Ann K., who reads this column in the Monterey Herald, writes:
“Dear Barbara, I read your column on vitamin K. I am a 75-year-old woman who takes warfarin daily because of an arterial clot. I have been told not to take vitamin K. Here is my question: Can I take vitamin K2 for bone health and not worry about it having an adverse impact on my INR or causing clotting? Thanks for your response.”
Dear Ann: First, I would follow your medical provider’s orders. They know your complete medical condition much better than I do. That said, here is more information on vitamin K2, also known as menaquinone (MK). (Various versions of vitamin K2 include MK-4, 7 or 9.)
As I mentioned in a previous column, vitamin K is necessary to help our blood clot normally — which comes in handy when we are injured, to prevent us from bleeding to death.
Warfarin has the opposite effect on blood clotting. It helps thin the blood to prevent dangerous blood clots due to certain medical conditions.
Here’s the catch: Vitamin K is an essential nutrient that our bodies require for normal functioning. In other words, we need a certain amount of vitamin K, which includes K1 as well as K2. The current adequate intake set by the Institute of Medicine is 90 micrograms a day for women and 120 micrograms a day for men.