Despite vitamin K2 accounts for about 25% of the total vitamin K intake, people have been considering vitamin K1 only for years. But how many types of vitamin k actually exist? Well, three:
Phylloquinone (K1), which is synthesized by plants, it is involved in blood coagulation;
Menaquinone (K2), which is synthesized by bacteria, it has not been completely characterized yet and can have multiple functions spanning from bone health to cardiovascular disease prevention. I will tell you more about its functions in my next post;
Dihydrophylloquinone, which is formed during the commercial hydrogenation of plant oils.
Natto (a fermented Japanese type of food) is considered the most concentrated source of vitamin K2. However, this vitamin has several isoforms (named MK-4 up to MK-10) and natto most only contains 4 of them: MK-5, MK-6, MK-7 (the one natto contains at highest concentrations) and MK-8. More details about vitamin K2-rich food on Vermeer et al., Nutrients, 2018.