K1 comes from veggies. K2 is almost exclusively from animal products (except for natto, yum!).
Apparently our bodies can synthesize some K2 from K1 but my understanding is that's quite variable and should not assumed to be adequate.
There's a fair amount of research linking arteriosclerosis to a deficiency of K2, so it's part of my supplement regimentation. It's definitely worth researching if you're interested in optimizing your health in a very lazy manner :-).
It turns out the research for that doesn't meet evidence-based medicine standards. Almost all observational studies of human nutrition are junk science with small effect sizes and poor controls.
the evidence for that was mostly based on Ancel Keys' work around the 1950s and it has been pretty clearly shown that he cherry picked the data in his observational study. When analyzed properly, the link between any kind of heart disease and red meat disappears. Look up Gary Taubes work for thorough references
As I gather, we still believe that red meat consumption leads to heart disease, but we're becoming less sure of his hypothesis that the elevated cholesterol resulting from saturated fat (found in red meat) causes heart disease.
There is an assumption here that there is one diet is the best in all respects. But I don't think that's the case. Diets have benefits and drawbacks. Like over the years we have adapted a little bit in this direction and then later a little bit in that direction and that's how we are where we are.
Apparently our bodies can synthesize some K2 from K1 but my understanding is that's quite variable and should not assumed to be adequate.
There's a fair amount of research linking arteriosclerosis to a deficiency of K2, so it's part of my supplement regimentation. It's definitely worth researching if you're interested in optimizing your health in a very lazy manner :-).