Dietary vitamin K intakes, chronic obstructive pulmonary disease, adult asthma, and lung function: a prospective cohort study in the UK Biobank

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. This study aimed to investigate the associations between dietary intakes of vitamin K 1 and K 2 and the incidence of chronic obstructive pulmonary disease (COPD), asthma, and lung function. We analysed data from 179,062 UK Biobank participants without COPD or asthma. Associations between dietary vitamin K 1 and K 2 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 (FEV 1 ), forced vital capacity (FVC), and the FEV 1 /FVC ratio were assessed using splines within multiple regression. Stratified analyses were performed by sex, smoking status, and occupation. Over 10.5-years follow-up, higher vitamin K 1 intakes were associated with lower COPD rates, with inverse associations plateauing above ∼250 μg/day [HR Q5versusQ1 : 0.84 (95% CI: 0.75, 0.94)], whereas no association was observed for vitamin K 2 . No associations were observed between vitamin K 1 or K 2 intakes and asthma. Higher vitamin K 1 intakes (Q5 versus Q1) were associated with better lung function [FVC: 44 mL (95% CI: 35, 53) and FEV 1 : 32 mL (95% CI: 25, 40)], while vitamin K 2 showed weaker and non-linear associations. Stronger associations between vitamin K 1 and lung function were evident in smokers and participants with high-risk occupations. Higher dietary vitamin K 1 intake was associated with better lung function and a lower rate of COPD. As vitamin K 1 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.