I've become increasingly interested in vitamin K2, especially since finding out that it is almost surely the elusive "X-factor" discovered by Weston Price in the early 1900's.  Dr. Price suggested that this "X-factor" was one of the most important mineral activators, having a profound influence on calcium metabolism in the body.  He also knew that it was found in the diet mostly in butter from grass-fed cows.  Vitamin K1, on the other hand, is found in leafy green vegetables, and is mostly known for it's role in blood clotting.  Regardless, what role might vitamin K2 have to play in human health?  Well, I found an excellent blog post by a cardiologist discussing in detail the potential benefit of K2 for cardiovascular health.  Here is a particularly useful excerpt from his blog post:

 

Here lies the real interest in high dose vitamin K2 replacement to minimise and reverse vascular calcification as part of general prevention and management of atherosclerotic vascular disease.

This is consistent with separate research also showing superior health benefits from vitamin K2, including:

Source:  http://cardiologydoc.wordpress.com/2013/01/18/vitamin-k2-and-vascular-disease/, (accessed on 8/28/14)

 

Another potential benefit of vitamin K2 may be prostate cancer prevention, as reflected in this study published in the American Journal of Clinical Nutrition.

 

Sources of vitamin K2 in the diet:  Butter (preferably from grass fed cows), soft and hard cheeses, egg yolk, beef (preferably from grass fed cows), natto, among others.

 

Important:  Talk with your doctor before taking vitamin K supplements if you are on blood thinners or have blood clotting concerns.