I do know we will get a low dose of vitamin D3 from one of TEI suppplements..But to take 400 iU right now with very low potassium is not a good idea.. I thought it lowered magnesium too..but I am not sure. Hopefully Onwards can comment on taking D3 and what it lowers.
Also I have been told not to take anything extra in supplements except what is recommeneded...it is a Science behind it..9unless you asked your practititoner and it was ok to).