I regularly take magnesium and calcium but still once in a while I got muscle cramps. This Potassium citrate is so great that as soon as I take a tablet, the cramps are gone. I never take anything for too long, it feels better. Also I learned that magnesium & calcium are absorbed by the same receptors in the guts. But they only can absorb either one at a time. Therefore It is wise to take calcium in the morning and magnesium in the afternoon.