Menaquinone

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Structural formula
Structure of menaquinone
General
Common name Vitamin K 2
other names
  • Farnoquinone
  • Menaquinone-n (n = 4 ... 9)
  • 2-methyl-3-difarnesyl-1,4-naphtoquinone
Molecular formula C 11 + 5 * n H 8 + 8 * n O 2 (n = 4 ... 9)
CAS number 84-81-1
PubChem 5283547
Brief description yellow liquid
Occurrence Egg yolks, butter, natto
physiology
function Synthesis of prothrombin
Daily need 0.065-0.08 mg / day
Consequences in case of deficiency Ecchymosis , petechiae , hematoma
Overdose not known
properties
Molar mass Cannot be specified, as a mixture of substances
Physical state liquid
solubility fat soluble
safety instructions
GHS labeling of hazardous substances
no classification available
H and P phrases H: see above
P: see above
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Menaquinone ( MK ) or vitamin K 2 is a fat-soluble vitamin which, together with the group of phylloquinones or phylloquinone- like substances, is collectively referred to as vitamin K for historical reasons .

Vitamin K is required for the synthesis of prothrombin , as a cofactor in the osteocalcin metabolism and the metabolism of the matrix Gla proteins. The name of the vitamin K group was derived from its indirect effect on blood clotting ( coagulation ). Today a distinction is made between different forms of the vitamin.

description

Menaquinone is u in the healthy body. a. formed by the bacteria of the intestinal flora . About half of the vitamin K requirement is provided in this way. As natto a consumed feed in eastern Japan from fermented soya is referred to, which is proven especially rich in natural menaquinone. As with the other vitamin K representatives, the presence of bile acids is required for absorption from the intestine .

Vitamin K 2 (menaquinone) has been approved for use in European food and dietary supplement preparations in addition to vitamin K 1 (phylloquinone) after testing by the European supervisory authority EFSA in 2009 . In addition, positive health claims for vitamin K were published. Due to insufficient documentation, submitted health claims regarding the protection of the vessels against arteriosclerosis were rejected by the EFSA.

The first hypotheses regarding a reduction in vascular calcification and mortality through adequate intake of menaquinone are based on data from the Rotterdam study from 2004. Here, however, menaquinone was not administered, as in controlled clinical studies, but rather what was determined by questionnaires people involved in the study consumed food and vitamins. The average daily amount was calculated from the daily food intake using data on the menaquinone content of the food. The relative risk of cardiovascular disease was reduced in the middle and upper thirds compared to the third with the lowest menaquinone consumption. The same was found for the total death rate. For taking phylloquinone, i. H. Vitamin K 1 , the Rotterdam study was unable to show any connection with the rate of cardiovascular disease or mortality. It was therefore hypothesized that an adequate intake of menaquinone could be important for the prevention of cardiovascular diseases.

In the recent past, studies have been carried out on people with renal insufficiency, in particular, with regard to an undersupply of menaquinone and the resulting consequences, since this group of people is significantly more affected by vascular calcifications and the resulting cardiovascular diseases and deaths than the normal population.

Initial pilot studies indicate that surrogate parameters (dephosphorylated / non-carboxylated MGP, non-carboxylated osteocalcin and PIVKA-II) as well as signs of calcification measurable with imaging procedures, such as the “Coronary Artery Calcium Score”, are associated with the supply of menaquinone. H. the calcification of the heart vessels, or the “Common Carotid intima medica thickness”, d. H. the condition of the carotid arteries.

dosage

The daily dose recommended by the EFSA, which does not differentiate between the intake of vitamin K 1 and K 2 , is age-dependent: while infants between 7 and 11 months should ingest about 10 µg vitamin K per day, the dose for people over 18 years of age is around 70 µg. At the beginning of 2017, this intake recommendation formulated in 1993 was confirmed again. The need for vitamin K 2 depends to a large extent on the functionality of the intestine, as various intestinal bacteria, including strains of Escherichia coli and Bacteroides fragilis , contribute significantly to the supply of the body with menaquinones. Different scientists postulate that between 10 and 50% of the vitamin K 2 requirement can be covered by intestinal self-production.

