Plant-based diet may halve emphysema risk for young smokers

Diet cited in new US study as one way to lower risk of this COPD type

Margarida Maia, PhD avatar

by Margarida Maia, PhD |

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Young adults who smoke or have smoked may halve their risk of developing emphysema — a form of chronic obstructive pulmonary disease (COPD) — by eating a nutritionally rich, plant-based diet, a new U.S. study suggests.

The study, “A Plant-Centered Diet is Inversely Associated With Radiographic Emphysema: Findings from the CARDIA Lung Study,” was published in Chronic Obstructive Pulmonary Diseases: Journal of the COPD Foundation.

“Identifying these modifiable factors, such as diet, is vital for helping reduce the risk of developing chronic lung disease in those with a history of smoking,” Mariah K. Jackson, PhD, a nutritionist and the first author of the study, said in a COPD foundation press release.

“We know long-term smoking cessation adherence can be challenging, requiring complementary treatments, like a nutrient-rich plant-centered diet, to help preserve lung health,” added Jackson, an assistant professor at the University of Nebraska Medical Center.

In emphysema, a progressive form of COPD, damage to the air sacs in the lungs causes breathing difficulties that tend to get worse over time.

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How much and how long someone has been smoking influence how fast emphysema symptoms develop or worsen, research has shown. But despite the known link between smoking and COPD, data suggest that, at most, one-quarter of people who stop smoking quit for good.

“While smoking remains the primary environmental risk factor for the development of emphysema, smoking cessation interventions have resulted in long-term quit success rates in only up to 25% of patients,” the researchers wrote.

As such, they noted that “a simultaneous focus on other treatable traits is greatly needed to mitigate the adverse health effects of tobacco use across the life course.”

Data from a long-term observational study, called Coronary Artery Risk Development in Young Adults, or CARDIA, showed that young adults eating a plant-based diet that’s rich in fruits, vegetables, and whole grains — and sparse in refined grains and red and processed meats — were less likely to develop cardiovascular disease and to die from it.

CARDIA involved more than 5,000 Black and white adults, ages 18 to 30, from four geographically diverse U.S. cities. The participants were followed for three decades.

Additional analyses on CARDIA data suggested that long-term adherence to a nutritionally-rich plant-centered diet may help to maintain healthier lungs.

“Emerging data show an association between an individual’s dietary choices and lung health, including reducing wheezing in children and lowering asthma occurrence in children and adults,” Jackson said.

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It’s not known, however, if this type of diet can reduce the risk of developing emphysema. To know more, Jackson and other researchers followed 1,351 young adults who took part in the CARDIA study and who reported smoking at any time point prior to year 20 of follow-up.

The participants’ eating habits were assessed over time using a new tool called the A Priori Diet Quality Scores, or APDQS. This tool favors nutritionally rich plant foods over less nutritious ones while also considering the quality of animal foods. Scores range from 0 to 132, and higher scores indicate greater adherence to a high-quality diet.

“Plant-based foods such as fruits, avocado, green and yellow vegetables, and whole grains contribute to a higher score, while higher intakes of plant-based foods like fried potatoes, grain desserts, margarine, and fruit juice would result in lower scores,” the researchers wrote.

APDQS averaged 64.6 points at CARDIA’s start and remained consistent over time. People with a higher APDQS were significantly more likely to be older, female, and white individuals than those with a lower APDQS. A higher score also was linked to more educated and more physically active individuals, who were more likely to eat a less-caloric diet, smoke less, and have better lung function.

A total of 175 people (13%) showed signs of emphysema on computed tomography (CT) scans taken at year 25 of follow-up, according to the researchers. The proportion of people who developed emphysema was about five times smaller among those in the highest APDQS group versus those in the lowest APDQS group (4.5% vs. 25.4%).

After adjusting analyses for potential influencing factors such as age, sex, and race, the team found that people who strongly followed a nutritionally-rich, plant-based diet — those in the highest APDQS group — had a 56% lower risk of developing emphysema compared with those with the lowest adherence to the diet.

Even after accounting for the impact of smoking, eating a nutritionally rich, plant-centered diet throughout young and middle adulthood was related to a decreased risk of emphysema developing later in life.

Importantly, according to the scientists, this association between diet and emphysema risk was independent of smoking history.

“Emphysema was the least common in those with the best diet,” the researchers wrote. “Even after accounting for the impact of smoking, eating a nutritionally rich, plant-centered diet throughout young and middle adulthood was related to a decreased risk of emphysema developing later in life.”

Jackson noted that promoting such a diet could offer an additional strategy to possibly lower a person’s risk of developing emphysema. But “more research is needed on when dietary choices have the most potential to impact lung health, which can then inform public health guidelines and dietary recommendations, especially in children and young adults,” Jackson said.