It contains a synergistic combination of vitamin D and vitamin K with their active variants (D3 + K2) in a natural lipophilic composition. The two natural forms of vitamin K are vitamin K1 (phylloquinone) and vitamin K2 (menaquinone (MKs or MK-n). Vitamin K1 occurs in various green vegetables and vegetable oils and is the main dietary source of vitamin K. Vitamin K1 is present in the chloroplast membrane of leafy green vegetables. Vitamin K2 has a variable side chain length from four to 15 isoprene units and is referred to as MK-n, where n denotes the number of isoprenoid units. A small amount of MK-4 is found in animal products such as eggs, meat and liver.