Vitamin K2 has higher bioavailability than K1

Vitamin K2 has higher bioavailability than K1

Nutraingredients . com | Europe
_Vitamin K2 higher bioavailability than K1_, say scientists
/By Stephen Daniells/

18/12/2006 - Vitamin K2 derived from the fermented soy product natto has a
higher bioavailability than vitamin K1, results that may have implications
for functional food formulators.

The new study, published on-line ahead of print in the journal Blood and
partly funded by Natural ASA, reported that vitamin K2 in the form of
menaquinone-7 (MK-7) from natto was more effective in both promoting markers
of bone health, and counteracting vitamin K antagonists.
"For the food industry, an alternative to increasing the recommended dose
would be introducing on a larger scale the more potent MK-7 instead of K1 in
functional foods and multivitamin supplements," wrote lead author Leon
Schurgers.

There are two main forms of vitamin K: phylloquinone, also known as
phytonadione, (vitamin K1) which is found in green leafy vegetables such as
lettuce, broccoli and spinach, and makes up about 90 per cent of the vitamin
K in a typical Western diet; and menaquinones (vitamins K2), which make up
about 10 per cent of Western vitamin K consumption and can be synthesised in
the gut by microflora.

Menaquinones (MK-n: with the n determined by the number of prenyl side
chains) can also be found in the diet; MK-4 can be found in animal meat,
MK-7, MK-8, and MK-9 are found in fermented food products like cheese, and
natto is a rich source of MK-7.

Some sources have said that MK-4, also known as menatetrenone, is synthetic
vitamin K2, which is not correct. However, MK-4 is distinct from other MKs
because it not a major constituent of the spectrum of MKs produced by gut
microflora, but can be derived from K1 in vivo.

A synthetic form of vitamin K, known as K3, does exist but is not
recommended for human consumption.

"This is the first human study using natural vitamin K2 as a dietary
supplement. Clearly Natural Vitamin K2 as menaquinone-7 is the most
beneficial vitamin K that one could take. Large scale human studies have
shown that eating foods rich in Vitamin K2 significantly promotes bone
health, reduces risk of bone injury, and significantly promotes
cardiovascular health," said Schurgers in a release.

The findings from the new research, by researchers from the University of
Maastricht and the University Hospital Maastricht, were based on four
separate studies. The first of which looked at the bioavailability after
oral intake of both vitamin K1 (Konakion, Roche) and K2 (N-ZymeCeuticals) by
15 volunteers.

The Maastricht-based researchers report that both blood levels peaked after
four hours. However, the levels of vitamin K1 were 86 per cent lower after
only eight hours, while K2 (MK-7) levels were only 50 per cent lower after
68 hours, showing slower excretion from the body.

The second study involved ten volunteers given increasing doses of either K1
or K2. Four hours after consuming the supplement, blood levels of the
vitamins showed a dose-respondent effect, but only the K2 still had an
effect 24 hours later.

"This means that - if taken in single daily doses of 100 micrograms - only
MK-7 is effectively present in the circulation and available for absorption
by various tissues during the 24 hours following intake," wrote the
researchers.

Read the full story:
* w w w .nutraingredients . com /news/ng.asp?n=72867&m=2FSND19&idP=2&c=iuyfvgwnogplycn

Abstract of the study:
* w w w .ncbi.nlm.nih.gov/entrez/query.fcgi?tmpl=NoSidebarfile&db=PubMed&cmd=Retrieve&list_uids=17158229&dopt=Abstract

--
Juhana