Vitamin K

Synonyms. There are three derivatives of vitamin K : Phylloquinone (K1), Menaquinones (K2) and Menadione (K3). Phylloquinone (Kt) is the major form of vitamin K,

Antihaemorrhagic factor, Antihaemorrhagic vitamin, ‘Koagulation Faktor’ in Danish, Koagulation (coagulation) Vitamin.

Sources. Alfalfa grass (a clover-like plant used for fodder), spinach, cauliflower, cabbage, tomato, soyabean, wheat bran, wheat germ, whole wheat, vegetable oils, liver, pork, fish. It is

synthesized by bacteria in the large intestine (colon).Infact vitamin K1, is abundant in vegetable oils, leafy green vegetables and wheat bran. Vitamin K2 is synthesized by the intestinal bacteria.

Daily Requirement. About 0.07 to 0.14 mg.

Functions.

(i) It is necessary for the synthesis of prothrombin (the precursor of thrombin) in the liver for normal clotting of blood. Thus vitamin K helps in blood clotting, prevention of haemorrhage and excessive bleeding in wounds

(ii) It also plays role in mitochondrial electron transport and oxidative phosphorylation.

Deficiency Symptoms. Vitamin K deficiency causes a decrease in the prothrombin content of the blood, resulting faulty blood clotting. Thus a tendency to bleeding (haemorrhages) is observed.

Destroyed by : Prolonged use of antibiotics and sulpha drugs.

Hypervitaminosis K. Excess intake of vitamin K causes gastrointestinal disturbance and anaemia.

An important characteristic of fat-soluble vitamins is that these vitamins can be stored in the body in sufficient amounts, mostly in the liver. So their deficiency is not effective for long times.