Regular consumption of leafy green vegetables may be associated with a lower risk of developing chronic obstructive pulmonary disease (COPD). Researchers at Edith Cowan University have observed this link in individuals who consume higher amounts of vitamin K1, which is abundant in spinach, kale, and broccoli.
The study analyzed data from over 179,000 participants in the UK Biobank project. The team evaluated dietary intake of vitamins K1 and K2, with follow-up averaging 10.5 years. During this time, COPD was diagnosed in 3,135 participants, and asthma was identified in an additional 4,269.
Participants with the highest intake of vitamin K1 had a 16% lower risk of developing COPD compared to those with the lowest intake. Spirometry tests also revealed higher forced vital capacity and forced expiratory volume in this group. No similar relationship was found with vitamin K2, which is mainly present in meat, eggs, and dairy products.
Vitamin K is primarily recognized for its role in blood clotting, but it also activates a protein called MGP. This protein helps protect elastin, the fibers responsible for the lungs’ ability to expand and contract during breathing. In COPD, these elastic fibers gradually degrade, making respiration more difficult.
The authors acknowledge that the observed association may not be solely due to vitamin K1. Leafy greens are also rich in dietary fiber and antioxidants, which may have beneficial effects on the body. Furthermore, foods high in K1 are typically part of a healthier overall diet, while sources of K2 are linked to different eating patterns.
The strongest link between high vitamin K1 intake and better lung function was found in smokers and individuals exposed to polluted air—specifically, those regularly encountering dust, smoke, and chemical fumes. However, the study was observational and does not prove that leafy greens directly prevent COPD.
The researchers also note that people who consume more vegetables may be more likely to exercise, smoke less, and eat fewer ultra-processed foods. Nevertheless, these findings add to the evidence suggesting a possible role for diet in maintaining lung health. According to the researchers’ estimates, the level of vitamin K1 associated with better lung function could be achieved by adding just one extra serving of leafy greens to the daily diet.
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