Also, Chris Masterjohn is doing (and has some) some kick but pioneering research on the NEED to do K2, D, and A (not beta carotne) TOGETHER. It's what he wrote his thesis on and continues to write/research about it. D CAN be toxic, but take it with the A and K (10:1 A:D - 4:1 A:D are the estimated best ranges)
Also, Sodium Tetraborate (borax) is just a hydrated sodium-boron salt. Nothing scary or bad about it. I'm sure tri-boron could just as easily be used as ant-killer if that's what you're concerned about. That's why it's lethal dose is the same as regular salt.