Associations of a plant-centered diet and lung function across early to mid-adulthood: The CARDIA Lung Study

Background: Lung function throughout adulthood predicts morbidity and mortality even among adults without chronic respiratory disease. Diet quality may represent a modifiable risk factor for lung function impairment later in life. We investigated associations between nutritionally-rich plant-centered diet and lung function across early and middle adulthood from the Coronary Artery Risk Development in Young Adults (CARDIA) Study. Methods: Diet was assessed at baseline and years 7 and 20 of follow-up using the validated CARDIA diet history questionnaire. Plant-centered diet quality was scored using the validated A Priori Diet Quality Score (APDQS), which weights food groups to measure adherence to a nutritionally-rich plant-centered diet for 20 beneficially rated foods and 13 adversely rated foods. Scores were cumulatively averaged over follow-up and categorized into quintiles. The primary outcome was lung function decline, including forced expiratory volume in 1 s (FEV₁) and forced vital capacity (FVC), measured at years 0, 2, 5, 10, 20, and 30. We estimated the association of APDQS with annual pulmonary function changes and cross-sectional differences in a repeated measures regression model, adjusting for clinically relevant covariates. Results: The study included 3,787 Black and White men and women aged 18–30 in 1985–86 and followed for 30 years. In multivariable repeated measures regression models, individuals in the lowest APDQS quintile (poorest diet) had declines in FEV₁ that were 1.6 ml/year greater than individuals in the highest quintile (35.0 vs. 33.4 ml/year, ß ± SE per 1 SD change APDQS 0.94 ± 0.36, p = 0.009). Additionally, declines in FVC were 2.4 ml/year greater in the lowest APDQS quintile than those in the highest quintile (37.0 vs 34.6 ml/year, ß ± SE per 1 SD change APDQS 1.71 ± 0.46, p < 0.001). The association was not different between never and ever smokers (p_int = 0.07 for FVC and 0.32 for FEV₁). In sensitivity analyses where current asthma diagnosis and cardiorespiratory fitness were further adjusted, results remained similar. Cross-sectional analysis at each exam year also showed significant differences in lung function according to diet after covariate adjustment. Conclusions: In this 30-year longitudinal cohort study, long-term adherence to a nutritionally-rich plant-centered diet was associated with cross-sectional differences in lung function as well as slower decline in lung function, highlighting diet quality as a potential treatable trait supporting long-term lung health.