A method for rapidly improving cardiovascular function, reducing arterial stiffness and reversing calcification of a blood vessel in a mammal comprising administering to the mammal an effective amount of vitamin K for a period of less than 6 months. Also a method for increasing endothelial nitric oxide production in mammals comprising administering to the mammal an effective amount of vitamin K for a period of less than 6 months. The vitamin K can be administered together with additional substances such as vitamin D.
