Vitamin K is one of the fat-soluble vitamins along with A, D, and E. Vitamin K1 (phylloquinone) is a required coenzyme for carboxylation of glutamic acid and is critical for calcium binding that is required for the activation of seven vitamin K dependent clotting factors, which include factors II (prothrombin), VII, IX, X, and protein Z, protein S, and C that regulate the coagulation cascade. These vitamin K dependent factors are synthesized in the liver, hence the bleeding issues that can occur with liver disorders.
Vitamin K2 (menaquinon) is made by gut bacteria in the gastrointestinal track and has a role in moving calcium into bone and away from deposition in blood vessel walls, thus reducing arteriosclerosis and building strong bones. There are two forms of K2:
– MK-4 (menaquinone-4) found in butter, egg yolks, and animal based foods.
– MK-7 (menaquinone-7) found in fermented foods and stays in the body longer.
The role of K2 in calcium metabolism works in concert with vitamin D needed for calcium absorption from the intestines and given the close interplay between calcium and magnesium, these two are often best given together.
Gas6 is a K-dependent protein found throughout the nervous system, heart, lungs, stomach, kidney, and cartilage. It seems to be involved in cell signaling and cellular growth. There may be a significant role in the developing and aging nervous system.
SYMPTOMS OF DEFICIENCY
Most symptoms of vitamin K deficiency involve easy bleeding or bruising, nose bleeds, and rarely, bleeding into the GI track with bloody or black stools, blood in the urine, or heavy menses for women. Infants and newborns can have a bleeding disorder called hemorrhagic disease of the newborn (HDN) that can be life threatening and hence the recommendation that all newborns get a shot of phylloquinone (vitamin K1).
The other symptoms of vitamin K deficiency seem to relate to the long term calcium build-up in the blood vessels (arteriosclerosis) and poor bone mineralization from inadequate deposition of calcium with resulting osteoporosis, and increased risk of fractures.
The anti-coagulants Coumadin and Warfarin deplete vitamin K and patients on these should not take extra vitamin K unless directed to do so by their physician.
Kale 1 cup 547 micrograms
Broccoli 420 micrograms
Parsley 324 micrograms
Swiss chard 299 micrograms
Spinach raw 120 micrograms
cooking oils 2-26 micrograms
SAFETY AND TOXICITY
Vitamin K1 and K2 are safe with no upper limits having been established. Vitamin K3 (menadione) can interfere with glutathione and can induce liver toxicity, jaundice, and hemolytic anemia.
The major toxicity (bleeding disorders) can occur when those taking anticoagulants (Warfarin and Coumadin) take vitamin K supplements.
No upper limits have been established for vitamin K.
Adequate Intake has been set at:
Teens and adults 90
RDA for vitamin K is 1 microgram per Kg (per 2.2 lbs.), with 80 micrograms a day for adults. Therapeutic doses have been safely used in studies from 100-500 micrograms.
Clearly, eating greens or broccoli will provide plenty and even therapeutic doses of vitamin K.
Read my blog on Vitamin K2, Vitamin D, Calcium, and Magnesium here…
Read my blog on why you need Vitamin K2 and how it interacts with calcium and vitamin D here…
Read my blog on why infants should get vitamin K at birth here…