Abstract
BACKGROUND: Vitamin K-dependent proteins are important for maintaining lung structure and function, yet few studies have examined dietary vitamin K intake in relation to chronic respiratory disease.</p>
OBJECTIVES: This study aimed to investigate the associations between dietary intakes of vitamin K1 and K2 and the incidence of chronic obstructive pulmonary disease (COPD), asthma, and lung function.</p>
METHODS: We analysed data from 179,062 UK Biobank participants without COPD or asthma. Associations between dietary vitamin K1 and K2 intakes, estimated using the Oxford WebQ 24-hour recall, and incident COPD and asthma, identified through hospital, death and primary care records, were examined using Cox proportional hazards models. In cross-sectional analyses, associations of vitamin K intake with forced expiratory volume in one second (FEV1), forced vital capacity (FVC), and the FEV1/FVC ratio were assessed using splines within multiple regression. Stratified analyses were performed by sex, smoking status, and occupation.</p>
RESULTS: Over 10.5-years follow-up, higher vitamin K1 intakes were associated with lower COPD rates, with inverse associations plateauing above ∼250 μg/day [HRQ5versusQ1: 0.84 (95% CI: 0.75, 0.94)], whereas no association was observed for vitamin K2. No associations were observed between vitamin K1 or K2 intakes and asthma. Higher vitamin K1 intakes (Q5 versus Q1) were associated with better lung function [FVC: 44 mL (95% CI: 35, 53) and FEV1: 32 mL (95% CI: 25, 40)], while vitamin K2 showed weaker and non-linear associations. Stronger associations between vitamin K1 and lung function were evident in smokers and participants with high-risk occupations.</p>
CONCLUSION: Higher dietary vitamin K1 intake was associated with better lung function and a lower rate of COPD. As vitamin K1 is abundant in green leafy vegetables (e.g., ∼1 serving of kale, ∼1½-2 cups), higher consumption of these foods within a healthy diet may be associated with favourable respiratory health.</p>