and vegetables. We also need more research on the relationship between fruit and vegetable intake with causes of death other than cancer and cardiovascular disease.

However, it is clear from this work that a high intake of fruit and vegetables hold tremendous health benefits, and we should try to increase their intake in our diet.”

Dr. Dagfinn Aune