People with low levels of Vitamin K in their blood are more likely to have poor lung function and to say they suffer from asthma, chronic obstructive pulmonary disease (COPD), and wheezing, according to a new study published on August 10.

Vitamin K is found in leafy green vegetables, vegetable oils, and cereal grains. It plays a role in blood clotting, and so helps the body to heal wounds, but researchers know very little about its role in lung health.

The new findings, published in the ERJ Open Research journal, do not alter the current advice on Vitamin K intake, but they do support further research to see if some people could benefit from taking its supplements.

"To our knowledge, this is the first study on Vitamin K and lung function in a large general population. Our results suggest that Vitamin K could play a part in keeping our lungs healthy," said researcher Dr Torkil Jespersen.

The study was done by a team of Danish researchers at Copenhagen University Hospital and the University of Copenhagen. It involved a group of 4,092 people aged between 24 and 77 years living in Copenhagen.

Study participants took part in lung function testing, called spirometry, gave blood samples and answered questionnaires on their health and lifestyle.

The blood tests included a marker of low levels of Vitamin K in the body. Spirometry measures the amount of air a person can breathe out in one second (forced expiratory volume or FEV1) and the total volume of air they can breathe in one forced breath (forced vital capacity or FVC).

The researchers found that people with markers of low levels of Vitamin K had lower FEV1 and lower FVC on average. People with lower levels of Vitamin K were also more likely to say they had COPD, asthma, or wheezing.

"On their own, our findings do not alter current recommendations for Vitamin K intake, but they do suggest that we need more research on whether some people, such as those with lung disease, could benefit from vitamin K supplementation," said Jespersen.