Nattokinase I am not, although if that relates to the natto chinese dish I have heard that is a natural K2 source.

We have taken a supplement of D3 and K2 combined #mce_temp_url# for over four years now. I also eat sauerkraut probably average once a week most of the time also, which has K2. The first link is for pills. Before we did those we used drops #mce_temp_url#. 

If we take D3 I definitely want K2 with it also.

Wife and I Vitamin D 25 hydroxy tests run up around 75 (mine was 85.3 just recently, last year around 70 or so) which is right where I want to see them. At least 50 and up around 100 is fine too. If I was above100 I would probably back off on the supplement for a while. We do not always take the supplement in the summer and have backed off after we got the last test.

I probably should get some K2 pills and take just them. We have had them in the past before I learned the D3/K2 pills are no higher than just the K2 alone. So we just started taking the combo pill. K2 is what helps the calcium go to the right place (bones) and away from where it is not supposed to be (soft tissue). At least that is my understanding. I'm no doctor. Don't even own a white coat.