Vitamin K

Vitamin K (K from "Koagulations-Vitamin" in German, Danish, Swedish and Norwegian) denotes a group of lipophilic, hydrophobic vitamins that are needed for the posttranslational modification of certain proteins, mostly required for blood coagulation. Chemically they are 2-methyl-1,4-naphthoquinone derivatives.
Vitamin K2 (menaquinone, menatetrenone) is normally produced by bacteria in the intestines, and dietary deficiency is extremely rare unless the intestines are heavily damaged or are unable to absorb the molecule.

Sources of Vitamin K

Vitamin K is found chiefly in leafy green vegetables such as spinach, swiss chard, and Brassica (e.g. cabbage, kale, cauliflower, broccoli, and brussels sprouts); some fruits such as avocado and kiwifruit are also high in Vitamin K. By way of reference, two tablespoons of parsley contain 153% of the recommended daily amount of vitamin K. Some vegetable oils, notably soybean, contain vitamin K, but at levels that would require relatively large caloric consumption to meet the USDA recommended levels.
Phylloquinone (vitamin K1) is the major dietary form of vitamin K.
Menaquinone-4 and Menaquinone-7 (vitamin K2) are found in meat, eggs, dairy and natto. MK-4 is synthesized by animal tissues, the rest (mainly MK-7) are synthesized by bacteria during fermentation. In natto 0% of vitamin K is from MK-4 and in cheese 2-7%.

Role in disease/deficiency

Vitamin K-deficiency may occur by disturbed intestinal uptake (such as would occur in a bile duct obstruction), by therapeutic or accidental intake of vitamin K-antagonists or, very rarely, by nutritional vitamin K-deficiency. As a result, Gla-residues are inadequately formed and the Gla-proteins are insufficiently active. Lack of control of the three processes mentioned above may lead to the following: risk of massive, uncontrolled bleeding, cartilage calcification and severe malformation of developing bone, or deposition of insoluble calcium salts in the walls of arteries. The deposition of calcium in soft tissues, including arterial walls, is quite common, especially in those suffering from atherosclerosis, suggesting that Vitamin K deficiency is more common than previously thought. Menaquinone, but not phylloquinone, intake is associated with reduced risk of CHD mortality, all-cause mortality and severe aortic calcification.
In a cohort study in Germany (11319 men, mean follow-up time 8.6y), Menaquinone intake was associated with decreased incidence of advanced prostate cancer.
Postmenopausal and elderly women in Thailand have high risk of Vitamin K2 deficiency, comparing to the normal value of young, reproductive females. Current dosage recommendations for Vitamin K may be too low.
According to a study published in the October 14, 2008 edition of PLoS Medicine, Vitamin K does not protect against age-related decreasing bone density, but may protect against fractures and cancers in postmenopausal women.

Use on newborn babies

In some countries, Vitamin K is routinely given to newborn babies, orally or by injection. Vitamin K is used as prophylactic measure to prevent late-onset haemorrhagic disease (HDN). As HDN is relatively rare, some parents decline Vitamin K protocol for their newborn; most pediatricians, however, highly recommend the prophylactic dose for adequate protection. Newborns have the right amount of Vitamin K in their bodies at about eight days of age, unless HDN runs in your family, Vitamin K injections are not necessary. If you still feel it is needed, you may use an oral Vitamin K, which does not harm the newborn in any way.

Vitamin K is found in the following products:

APHRO-VITA