Vitamin K1

Serum protected from light, 1ml

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. It can be partly replaced by phylloquinone, which is supplied by vegetable food when the intestinal flora is intact. 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 K1 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.
According to the Deutsche Gesellschaft für Ernährung (German Nutrition Society), the daily vitamin K requirement is approx. 1 μg/kg body weight. Vitamin K1 is found in virtually all green vegetables and is particularly abundant in kale, spinach, lettuce, fennel, Brussels sprouts and chickpeas.

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 K2.