Vitamin K & the Colon

Vitamin K was first discovered in 1929 by Henrik Dam, a Danish biochemist with the University of Copenhagen. The blood-clotting capabilities of the vitamin were found in an experiment with feeding chicks a cholesterol-free diet. The chicks developed a hemorrhagic disease that was cured by a compound he identified as the "koagulationsvitamin" or vitamin K.

Phylloquinone

Phylloquinone, or K-1, is the dietary source of vitamin K. It is found in plant foods, primarily leafy green vegetables, and is believed to be the major source of the vitamin. Phylloquinone is produced in the photosynthetic tissue of the plant and the amount varies between vegetables. According to the "Journal of Food Composition and Analysis" from the USDA, geographical location, climate, soil condition and stage of maturation influence the amount of phylloquinone in plants.

Menaquinone

Menaquinone, also known as vitamin K-2, is synthesized in the lower intestines by bacteria, absorbed through the colon and found in the liver. Types of menaquinone-producing bacteria are Bacteroides fragilis, Eubacterium, Propionibacterium and Arachnia. These bacteria are believed to produce enough vitamin K to meet the daily requirements for both men and women, however the amount of absorption of menaquinone varies between individuals.

Research

In general, the functions of vitamin K are blood clotting and bone development. It is also speculated that menaquinone plays a role in reducing the risk of coronary heart disease, or CHD. The "Journal of Nutrition" published the Rotterdam study, a research project conducted at the Erasmus Medical Center, Rotterdam. The research shows the participants that received mid to high levels of dietary menaquinone had a reduced relative risk of CHD mortality. The intake of menaquinone was also related to all-cause mortality and aortic calcification. This research suggests that adequate intake of menaquinone is beneficial in CHD prevention. While the results from the Rotterdam study are encouraging, further research is needed to determine the full effects of dietary menaquinone.

Menaquinone Deficiency

Vitamin K deficiencies are rare as the body synthesizes the vitamin in the intestines. Menaquinone deficiencies occur in populations of people suffering from liver damage or disease such as alcoholics and those with cystic fibrosis. Newborns are at risk due to their diet consisting solely of milk, which is low in vitamin K, and their intestines have yet to contain the menaquinone-producing bacteria. People with renal insufficiency and chronically treated with antibiotics are also at risk for menaquinone deficiency.