Natural Factors Vitamin K + D - Bonus Size - 120 mcg of K2 & 1000 IU of D3 - Provides two major fat-soluble vitamins for bone and vascular health: bioactive and highly bioavailable D3 (cholecalciferol), and menaquinone-7 (MK-7) from natto beans. Helps improve bone health and prevents arterial calcification. Vitamin K has been found to help direct calcium to the areas of the body where it is needed, such as the skeleton, and away from areas where it could have a negative effect, such as the cardiovascular system. Vitamin D is critical for the proper metabolism and absorption of calcium in the bones, and Vitamins K and D have been shown to work synergistically to improve bone density.