Vitamin K: Double Bonds beyond Coagulation Insights into Differences between Vitamin K1 and K2 in Health and Disease
Division of Nephrology, RWTH Aachen University, 52074 Aachen, Germany
Department of Biochemistry, Cardiovascular Research Institute Maastricht, 6200MD Maastricht, The Netherlands
NattoPharma ASA, 0283 Oslo, Norway
International Science & Health Foundation, 30-134 Krakow, Poland
Author to whom correspondence should be addressed.
These authors contributed equally to this work.
Int. J. Mol. Sci. 2019, 20(4), 896; https://doi.org/10.3390/ijms20040896
Received: 24 January 2019 / Revised: 15 February 2019 / Accepted: 16 February 2019 / Published: 19 February 2019
(This article belongs to the Special Issue Molecular Aspects of the Action of Vitamin K and its Related Compounds)
Vitamin K is an essential bioactive compound required for optimal body function. Vitamin K can be present in various isoforms, distinguishable by two main structures, namely, phylloquinone (K1) and menaquinones (K2). The difference in structure between K1 and K2 is seen in different absorption rates, tissue distribution, and bioavailability. Although differing in structure, both act as cofactor for the enzyme gamma-glutamylcarboxylase, encompassing both hepatic and extrahepatic activity. Only carboxylated proteins are active and promote a health profile like hemostasis. Furthermore, vitamin K2 in the form of MK-7 has been shown to be a bioactive compound in regulating osteoporosis, atherosclerosis, cancer and inflammatory diseases without risk of negative side effects or overdosing. This review is the first to highlight differences between isoforms vitamin K1 and K2 by means of source, function, and extrahepatic activity.