There has been some buzz about it recently. However, it is often recommended to take the MK7 form and advised against buying MK4. I will simply present selected research on both.
Osteoporosis and bone strengthening
In a recently published study, MK7 taken for 3 years at 180 mcg / day prevented osteoporosis of the spine in postmenopausal women, but had no effect on other bone health.
In another, a form of MK7 had no effect on the bone health of postmenopausal women, taken at a dose of 360 mcg for 1 year.
This was confirmed in another study, where a dose of 360 mcg for one year was also used. In both, there were some positive effects, such as a change in blood concentrations of certain metabolites, but bone health itself did not improve.
When given at a very high dose of 45 mg together with vitamin D2, it reduced fractures by seven times (!) compared to placebo, very strongly increasing bone density. (edit – well yes, it was too good to be true, years later it turned out that the results were at least colored, and possibly completely made up)
A dose of 1.5 mg per day was enough for a form of MK4 to stop bone density loss in elderly women.
45 mg per day significantly increased bone strength.
As you can see, the MK4 form seems to have a much stronger effect – MK7 usually didn’t work at all, or if it did, it had little effect.
As it turns out, the K1 form also increased bone density.
Three years of 180 mcg daily doses reduced arterial stiffness slightly, but mostly in women who had very large lesions.
There is another one on rats which is not relevant at all because it “treated” a specific form of calcification caused by… vitamin K deficiency, such a thing does not occur outside the laboratory. Nevertheless, this study was publicized and used to boost MK7 sales.
One year of supplementation with a dose of 45 mg daily had no effect in terms of calcification prevention, although there were improvements in other parameters in some patients. Overall, the effect was very similar to that for MK7.
Finally, a surprise: ordinary vitamin K, the most common one costing a penny, in a clinical trial prevented the formation of calcifications in the cardiovascular system.
Bottom line – it looks like vitamin K2 is a storm in a teacup. Both MK4, MK7 and regular K1 have some effect on disease risk, but it is small. Very good results have come out of epidemiological studies where they looked at how much of these vitamins were consumed by whom in the diet, but this type of analysis is of very little value, as necessarily people who ate K2-rich foods had a generally different diet than those who did not.
The strongest effect was observed for liver cancer. People with viral inflammation of this organ have a very high risk of developing cancer, on the order of tens of percent. Supplementation in both clinical trials (1) (2) reduced this risk by several times. Not to be too rosy – supplementation did not prevent recurrence of the disease after it was cured.
There are many studies that suggest that K2 may have a clear effect of not only preventing but even curing cancer, but these are just suggestions – thousands of things in a test tube have already “cured” cancer.
Again, a surprise – simple vitamin K1 prevented cancer, in one clinical trial reducing its risk by several times – but it must be fair to say that the number of patients there was too small, it could have been a coincidence.
There is a lot of buzz about K2, but I would remain cautious for now. Very few studies show the effectiveness of the MK7 form, only two to be exact. There are a great many clinical trials where the MK4 form has shown quite strong effects. However, if we compare it not to a placebo, but to vitamin K1, the simplest one – the difference is no longer so great.
The MK7 form was advertised on the basis of one single rat study and the twisted logic of “since it stays in the blood longer, it’s better!” (while ignoring the fact that it does NOT stay longer in the blood in rats). Maybe it stay in because our cells are unable to assimilate it? However, it is the human clinical trials that are behind the MK4 form. Truth be told, studies show that regular K1 has even stronger effect than MK7.
If I had to choose, I would buy a supplement that contains MK4 first, followed by K1, only lastly MK7. If you look carefully, there are products available that contain all three forms – but I wouldn’t want to advertise a particular retailer or manufacturer. However, I would not count on any particularly great effects of supplementation. Very high hopes can be placed on its role in cancer prevention, but here research is in its infancy and it is not yet known what will emerge from it.