As I understand there are magnesium and magnesium but which is the right one?
My theory is that if one takes larger quantity of wrong type of magnesium (in wrong form) the net result is that body looses some good BIOAVAILABLE magnesium.
If large amount of wrong form of magnesium enters the body, it will be rejected by kidneys therefore depleting useful minerals out of your body, including bioavailable magnesium.
The best source of that would be natural like nuts, grapefruit, apples and dark green vegetables.
I can't answer your question about magnesium choride.