depletes? you were already deficient in magnesium.
the correct picture is more likely your body was so bereft of Iodine that when supplemented, processes in the body started working again and used up your meager stores of the magnesium from your deficient diet.
doesnt that sound more like it?
iodine is a mobilizer of metals and an unobstructor to detox pathways. it only gets rid of what you dont need, like distilled water does. no de-mineralization of your body's cells occurs.