Naturally occurring fat-soluble vitamin, needed for normal blood clotting
Helps protect against osteoporosis, may inhibit some tumors, aids in reducing menstrual flow.
Vitamin K is necessary for formation of prothrombin required for blood clotting, the functioning of several proteins involved in blood clotting, called coagulation. Essential for normal liver functioning and important in maintaining vitality and longevity. also aids the absorption of calcium in bone. Reduces excessive menstrual flows and prevents internal bleeding and hemorrhages. •
Vitamin K exists naturally in 4 forms;
K1 (phylloquinone) in green vegetables and
K2 (menaquinone) produced by intestinal bacteria and
K3 is menadione
K4 is another menadione. Vitamin K1, K2 and K3 are fat soluble and Vitamin K4 is water soluble. When administered, vitamin K3 is alkylated to one of the vitamin K2 forms of menaquinone.
A required coenzyme for the vitamin K-dependent carboxylase that catalyzes the carboxylation of the amino acid, glutamic acid, resulting in its conversion to gamma-carboxyglutamic acid (GLA). Gamma-carboxylation occurs only on specific glutamic acid residues in a few proteins, it is critical to the calcium-binding function of these proteins.
There are 2 naturally occurring forms of it. Plants synthesize phylloquinone, known as vitamin K1. Bacteria synthesize a range of different K forms, using repeating 5-carbon units in the side chain of the molecule. These forms of vitamin K are designated menaquinone-n (MK-n), where n stands for the number of 5-carbon units. MK-n are collectively referred to as vitamin K2. MK-4 is not produced in significant amounts by bacteria, but appears to be synthesized by animals (including humans) from phylloquinone. MK-4 is found in a number of organs other than the liver at higher concentrations than phylloquinone. There may be a unique function of MK-4 that is yet discovered.
Three vitamin-K dependent proteins have been isolated in bone. Osteocalcin is a protein synthesized by osteoblasts (bone forming cells). The synthesis of osteocalcin by osteoblasts is regulated by the active form of vitamin D, 1,25(OH)2D3 or calcitriol. The mineral-binding capacity of osteocalcin requires vitamin K-dependent gamma-carboxylation of three glutamic acid residues. The function of osteocalcin is thought to be related to bone mineralization. Matrix Gla protein (MGP) has been found in bone, cartilage, and soft tissue, including blood vessels. The results of animal studies suggest MGP prevents the calcification of soft tissue and cartilage, while facilitating normal bone growth and development. The vitamin K-dependent anticoagulant protein S is also synthesized by osteoblasts.
History: The "K" is derived from the German word "koagulation". Phylloquinone (vitamin K1) and menaquinones (vitamins K2) are the major dietary forms of vitamin K.
Technicals: The major function of the K vitamins is in the maintenance of normal levels of the blood clotting proteins, factors II, VII, IX, X and protein C and protein S, which are synthesized in the liver as inactive precursor proteins. Conversion from inactive to active clotting factor requires a posttranslational modification of specific glutamate (E) residues. This modification is a carboxylation and the enzyme responsible requires vitamin K as a cofactor. The resultant modified E residues are g-carboxyglutamate (gla). This process is most clearly understood for factor II, also called preprothrombin. Prothrombin is modified preprothrombin. The gla residues are effective calcium ion chelators. Upon chelation of calcium, prothrombin interacts with phospholipids in membranes and is proteolysed to thrombin through the action of activated factor X (Xa).
During the carboxylation reaction reduced hydroquinone form of vitamin K is converted to a 2,3-epoxide form. The regeneration of the hydroquinone form requires an uncharacterized reductase. This latter reaction is the site of action of the dicumarol based anticoagulants such as warfarin.
Sources: Kelp, alfalfa, green plants, leafy green vegetables, cow's milk, yogurt, egg yolks, blackstrap molasses, polyunsaturated oils, fish liver oils. Green leafy vegetables and some vegetable oils (soybean, cottonseed, canola, and olive) are all major contributors.
Hydrogenation of vegetable oils may decrease the absorption and biological effect of dietary vitamin K
Signs or Symptoms of a Deficiency: Naturally occurring vitamin K is absorbed from the intestines only in the presence of bile salts and other lipids through interaction with chylomicrons. Therefore, fat malabsorptive diseases can result in vitamin K deficiency. The synthetic vitamin K3 is water soluble and absorbed irrespective of the presence of intestinal lipids and bile. Since the vitamin K2 form is synthesized by intestinal bacteria, deficiency of the vitamin in adults is rare. However, long term antibiotic treatment can lead to deficiency in adults. The intestine of newborn infants is sterile, therefore, a deficiency in infants is possible if lacking from the early diet. The primary symptom of a deficiency in infants is a hemorrhagic syndrome.
The statements on this Web site have not been evaluated by the Food and Drug Administration (FDA). And are not intended to diagnose, treat, cure or prevent disease. The information presented is not intended to replace medical advice or treatment from your own doctor or healthcare provider. Nothing presented here is intended as a substitute for prescription medication or any other medical treatment prescribed by your doctor.