Vitamin K2: Study unlocks which forms have higher bioavailability

By Stephen Daniells

- Last updated on GMT

Vitamin K2: Study unlocks which forms have higher bioavailability

Related tags Vitamin k Nutrition

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 J-Oil Mills, Inc., in Japan, University Maastricht in The Netherlands, and Kagawa Nutrition University in Japan in the Nutrition Journal​.

K forms

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 (vitamins K2), which make up about 10% 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.

“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 human, and significantly increases serum MK-7 levels, whereas MK-4 had no effect on serum MK-4 levels.

Study details

The researchers tested the effects of a single dose of MK-4 (420 micrograms) or MK-7 (420 micrograms) consumed with a standardized breakfast in ten health Japanese women. Results showed that MK-7 was well absorbed and was measurable in serum samples up to 2 days after consumption.

On the other hand, MK-4 was not measured in any of the women at any time, they said.

A second study that used consecutive administration of MK-4 (60 micrograms) or MK-7 (micrograms) for seven days again with ten health Japanese women indicated that MK-4 again 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,”​ wrote the researchers.

“In a previous rat study from our group [Vitamins (Japan) 2007, Vol. 81, pp. 377-381], 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.”

Source: Nutrition Journal
2012, 11​:93 doi:10.1186/1475-2891-11-93
“Comparison of menaquinone-4 and menaquinone-7 bioavailability in healthy women”
Authors: T. Sato, L.J. Schurgers, K. Uenishi

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Posted by Frederick Bach,

The statements inferring that it is sufficient to take in K2-7 in preference to K2-4 are incorrect in my personal experience. I was suffering from serious short-term Memory loss and a terribly stuffy feeling inside my head about where the hippocampus is. O started taking K2-7 for a broken arm. Helped a lot. Did nothing for my head. A year later I broke my leg. My wife found K2-7 AND K2-4 separately. I started with the -7 Dec 2014 still nothing with my head. Then in January I started the K2-4. Wow! The fog in my head lifted and disappeared. My short-term memory returned. I could remember the piano music I just read AFTER I closed the book! Certainly a spooky change. So I let the bottle of K2-4 run out. Symptoms returned. But before I got really bad again I got another bottle of K2-4. Problems went away again. I repeated this one more time. Then I wrote to Life Extension dot org.
They phoned me back. I related my story again. Then they told me they had a paper on that from 2012. I said "So you have known about this for 3 years?" "Yes". Then I said, "Why doesn't the world know about this? I'm telling everybody!" The point is the vegan K2-4 handled by Trophic removed my symptoms while a lot of K2-7 might have helped my bones and skin but didn't do anything for my head. Research that surfaced this year (2016) shows that K2-4 fills in for, or sisters up with, Co-Q10 in the brain especially, and some tissues prefer K2-4.

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vegetarian sources

Posted by Donald Spiderman Thomas,

As a vegetarian for 40 years, I am always amazed at the current trend in nutritional science. For so many years, vegetarian sources of many vitamins/minerals were considered inferior.heme iron was superior to non heme iron

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