The objective of the SAFE K study is to demonstrate that in patients treated with the antagonists of vitamin K (VKA), a daily intake of vitamin K2 (75 micrograms/day) as naturally produced by the ferments used in fermented dairy products, does not upset the balance of anticoagulant treatment.Fifty-two patients will be chosen to receive either verum or placebo for four months after a 4-month run-in period.In addition, the study evaluates if regular consumption of vitamin K2 reduce the need of changing the dose of anticoagulation treatment and improve the markers of bone mineralisation.

Randomisation of the study subjects will be done by two randomisation lists depending on whether the dose of VKA is high or low. Randomisation will be balanced and stratified depending on the average dose of VKA before the inclusion in order that each arm would have the same number of patients receiving a dose lower than the used anticoagulant treatments.

The level of vitamin K intake will be determined during the study visits using dietary questionnaire.

Inclusion Criteria:

• treated with anticoagulants
• INR range between 2-3
• TTR (time in therapeutic range)equal or higher 56% during the 4 months before the inclusion

Exclusion Criteria:

• consumption of significant amounts of products conatining vitamin K
• regular consumption of dietary supplements susceptible to contain vitamin K
• milk intolerant or refusing a daily consumption of dairy product
• previous insufficient earlier therapeutic VKA follow-up
• cardiac, renal or severe respiratory insufficiency, diseases interfering fat absorption, significant abnormalities in safety parameters, clinically significant thrombotic or hemorrhagic event