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Study Unlocks Which Form Of K2 Has Higher Bioavailability


The Law & Order Admin
Jan 4, 2012
http://www.swansonvitamins.com/ru-artic ... mobile=off

Study Unlocks Which Form of K2 Has Higher Bioavailability
November 27, 2012

Consuming vitamin K2 in its MK-7 form is better for raising levels of the vitamin in serum than K2 in the MK-4 form, says a new study from Japan and the Netherlands.

The results indicate that the "nutritional values of vitamin K2 homologues should be differentiated with regard to bioavailability and efficacy," wrote scientists from Maastricht University in The Netherlands and Kagawa Nutrition University in Japan in the Nutrition Journal.

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% of the vitamin K in a typical Western diet; and menaquinones (vitamin K2), which make up about 10% of Western vitamin K consumption and can be synthesized 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 also a rich source of MK-7.

"Because all vitamin K homologues can be converted to MK-4 in vivo, MK-4 is considered to have specific functions other than gamma-carboxylation of vitamin K-dependent proteins," explained the researchers.

"In this study, we demonstrated that a nutritional dose of MK-7 is well absorbed in humans, and significantly increases serum MK-7 levels, whereas MK-4 had no effect on serum MK-4 levels."

The researchers tested the effects of a single dose of MK-4 (420 mcg) or MK-7 (420 mcg) consumed with a standardized breakfast in 10 healthy Japanese women. Results showed that MK-7 was well absorbed and was measurable in serum samples up to two days after consumption. MK-4 was not detectable in serum.

A second study that used consecutive administration of MK-4 (60 mcg) or MK-7 (60 mcg) for seven days again with 10 healthy Japanese women indicated again that MK-4 did not increase MK-4 levels. On the other hand, MK-7 was found to increase MK-7 levels.

"The current study shows that MK-4 has a poor bioavailability at a nutritional level dose, whereas MK-7 is well absorbed and detectable in the blood at nutritional levels," the researchers wrote.

"In a previous rat study from our group, the intake of a nutritional dose of MK-4 did not increase the MK-4 levels in extrahepatic tissues, whereas MK-7 significantly increased MK-4 in extrahepatic tissues," they added. "Thus, MK-7 is a better supplier for MK-4 in vivo than MK-4 itself."

Nutrition Journal 11(1):93, 2012


therefore, the opposite is true? (happens often in medical studies)
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Aug 9, 2012
That is kinda interesting. I guess this is why Ray recommends Super-K, because it's not entirely clear which one will turn out to be better overall.
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Nov 25, 2012
One potential issue is that all of the commercial K2 MK7 I've been able to find is soy (Natto) derived, and hence may have phytoestrogenic effects.

I wish we knew what the "standardized breakfast" is. I know for certain at least the MK4 is fat soluble and should be taken with a fat-containing meal. The Thorne MK4 is sold as a solution in MCT oil.
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Nov 26, 2012

When I asked Peat which supplement will be good for my crohn's (beside thyroid) he told me that either Carlson or life extension's vitamin K should be good.
So, like you said, super K is a mixed of K1 and K2 from mk4 and mk7 but Carlson is only mk4.
And, so far, I don't know what to pick so I rotate between the two....
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