I've actually been wondering how safe it is to take large doses of Mg. Since it's a mineral I think large quantities can cause imbalances of electrolytes in our system. I remember reading a while ago that taking Mg supplements over a long period of time can lead to kidney failure. But I'm not sure how many mg of Mg did they refer to. We the people who suffer from IBS-C take a lot of Mg - either as a supplement or in MOM. I wonder if it's safer to take vitamin C instead since it's water soluble and thus gets flushed out of our system. Does anybody know more about risks associated with Mg supplements?