Researchers studying patients who were admitted to the Canisius Wilhelmina hospital in the Dutch city of Nijmegen have found a link between vitamin K deficiency and the most serious coronavirus outcomes. Patients who have been treated in intensive care units or who have died from the infection have been found to be deficient in vitamin K.

The research was conducted in partnership with the Cardiovascular Research Institute Maastricht, one of Europe’s largest heart and vascular research institutes. However, there has been no formal clinical trial involving vitamin K and coronavirus and therefore no peer review.

Dr Rob Janssen, who has been working on the project, said that he encourages a healthy intake of vitamin K, except for patients receiving blood-thinning medications such as warfarin.

He said: “We are in a terrible, horrible situation in the world. We do have an intervention which does not have any side effects, even less than a placebo. There is one major exception: people on anti-clotting medication. It is completely safe in other people. My advice would be to take those vitamin K supplements. Even if it does not help against severe Covid-19, it is good for your blood vessels, bones and probably also for the lungs.”

Dr Janssen added: “We have [vitamin] K1 and K2. K1 is in spinach, broccoli, green vegetables, blueberries, all types of fruit and vegetables. K2 is better absorbed by the body. It is in Dutch cheese, I have to say, and French cheese as well.”