MK-4 is the major form of Vitamin K in vertebrate animals, including humans and common forms of meat animals. It is produced via conversion of vitamin K1 in the body, specifically in the testes, pancreas and arterial walls.[2] The conversion is not dependent on gut bacteria, occurring in germ-free rats[3][4] and in parenterally-administered K1 in rats.[5][6] Tissues that accumulate high amounts of MK-4 have a capacity to convert up to 90% of the available K1 into MK-4.[3][4][dubious – discuss]
Menatetrenone is approved in Japan for second-line treatment of postmenopausal osteoporosis. Evidence is restricted to small-scale RCTs; the minimum effective dose (for bone mass parameters) is 45 mg, much higher than the Daily Value for vitamin K (80 μg).[8]
420 μg of oral MK-4, in a single-dose or spread out over 7 days, does not cause detectable changes in serum MK-4 level in healthy women, whereas MK-7 produces the expected increases in MK-7 levels.[1]
The minimum effective oral dose to change serum osteocalcin levels is 1500 μg/d, where as oral MK-7 is effective on this parameter at 45 μg/d, a level more in line with nutritional intake. In addition, rat studies show that oral MK-7 is better at increasing extrahepatic tissue levels of MK-4 than oral MK-4.[1]
^ abRonden JE, Drittij-Reijnders MJ, Vermeer C, Thijssen HH (January 1998). "Intestinal flora is not an intermediate in the phylloquinone-menaquinone-4 conversion in the rat". Biochimica et Biophysica Acta (BBA) - General Subjects. 1379 (1): 69–75. doi:10.1016/S0304-4165(97)00089-5. PMID9468334.
^Iwamoto J (May 2014). "Vitamin K2 therapy for postmenopausal osteoporosis". Nutrients. 6 (5): 1971–80. doi:10.3390/nu6051971. PMC4042573. PMID24841104. administered daily doses of 15, 45, 90, and 135 mg revealed that 45 mg was the minimum effective dose for improving bone mass parameters evaluated by microdensitometry and/or single photon absorptiometry in postmenopausal women with osteoporosis
Listen to this article (1 minute)
This audio file was created from a revision of this article dated 8 September 2012 (2012-09-08), and does not reflect subsequent edits.