Vitamin K2 helps with smooth muscle histamine reactions, thus it's a viable choice for people who's gut-food histamine response triggers a whole body histamine reaction. The G.I. tract, arteries, bladder, respiratory tract, some skin cells, and eyes have smooth muscle components. So if you aren’t already taking Vitamin D3 with K2, we’d suggest you add it to your regimen. Here is a link to one such recommended product: http://www.gutthrivein5.com/Vitamin-K2-with-D3