In addition to its functions as an electrolyte, chloride combines with hydrogen in the stomach to make hydrochloric acid, a powerful digestive enzyme that is responsible for the breakdown of proteins, absorption of other metallic minerals, and activation of intrinsic factor, which in turn absorbs vitamin B12.
As human organism gets older it cannot produce enough hydrochloric acid due to magnesium deficiency. Thus, we cannot absorb magnesium oxide or magnesium carbonate in the right amount.
Therefore, a vicious circle is created. Magnesium seems to be entering the human body, when experiencing its deficiency, but because of the magnesium self-deficiency, human body cannot absorb it