Vitamin K is one of those lesser known nutrients that doesn’t get the same amount of attention as vitamins C and D. You might know vitamin K as the one that is given to newborns in hospital to help with blood clotting, and indeed this is one of vitamin K’s many important functions. There are a group of proteins in the body called Vitamin-K dependent proteins and coagulation factors (involved in blood clotting) are just some of these.
Vitamin K is a family of small, fat-soluble molecules. Vitamin K1 is found in green leafy vegetables (e.g. broccoli, kale, Brussels sprouts, cabbage) and is converted in the gut into the active form, vitamin K2. Vitamin K2 is also found in some meat, eggs, cheese and yogurt. It is also found in fermented soybeans, which is enjoyed in Japan in a food called natto – probably not something you’re likely to find in your local store!
Other vitamin K dependent proteins include osteocalcin which binds calcium in the bone. Osteocalcin is inactive and needs vitamin K to be fully activated. Consequently, vitamin K is very important for healthy bones.
Another important area is cardiovascular health. This is because vitamin K is needed in Gla proteins to prevent the cascade leading to calcification of blood vessels. Vitamin K deficiency is associated with increased artery calcification, which may lead to cardiovascular disease.
So you can see that vitamin K is important in many different areas of the body. You should be able to get all the vitamin K you need by eating a healthy balanced diet. It is important to note that certain medications, e.g. warfarin, have their action affected by vitamin K. If you are on warfarin, you need to eat about the same amount of vitamin K each day and should not adjust this without speaking to your doctor first.