Prothrombin is a plasma protein that is produced in the liver and converted to thrombin, an enzyme in the blood, during the clotting. Whenever a person has a bleeding wound, it is the vitamin K that causes the production of prothrombin to stop the bleeding, in fact, it is essential in enabling the blood to clot and help the body to repair injuries. It also converts glucose into glycogen, a white compound stored in the liver and muscles as a source of energy.

There are three different forms of this vitamin. The first, K1, also known as phylloquinone, an oily liquid found in leafy vegetables, bran, rice and pork liver and is essential for the clotting of blood. Secondly, K2, or menaquinone, is formed by friendly bacteria in the large intestines. Thirdly, K3 known as menadione is actually an artificial form. All three vitamins end up in the liver where it is used to create the blood clotting substances.

Side note: The body has a function in place to minimize a minor bump or cut in a healthy individual. This process is called hemostasis (stopping of bleeding through an organ or body part) by forming a clot that stops the blood flow. But in people with hemophilia, the blood does not clot because one or more of the proteins that forms the clot and repair injuries is defective or all together missing.

The best natural sources of vitamin K are green leafy vegetables, such as spinach, cabbage, cauliflower, broccoli, asparagus, egg yolks, blackstrap molasses, oatmeal, oats, rye, soybeans, and wheat. However, because the friendly bacteria in the intestine make one of the forms, it is extremely rare for a person to have a deficiency; and therefore the majority of people do not need supplements.

Apart from the main function of helping blood to clot, vitamin K1 has an important part to play in the bone building process. It is required to retain the calcium in the bones and redistribute it to where it is needed.

Although a K deficiency is relatively rare there are certain groups of people who may suffer from the lack of it. Newborn babies may not have enough because of insufficient bacteria in their intestines to produce it. The majority of newborn babies in developed countries are therefore given a vitamin K injection to tie them over until the natural process takes effect.

This is one of the few times a supplement will be taken by most people throughout their lives. Due to the decreased absorption of vitamin K in the elderly, a supplement is needed. Antibiotics may lead to a deficiency due to the fact that the antibiotics interfere with the absorption of vitamin K and kill the intestinal bacteria, the good and the bad.

Vitamin K will prevent the excretion of calcium in urine, and may accelerate the healing of factures and enhance the immune system. It promotes a healthy liver function, may help prevent certain cancers, help prevent osteoporosis and may increase resistance of infection.