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[Vitamin K and Bone Update. In vivo Metabolism of Vitamin K. - In relation to the conversion of vitamin K(1) to MK-4 -] Okano T, Nakagawa K, Kamao M. Clin Calcium. 2009 Dec;19(12):1779-87. Japanese. PMID: 19949269 Phylloquinone is a major form (>90%) of dietary vitamin K, but the form of vitamin K that exists at the highest concentrations in tissues of animals and humans is menaquinone-4 (MK-4) . Despite this great difference, the origin of tissue MK-4 had not been clarified until recently. We demonstrated that deuterium-labeled phylloquinone was converted into deuterium-labeled MK-4 in mice and this conversion occurred following an oral or enteral administration, but not parenteral administration. By the oral route, the phylloquinone with the deuterium-labeled side chain (phytyl side-chain) was clearly converted into menaquinone-4 with a non-deuterium-labeled side chain (geranylgeranyl side-chain) , implying that phylloquinone was converted into menaquinone-4 via integral side-chain removal. Our results suggest that cerebral menaquinone-4 originates from phylloquinone intake and the release of menadione from phylloquinone in the intestine followed by the prenylation of menadione into menaquinone-4 in the intestine or tissues

Conversion of phylloquinone (Vitamin K1) into menaquinone-4 (Vitamin K2) in mice: two possible routes for menaquinone-4 accumulation in cerebra of mice.\nOkano T, Shimomura Y, Yamane M, Suhara Y, Kamao M, Sugiura M, Nakagawa K.\nJ Biol Chem. 2008 Apr 25;283(17):11270-9. Epub 2007 Dec 14. \nPMID: 18083713 \ndoi: 10.1074/jbc.M702971200 \n\nOur results suggest that cerebral menaquinone-4 originates from phylloquinone intake and that there are two routes of accumulation, one is the release of menadione from phylloquinone in the intestine followed by the prenylation of menadione into menaquinone-4 in tissues, and another is cleavage and prenylation within the cerebrum.

Tissue phylloquinone and menaquinones in rats are affected by age and gender. Huber AM, Davidson KW, O'Brien-Morse ME, Sadowski JA. J Nutr. 1999 May;129(5):1039-44. PMID: 10222397 The results suggest that in extrahepatic tissues, certain menaquinones may be the predominant form of vitamin K. The specific tissue distribution and the general decline of MK-4 and MK-6 in extrahepatic tissues during aging suggest a vitamin K tissue dynamic that is affected not only by diet, but also by gender, age and the specific roles of phylloquinone, MK-4 and MK-6 in metabolism. All of these factors must be taken into account in establishing the nutrient requirement for vitamin K.

Mechanisms underlying the biphasic effect of vitamin K1 (phylloquinone) on arterial blood pressure.\nTirapelli CR, Resstel LB, de Oliveira AM, Corrêa FM.\nJ Pharm Pharmacol. 2008 Jul;60(7):889-93.\nPMID: 18549675 \nDOI: 10.1211/jpp.60.7.0010\n

Determination of Phylloquinone and Menaquinones in Foods by HPLC\n\nTerhi Koivu-Tikkanen\n\nAcademic Dissertation, January 2001. \nUniversity of Helsinki, Faculty of Agriculture and Forestry, \nDepartment of Applied Chemistry and Microbiology

Conversion of dietary phylloquinone to tissue menaquinone-4 in rats is not dependent on gut bacteria. Davidson RT, Foley AL, Engelke JA, Suttie JW. J Nutr. 1998 Feb;128(2):220-3. PMID: 9446847 These data offer conclusive proof that the tissue-specific formation of MK-4 from K is a metabolic transformation that does not require bacterial transformation to menadione as an intermediate in the process

Age and dietary form of vitamin K affect menaquinone-4 concentrations in male Fischer 344 rats. Booth SL, Peterson JW, Smith D, Shea MK, Chamberland J, Crivello N. J Nutr. 2008 Mar;138(3):492-6. PMID: 18287355 These data suggest that dihydrophylloquinone, which differs from phylloquinone in its side phytyl chain, is absorbed but its intake results in less MK-4 in certain tissues. Dihydrophylloquinone may be used in models for the study of tissue-specific vitamin K deficiency

Vitamin K content of foods and dietary vitamin K intake in Japanese young women. Kamao M, Suhara Y, Tsugawa N, Uwano M, Yamaguchi N, Uenishi K, Ishida H, Sasaki S, Okano T. J Nutr Sci Vitaminol (Tokyo). 2007 Dec;53(6):464-70. PMID: 18202532 Several reports indicate an important role for vitamin K in bone health as well as blood coagulation. However, the current Adequate Intakes (AI) might not be sufficient for the maintenance of bone health. To obtain a closer estimate of dietary intake of phylloquinone (PK) and menaquinones (MKs), PK, MK-4 and MK-7 contents in food samples (58 food items) were determined by an improved high-performance liquid chromatography method. Next, we assessed dietary vitamin K intake in young women living in eastern Japan using vitamin K contents measured here and the Standard Tables of Food Composition in Japan. PK was widely distributed in green vegetables and algae, and high amounts were found in spinach and broccoli (raw, 498 and 307 microg/100 g wet weight, respectively). Although MK-4 was widely distributed in animal products, overall MK-4 content was lower than PK. MK-7 was observed characteristically in fermented soybean products such as natto (939 microg/100 g). The mean total vitamin K intake of all subjects (using data from this study and Japanese food composition tables) was about 230 microg/d and 94% of participants met the AI of vitamin K for women aged 18-29 y in Japan, 60 microg/d. The contributions of PK, MK-4 and MK-7 to total vitamin K intake were 67.7, 7.3 and 24.9%, respectively. PK from vegetables and algae and MK-7 from pulses (including fermented soybean foods) were the major contributors to the total vitamin K intake of young women living in eastern Japan

Menaquinone-4 concentration is correlated with sphingolipid concentrations in rat brain. Carrié I, Portoukalian J, Vicaretti R, Rochford J, Potvin S, Ferland G. J Nutr. 2004 Jan;134(1):167-72. PMID: 14704312

Genetic and non-genetic correlates of vitamins K and D.\nShea MK, Benjamin EJ, Dupuis J, Massaro JM, Jacques PF, D'Agostino RB Sr, Ordovas JM, O'Donnell CJ, Dawson-Hughes B, Vasan RS, Booth SL.\nEur J Clin Nutr. 2007 Nov 21. [Epub ahead of print]\nPMID: 18030310 \ndoi: 10.1038/sj.ejcn\n\n