Vitamin K is often known as the “clotting vitamin” because without it, blood would not clot… This statement alone should caution you because consuming too much of this fat soluble vitamin could cause you to develop a blood clot. The adequate intake (AI) of vitamin K for men is 120 micrograms and 90 micrograms for women daily as defined by the U.S. Institute of Medicine (1). Research on the relationship of vitamin K in to bone health is extremely premature; however many dietary supplement products market claims around bone health. There is little to no existing evidence suggesting that any form of vitamin K can prevent fractures at any stage of the lifecycle. Vitamin K2 has been marketed more than any other supplemental form of the vitamin despite null and/or irreproducible findings from clinical trials. The most common form of vitamin K2 (there are 12 forms) sold on the market for bone health is menaquinone-7. This form has a greater likelihood of contributing to blood coagulation, especially for those individuals on oral anticoagulants, and has a lack of long-term safety data.
Small clinical trials do consistently show that consuming recommended levels of vitamin K as defined above has the ability to slow coronary calcification (i.e. slow the progression of cardiovascular disease and resulting heart attacks); however no study to date has shown that one form of vitamin K is superior to another in this regard.
- Institute of Medicine. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, DC: National Academies Press. 2001.