I am a Japanese biochemist working in a branch of Japanese pharmaceutical in London.
I have been reading this forum for a while and I'd like to add my knowledge of Vitamin K. However the original thread is locked, I am creating this new thread.
Vitamin K2 MK-4 (menatetrenone or Menaquinone-4) is the choice of treatment of osteoporosis from 50's in Japan. Japanese scientists have discovered that a special protein called osteocalcin binds and transports calcium to where calcium should belong. To put in simply, when osteocalcin sees calcium deposited in a wrong place, such as in heart muscle or artery, it will bind to it and transport it to the bone and depoit it there. However activation of this protein requires Vitamin K2, and they also discovered it is MK-4 form of Vitamin K2 that activates osteocalcin.
It is also discovered that non-MK-4 form of Vitamin K2s do get converted to MK-4 form in body. Animals, including rats are quite efficient in the conversion but many people show deficiency in the conversion and these people develop osteoporosis.
What is interesting in Vitamin K2 MK-4 treatment is that, no calcium supplement is given but the bone still strengthens. This is because our body already have more than enough calcium to make our bone strong, but the calcium is in wrong place and once osteocalcin is activated, it moves calciums that are already in our body to the place they should belong.
All studies were done using MK-4 form of Vitamin K2, because when animals are sacrificed after having fed with diets rich in Vitamin K1 and Vitamin K2 MK-7 but devoid of Vitamin MK-4, still predominant the form of Vitamin K found in their body is MK-4. The consensus is that, MK-4 is the only usable form of Vitamin K2 in our body and other forms of vitamin K2s remain unused till they are converted to MK-4. The problem compounds at this point, because all Vitamin K2s coagulate blood and unless immediately utilised, Vitamin K2 circulating in blood plazma in substantial quantity poses serious hypercoagulation risks. Interestingly, people prone to osteoporosis are also prone to atherosclerosis, which can be easily understood in this context, in that, non-MK-4 form of Vitamin K2s stay much longer in the blood plasma in conversion deficient people, which in turn, act as hypercoagulation agent, in other words, may trigger formation of atherosclerosis and eventualy ischemic stroke. This is why non-MK-4 form of Vitamin K2 is never used for any kind of treatment except hypo-coagulation symptom and this is also why in Japan, Menaquinone or Menaquinone-7 (MK-7) are only allowed to be sold in mcg strength by law, never in mg(miligram) strength (similar law exists here in the UK). MK-4 is prescribed upto 90mg(miligram) a day, but MK-7 should never be ingested in miligram strength. Doing so will put you in risk of ischemic stroke.
It should be also noted that current push of MK-7 by many supplement manufacturers originated from sudden surge of demand of Nattokinase all over the worlds. Nattokinase is produced by removing Vitamin K from Natto, and the form of Vitamin K in Natoo is MK-7. This left Nattokinase manufacturers surplus of MK-7, thus they are pushing MK-7 as an osteoporosis cure. You can easily see this by comparing Nattokinase venders and MK-7 venders. They are the same.
I hope this havs clarified some of the confusion raised in this forum regarding MK-4.
PS: Natto as food, does not pose hypercoagulation risks because it is well balanced between MK-7, a clot forming factor and Nattokinase, fibrinolytic factor.
Edited by asako, 30 March 2010 - 06:01 AM.