See also

literature

Web links

Individual evidence

  1. ↑ emedicine.medscape.com
  2. ↑ This substance has either not yet been classified with regard to its hazardousness or a reliable and citable source has not yet been found.
  3. ↑ MJ Shearer, X. Fu, SL Booth: Vitamin K nutrition, metabolism, and requirements: current concepts and future research. In: Advances in nutrition (Bethesda, Md.). Volume 3, number 2, March 2012, pp. 182-195, doi : 10.3945 / an.111.001800 . PMID 22516726 . PMC 3648719 (free full text).
  4. ↑ R. Bentley, R. Mega Nathan: Biosynthesis of vitamin K (menaquinone) in bacteria. In: Microbiological reviews. Volume 46, Number 3, September 1982, pp. 241-280, PMID 6127606 . PMC 281544 (free full text).
  5. ↑ JM Conly, K. Stein: The production of menaquinones (vitamin K2) by intestinal bacteria and their role in maintaining coagulation homeostasis. In: Progress in food & nutrition science. Volume 16, Number 4, 1992 Oct-Dec, pp. 307-343, PMID 1492156 .
  6. ↑ efsa.europa.eu: Vitamin K2 added for nutritional purposes in foods for particular nutritional uses, food supplements and foods intended for the general population and Vitamin K2 as a source of vitamin K added for nutritional purposes to foodstuffs, in the context of regulation (EC) N ° 258/97 - Scientific Opinion of the Panel on Dietetic Products, Nutrition and Allergies. doi : 10.2903 / j.efsa.2008.822
  7. ↑ REGULATION (EU) No. 432/2012 OF THE COMMISSION of 16 May 2012 (PDF)
  8. ↑ JM Geleijnse, C. Vermeer, DE Grobbee, LJ Schurgers, MH Knapen, IM van der Meer, A. Hofman, JC Witteman: Dietary intake of menaquinone is associated with a reduced risk of coronary heart disease: the Rotterdam Study. In: The Journal of Nutrition. Volume 134, Number 11, November 2004, pp. 3100-3105, PMID 15514282 .
  9. ↑ M. Fusaro, M. Noale, V. Viola, F. Galli, G. Tripepi, N. Vajente, M. Plebani, M. Zaninotto, G. Guglielmi, D. Miotto, L. Dalle Carbonare, A. D ' Angelo, A. Naso, C. Grimaldi, D. Miozzo, S. Giannini, M. Gallieni: Vitamin K, vertebral fractures, vascular calcifications, and mortality: Vitamin K Italian (VIKI) dialysis study. In: Journal of Bone and Mineral Research . Volume 27, Number 11, November 2012, pp. 2271–2278, doi : 10.1002 / jbmr.1677 . PMID 22692665 .
  10. ^ R. Westenfeld, T. Krueger, G. Schlieper, EC Cranenburg, EJ Magdeleyns, S. Heidenreich, S. Holzmann, C. Vermeer, W. Jahnen-Dechent, M. Ketteler, J. Floege, LJ Schurgers: Effect of vitamin K2 supplementation on functional vitamin K deficiency in hemodialysis patients: a randomized trial. In: American Journal of Kidney Diseases . Volume 59, Number 2, February 2012, pp. 186-195, doi : 10.1053 / j.ajkd.2011.10.041 . PMID 22169620 .
  11. ↑ I. Kurnatowska et al .: Effect of vitamin K substitution on vascular calcification and early atherosclerotic changes in patients with chronic kidney desease - preliminary results ( Memento from October 20, 2013 in the Internet Archive ) (PDF; 743 kB)
  12. ↑ Recommended dosage of the vitamin K2 balance. Vitalinstitut, accessed on February 9, 2018 (German).