0510 - Vitamin K2 (Menachinon-4 and Menachinon-7)

The most important naturally occurring fat-soluble vitamin K compounds are vitamin K1 (phylloquinone) and vitamin K2 (menaquinone). Menaquinone is considered to be the more effective K vitamin in humans. The half-life in the blood is about 1 to 4 hours for vitamin K1, but 48 to 72 hours for the more lipophilic vitamin K2 subtype menaquinone-7.
The physiological effects of vitamin K2 include: intrahepatic formation of the prothrombin complex (factors II, VII, IX, X), activation of protein C and protein S; extrahepatic formation of osteocalcin in the osteoblasts. Epidemiological studies indicate an inverse relationship between vitamin K2 intake and the incidence of cardiovascular disease and arteriosclerosis. Some studies suggest a positive preventive and therapeutic effect of vitamin K2 intake in neurodegenerative diseases and prostate cancer.
According to the Deutsche Gesellschaft für Ernährung (German Nutrition Society), the daily vitamin K requirement is approximately 1 μg/kg body weight. Vitamin K2 is found in chicken, egg yolk, dairy products, certain types of cheese and liver, for example. It is particularly abundant in Natto, a traditional Japanese food made from fermented soybeans.

Reduced: Malabsorption, bile duct obstruction, parenteral nutrition, bile fistulas, vitamin K antagonists.
Symptoms of deficiency: Hemorrhages. In newborns whose mothers were not sufficiently supplied with vitamin K, intracranial bleeding due to hypoprothrombinaemia may occur.
Increased: No alimentary or therapeutic overdosing is known, but the effect of oral anticoagulants of the coumarin type may be attenuated. This should be considered in particular when supplementing menaquinone-7.
Note: the quick value is better suited for (indirect) assessment of the vitamin K level. See also vitamin K1.