30 mg is the highest you should take. DO NOT GET OXIDE, same goes for Magnesium Oxide unless you want diarrhea. Use Citrate.
My magnesium and D are normally prescription. Sometimes potassium as well.
I recently got Zinc gluconate 50 mg and have been cutting them in 1/2. I may cut in thirds from here on out tho. Being an (remission) acute leukemia patient, I can’t be messing with my blood too much.