Vitamin K status in human tissues: tissue-specific accumulation of phylloquinone and menaquinone-4

Abstract

We measured the vitamin K status in postmortem human tissues (brain, heart, kidney, liver, lung, pancreas) to see if there is a tissue-specific distribution pattern. Phylloquinone (K1,) was recovered in all tissues with relatively high levels in liver, heart and pancreas (medians, 10·6 (4·8), 9·3 (4·2), 28·4 (12·8) pmol(ng)/g wet weight tissue); low levels (< 2 pmol/g) were found in brain, kidney and lung. Menaquinone-4 (MK-4) was recovered from most of the tissues; its levels exceeded the K1levels in brain and kidney (median, 2·8 ng/g) and equalled K1in pancreas. Liver, heart and lung were low in MK–4. The higher menaquinones, MK-6–11, were recovered in the liver samples (n6), traces of MK-6–9 were found in some of the heart and pancreas samples. The results show that in man there are tissue-specific, vitamin-K distribution patterns comparable to those in the rat. Furthermore, the accumulation of vitamin K in heart, brain and pancreas suggests a hitherto unrecognized physiological function of this vitamin.

Effects of the blood coagulation vitamin K as an inhibitor of arterial calcification

“…It is now confirmed by different research groups that the essential nutritional form of vitamin K, vitamin K 1 , derived from plants is, to different extents, converted to menaquinone-4 (MK4) in various extrahepatic tissues (14)(15)(16). In the brain the conversion is almost 100% (17) and Spronk et al (16) have shown a significant conversion in the aortic wall.…”

Recent trends in the metabolism and cell biology of vitamin K with special reference to vitamin K cycling and MK-4 biosynthesis

“…The low plasma concentrations of K 1 are mirrored by low tissue reserves. Adult liver concentrations of K 1 are approximately 10 pmol/g wet tissue ( 49,50 ). The median total liver pool of K 1 in British adults was estimated at about 20 nmol, but including MKs this rises to 200-300 nmol ( 11,49 ).…”

Vitamin K-dependent Proteins, Warfarin, and Vascular Calcification

“…Initial theories suggested that vitamin K1 was converted into vitamin K2 by indigenous intestinal bacteria, with subsequent absorption (22), yet more recent studies suggest that this structural transformation actually occurs independently of bacteria within the intestinal enterocyte (23). Although the exact pathway of vitamin K2 entry into the body is uncertain, it does seem to accumulate preferentially in peripheral tissues (24), with particularly high levels in brain, aorta, pancreas, and fat, and low levels in the liver (25). Transport mechanisms may partly explain this difference in tissue concentration (26).…”