Vitamin K2 is thought to reduce coronary calcification, thereby decreasing your risk of cardiovascular disease. However, studies have reported inconsistent results -- possibly because of the different effects of vitamin K1 (phylloquinone) and vitamin K2 (menaquinone or MK). Few studies have included both.
At least one study, however, has investigated the association of intake of phylloquinone and menaquinone with coronary calcification. The intake of both forms of the vitamin was estimated using a food-frequency questionnaire. It was found that K2 had an effect on coronary calcification, but K1 did not.
According to the study:
"This study shows that high dietary menaquinone [Ks] intake, but probably not phylloquinone [K1], is associated with reduced coronary calcification. Adequate menaquinone intakes could therefore be important to prevent cardiovascular disease."