A plant-centric diet in early adulthood was associated with less risk of emphysema in middle age, results of a long-running cohort study indicated.
Participants whose diets at enrollment were in the top quintile on the A Priori Diet Quality Score (APDQS) system had 60% lower odds of developing emphysema over 30 years of follow-up versus those with diets in the bottom quintile (adjusted OR 0.40, 95% CI 0.18-0.91), reported Ann Wang, MD, of the Icahn School of Medicine at Mount Sinai in New York City.
Examined another way, each standard deviation higher in APDQS score was associated with a 34% reduction in odds of emphysema in middle age (P=0.008), Wang said at the American Thoracic Society’s (ATS) annual meeting here. The study is just the latest to emerge from the famous CARDIA project, which began in 1985 to examine the risks of coronary artery disease in young adults.
CARDIA leaders estimate that more than 900 papers based on the study have been published or are in press, many on topics far removed from coronary artery disease. Participants contributed a wealth of data on behavioral and lifestyle factors when joining the project and their subsequent health history was tracked regularly.
Follow-up included periodic spirometry tests, a review of dietary habits, and lung CT imaging at year 25 to establish the presence of emphysema. About two-thirds of the original 5,115 participants were retained through 30 years of follow-up.
Wang and colleagues saw the dataset as potentially revealing for respiratory disease risks and progression in younger people, particularly those taking up smoking in adolescence. In her ATS talk, Wang explained that young adulthood is a “critical period” in which individuals’ subsequent health trajectory is determined to a large degree. Smoking is by far the biggest risk factor for respiratory disease, but it’s not the only one. Thus, she and her colleagues sought to look at the contribution of diet.
As its name suggests, APDQS scores are based on hypotheses supported by evidence but not proven — that meats and other animal products are relatively unhealthy whereas plant-based foods are healthy. The more fruits, vegetables, and leafy greens consumed, the higher the score. Those in the top quintile would qualify as essentially vegetarian, while those in the bottom quintile are those who rely largely on animal proteins and fats and don’t eat a lot of salad.
Statistical analyses concerning diet quality and emphysema at follow-up were adjusted for smoking history, body mass index, total dietary caloric value, and sociodemographic characteristics.
In addition to those analyses, Wang’s group also looked at APDQS scores about overall lung function over time in ever-smokers, measured by forced expiratory volume in 1 second and forced vital capacity at clinic visits. They found trends suggesting that higher diet quality ameliorated, but didn’t fully eliminate, declines in these parameters as participants aged.