Seems that the richest sources of k2 are from arguably non-paleo food sources -- natto and cheese/butter from grass-fed animals. Since it's not found in appreciable amounts in strictly paleo foods (no soy, no dairy), anybody else wonder if we need to know more about k2 before resorting to dairy and soy foods or supplementing?
K2 IS in paleo foods, but only when eaten the way it was in the past. Our ancestors ate the entire beast. Marrow, organs, blood...nothing was wasted.
Grass fed butter is a good way to approximate these sources vs eating brains or livers.
I'm fully confident that K2 is crucial.
Here's a good, recent article on the topic: http://freetheanimal.com/2011/11/unifying-nutrition-osteoporosis-and-atherosclerosis-may-be-linked-vitamin-k2.html
I supplement daily and feel that I'm on solid scientific ground.
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