Why are patient levels of K1 and K2 low despite taking K1 and K2 supplements?

Patient levels of K1 and K2 may be low despite supplementation for any or all of the following reasons. (1) Inconsistent supplementation of vitamin K1 and K2 (changing dose and/or frequency of supplementation). (2) Supplementation of K1 as phytonadione, not phylloquinone. Phytonadione is a synthetic form of K1.  (3) Supplementation of K2 as MK4, not MK7. (4) Low dietary intake of vitamin K1 and K2 (usually dairy free diets). (5) Use of antibiotics and antibacterial herbs that may inhibit bacterial production of vitamin K. (6) Use of bile acid sequestrants and binders that may reduce absorption of vitamin K. (7) Genetic single nucleotide polymorphisms of VKORC1 gene (Vibrant does not test for this).