Can children take a magnesium supplement without having a deficiency confirmed by testing? Absolutely yes! Magnesium is the master mineral; it’s vital for hundreds of functions in the body; we need it to build strong teeth and bones, heart health, blood pressure, energy production, DNA repair, tissue repair, muscle function, blood sugar regulation, nervous system regulation, and so many more. I can’t tell you how important it is. We don’t want to get to the stage where our children are showing s