mk-4 is the preferred form by our body. mk-4 and mk-7 have been studied in korea and japan for decades (koreans too, consume natto-equivalent traditional food that is also rich in mk-7) and study after study, mk-4 shows superior efficacy. this is why no illness or condition is treated by mk-7 in korea and japan. note that mk-7 is only recently being pushed by studies paid for by nattokinase manufacturers. why? mk-7 is a byproduct of nattokinase (nattokinase is basically mk-7 removed natto) and as nattokinase gains huge popularity in the US, which btw is a ludicrous trend since nattokinase can be very very dangerous, nattokinase manufacturers now are trying to catch two rabbits with one stone: clearing their huge surplus of mk-7 and profiting doing so.
also note that k1, mk-4 and mk-7 all will shorten thrombin time (thicken blood), which means longer plasma half-life will raise possibility of ischemic stroke i.e. mk-7 is undesirable in this regard also (mk-4's short plasma half life is due to its superior availability, not because it is excreted fast)
What studies are you talking about? Sources please.
Look at the studies in this thread. Many were mk7 beats the others epidemiologically (although these are limited to the amounts food in normal diets). K1 has, for example, a very interesting, placebo-controlled, four year long, but rather small, study, were fractures, cancer, and general serious disease were greatly reduced. Mk4 regarding prevention only has several Japanese osteoporosis and fracture studies using very high amounts.
The claims regarding ischemic stroke is false. Unless you have a source. For example the K1 study found no such an effect. All the Ks are necessary for proper functioning of certain clotting proteins but once that is done they have no further effect regarding this.
Also a source please for the claim regarding inefficient conversion.
Edited by Blue, 24 March 2010 - 07:12 PM.