Whenever a person has a bleeding wound, it is the K vitamin present in the blood, that stops the bleeding and enables most minor cuts to heal quickly.
The first variant of the K vitamin is vitamin K1, also known as phylloquinone. This is the form of the K vitamin that is found in types of plant foods.
The second form of the K vitamin is the vitamin K2, or menaquinone. This type of the K vitamin is formed by friendly bacteria in the intestines.
Thirdly, there is vitamin K3 which is also known as menadione and is actually an artificial form of the K vitamin.
All three of these types of K vitamin end up in the liver where it is used to create the blood clotting substances.
The best natural sources of the K vitamin are green leafy vegetables, such as spinach. However, because the friendly bacteria in the intestine makes one of the forms of the K vitamin it is extremely rare for a person to have a deficiency of the K vitamin and so K vitamin supplements are not needed by the majority of people.
Apart from the main function of helping blood to clot, the K vitamin, specifically the Vitamin K1, has an important part to play in the bone building process. This K vitamin is required to retain the calcium in the bones and redistribute it to where it is needed.
Newborn babies may not have enough of the K vitamin as they have insufficient bacteria in their intestines to produce it. The majority of newborn babies in developed countries are therefore given a K vitamin injection to tide them over until the natural process takes over. That is the only time that a K vitamin supplement will be taken by most people throughout their lives.
However, an extended course of antibiotics may lead to a K vitamin deficiency due to the fact that the antibiotics kill the intestinal bacteria as well as the ones that they are being taken to cure. Again, a K vitamin supplement may be given if the course of antibiotics has to continue for a long period of time.
(supplement labels are strictly regulated regarding the claims that they can make, and at the time of writing, the list below are the only allowed health claims that can be made for vitamin B12 in the UK and the EU).
There are no UK / EU authorised health claims for Vitamin K.
UK NHS on B Vitamins: