6 Comments
User's avatar
Margaret's avatar

Taking 5 mg/day of MK-4 over several months appears to have negatively impacted my vitamin D status and by symptoms my vitamin E and A status. I regret putting any credence into the falsified studies by those two Japanese researchers.

Expand full comment
Eddie's avatar

I’m fairly certain I accidentally gave myself K2 toxicity. I was taking two 100 mcg of MK-7 per day, once in the morning and once in the evening. I think this was working well for me. It thought it would be more convenient to buy the single 300 mcg capsules and take it once a day. You can probably guess where this is going…

So I started taking these higher dose capsules, but forgetting that they were 300 mcg each, I took them twice a day for a total of 600 mcg per day. Shortly after I was getting all sorts of strange symptoms.

Once I recognized what happened I stopped K. It was 2-3 months after when I began supplementing with vitamin E and NAC. I’ve been slowly but gradually feeling better.

Expand full comment
MA's avatar

Worth to mention that a large number of Japanes studies on vitamin K and osteoporosis (by Yoshihiro Sato and Jun Iwamoto) have been retracted due to "general misconduct, falsification/fabrication of data and results, false/forged authorship, concerns about results and findings, duplications of articles, and unreliable images, data, and findings" (see https://bps.stanford.edu/?page_id=9731)

They have (co-)produced massive amounts of studies, unfortunately now it is difficult to filter out the junk ones :(

Expand full comment
Margaret's avatar

thank you so much for this information! very disturbing. I don't believe the very high dosages they used were safe.

Expand full comment
David's avatar

Wow, this is interesting and so glad I came across it. I (35M) have been dealing with a very slow healing bone stress injury (6 months). Prior to this I was a fit and healthy runner.

For the past 4 months or so I've been taking high dose K2 MK-4 (45mg daily) based on those Japanese studies. Now I'm wondering if this has actually been hindering the healing process because the high levels of K2 are not allowing sufficient bone resorption to take place for the injured bone to be remodelled. I had osteocalcin tested a month ago and it was extremely low.

Chris, I can see you wrote this quite some time ago—are you aware of any new research about optimum doses of MK-4 and MK-7 for bone health?

(This also has me worried that other supplements I am taking to help my bone heal could be doing more harm than good. I'm also taking 600mg calcium, 300mg magnesium, 3g boron, and 2000-3000IU vitamin d.)

Expand full comment
Chris Masterjohn, PhD's avatar

I haven't seen new info that would clarify the dose better than what's here.

Expand full comment