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K2 (as MK-7) Improves Bone Health in Latest Study

In the newest study on vitamin K2 and bone health, 244 healthy postmenopausal women received for MK-7 (180 μg /day) or placebo  for 3 years.

Bone mineral density of lumbar spine, total hip, and femoral neck were measured, along with circulating uncarboxylated osteocalcin (ucOC) and carboxylated OC (cOC). From this data, bone strength indices of the femoral neck and the ucOC/cOC ratio (an indicator of vitamin K status) were calculated. Measurements occurred at baseline and annually during the study treatment period.

Results showed that MK-7 supplementation significantly improved vitamin K status and decreased the age-related decline in bone mineral content and density at the lumbar spine and femoral neck. Bone strength was also favorably affected by the vitamin. It also lowered levels of ucOC by 50% (compared to a 4% increase in the placebo group).

The researchers conclude, "MK-7 supplements may help postmenopausal women to prevent bone loss. Whether these results can be extrapolated to other populations, e.g., children and men, needs further investigation."

The significance of this study is that it shows that the bone benefits can be realized at relatively low doses (180 mcg/day, compared to 45,000 mcg/day in previous studies that used another form of K2 called MK-4). However, previous studies on low-dose MK-7 showed questionable benefits but the lack of benefit was often attributed to the short study period (since bone development is a long-term process). This 3-year study shows that when taken consistently, a lower "nutritional" dose of MK-7 is beneficial.

Just a word of caution though... while newer studies are showing that the vast bulk of the population is actually deficient--and should supplement--there is one group that should avoid it: that is people taking coumarin anticoagulants (like warfarin).

In fact, with respect to MK-7 specifically, another newly published study suggests doses as low as 10 mcg/day should be avoided in patients taking warfarin. This is actually much lower than a previous study that calculated up to 50 mcg/day of MK-7 altered INR (international normalized ratio, a measure of blood clotting) by less than 10% (meaning up to 50 mcg/day may have been safe). This new study shows even 10 mcg/day of MK-7 should be avoided if taking coumarins.


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  1. Hi Dr. Know,

    What is considered a 'nutritional dose' of MK-7? Have been taking 120mcg daily for over six months now. Is that adequate? Thanks.

    1. 120 mcg/day would be adequate. In fact, if we're looking specifically at MK-7, it seems doses as low as 45 mcg/day can sufficiently carboxylate (activate) osteocalcin. However, I'm not sure if this dose is sufficient to activate other vitamin K-dependent proteins, such as matrix Gla protein.

      Based on the details of the study design, the researchers and institute behind the study, and the dose administered, I would guess the results of the latest publication come from the same study I discussed last year where preliminary data showed MK-7 potentially reversing arterial calcification. At that time, it was only presented at a conference in Geneva. That post can be found here (link was also provide above under "Related posts").


      Now that it looks like the study has wrapped-up and results are being published, if the final results did in fact show a return of blood vessel elasticity (indicating reversal of arterial calcification), I would expect the results to be published shortly.

      As for the "nutritional dose," I am suggesting 180 mcg/day, which is the dose used in the study (even though 180 mcg/day would be difficult for most to obtain through diet alone), which seems to also provide cardiovascular benefits.

  2. Thanks, as usual, for your information. I am very anxious to see what comes into print about the possible reversal of arterial calcification from the MK-7 study you mention. I know you will see it before me and I would appreciate your sharing it on the board. Your site is much appreciated for the ongoing sharing of knowledge.


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