Abstract
Objective
To investigate whether the association between diet and lung function (LF) differs according to asthma or COPD status in the Lifelines cohort study.
Methods
We included adults from Lifelines with valid dietary and spirometry data. Dietary quality was calculated at baseline using the Lifelines diet score (LLDS) (range 0–48, where higher scores indicate a healthier diet). LF was assessed
via
pre-bronchodilator spirometry (forced expiratory volume in 1 s (FEV
1
), forced vital capacity (FVC) and FEV
1
/FVC) at baseline and two follow-ups (∼10 years). Cross-sectional associations between diet and LF were examined using linear regression and longitudinal associations with linear mixed-effects models. Interactions between diet and asthma or COPD were included.
Results
Higher LLDS was associated with higher LF and slower decline. In cross-sectional analyses (n=83 460, 59% female, mean age 44±13 years), higher LLDS was associated with higher FEV
1
and FEV
1
/FVC levels in participants with asthma (FEV
1
β
interaction
(β
int
)=2.48 mL, 95% CI 0.68–4.27; FEV
1
/FVC β
int
=0.027%, 0.003–0.052) and COPD (FEV
1
β
int
=8.31 mL, 6.93–9.69; FEV
1
/FVC β
int
= 0.094%, 0.079–0.109) compared with those without asthma or COPD. In longitudinal analyses (n=37 752, 59% female, age 46±11 years) in COPD-patients higher LLDS was associated with slower FEV
1
decline (β
int
=0.18 mL·yr
−1
, 0.04–0.33), FVC (β
int
=0.23 mL·yr
−1
, 0.04–0.41) and FEV
1
/FVC (β
int
=0.002%·yr
−1
, 0.000–0.005) compared with those without COPD.
Conclusions
Higher diet quality was associated with better LF, particularly in those with asthma or COPD, and with slower decline in participants with COPD. These findings suggest that diet may be a modifiable factor in respiratory health.