Vitamin K

Vitamin K is needed primarily for the blood-clotting mechanism which prevents bleeding to death from cuts and wounds or internal bleeding.

Sources: Vitamin K is found naturally in plants and can be produced by bacteria in the intestine. The best dietary sources are green leafy vegetables such as spinach, sprouts, broccoli and cauliflower. Lower levels are found in liver, lean meat, cow's milk, egg yolk and wholewheat products.

Below: A microscopic picture of vitamin K

Vitamin K occurs in three forms:

• Vitamin K1 (phylloquinone, phytonadione, phytomenadione) is found in plants.
• Vitamin K2 (menaquinone) is synthesized by bacteria in the human and animal intestine.
• Vitamin K3 (menadione) is a synthetic compound that can be converted to K2 in the intestinal tract.

Functions: The vitamin's main function is as part of the blood clotting system which prevents excessive blood loss due to cuts, wounds or following an operation. Vitamin K is needed to make a protein called prothrombin which is the first stage in blood clotting and wound healing. Scientists also believe that a vitamin K dependent protein may be needed for healthy bone mineralisation.
The diet of farm animals needs to be fortified with vitamin A for optimum health, performance and fertility. This is because the beta-carotene content of green fodder plants drops rapidly after harvest.

Deficiency: Shortages of vitamin K are very rare but individuals suffering from liver disease or who are unable to absorb fat are at risk. New born babies have low stores of vitamin K. They may be at risk of vitamin K shortage since breast milk contains low levels and new babies are unable to make vitamin K in their intestines.

Product forms: DSM forms of vitamin K are K1 (oil or powder) for baby food and dietetic products, and K3 for animal nutrition.