I downloaded a book suggested on here: 'K2 & the Ca Paradox'. It makes for extremely interesting reading but doesn't recommend a daily dosage.
The author stated a portion of natural Natto would usually be 400 mcg but usual supplement of K2 is 120 mcg but safe enough to double this amount.
The one I ordered is only 100 mcg and recommends taking 1 tablet in the evening. Looked at different sites and many say at least 150 mcg per day. So a bit confused on the optimum dosage. Online K2 seems to offer 100 mcg up to even a whopping 600 mcg so wondering what others consider the best option.