Here you can find all info you want: https://examine.com/supplements/vitamin-k/

Search on that page for: "Skeleton and Bone Metabolism". K1 and K2 work differently. We know a lot but there is still a lot more we don't know. Hell, looks like even different versions of K2 (from MK-4 to MK-13) works for different stuff in body. Only because MK-7 stays in blood for longer than MK-4 doesn't mean that it better. It could also mean that body is better in utilizing MK-4, or even that it's using it for different stuff.

More here: https://chrismasterjohnphd.com/2016/12/03/start-here-for-vit...

Both of those sites appear to be money-making ventures that sell vitamins; I wouldn't consider them reliable sources.

Here is a university page with information:

http://www.umm.edu/health/medical/altmed/supplement/vitamin-...

Examine.com does NOT sell vitamins/supplements.

They collect and analyze available research, and the result of that process is their product (in the form of guides etc).

Thanks for noting this. Their web site design (as well as the use of a dotcom domain) gives a misleading impression

And Chris Masterjohn, PhD is also working with them, example http://v6.examinecdn.com/erd/chrismasterjohn2.pdf

Personally I don't know better source with information about different supplements than examine.com, more how they are working here: https://examine.com/about/ If you know better source point it to me, please. This university page you provided is short and old.

Just one question: what's wrong with using dotcom domain?

If examine.com's metaanalsyses are based on legitimate research papers -- and you've read some of the papers yourself and find that they indeed provide support for the article citing them -- then i'd say yeah, use the site.

i guess to respond to your question: most biomedical research today is eminating from universities and university-affiliated entites. page for page, i generally wouldn't expect a .com web site -- the majority of which are probably just attempting to generate advertising revenue -- to be on par in terms of accuracy etc with a .edu site. generally, I've found one of the best ways to improve the signal-to-noise ratio is to filter to a specific set of domains (e.g., ,edu, .gov) when searching online.

Indeed we don't, plus the two forms of vitamin K (phylloquinone and menaquinone) have different mode of action.

They are important cofactor for many proteins, including one called osteocalcin, needed for bone calcification.

It looks like Vitamin K also inhibits arterial calcification.[1]

1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4052396/

Correct; see my other comment as well. Vitamin K supplementation should not be casually added to anyone's diet without careful evaluation.