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MK4 is produced via conversion of vitamin K1 in the body, in the testes, pancreas and arterial walls.[2] While major questions still surround the biochemical pathway for the transformation of vitamin K1 to MK4, studies demonstrate the conversion is not dependent on gut bacteria, occurring in germ-free rats[3][4] and in parenterally-administered K1 in rats.[5][6] In fact, tissues that accumulate high amounts of MK4 have a remarkable capacity to convert up to 90% of the available K1 into MK4.[7][8]
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