I've been having a lot of aching and pain in my legs, mostly in the calf region, front and back. We did blood work and it showed my magnesium was low. He started me on 420 MG, but I still had the pain. So after a month we increased it to 840 a month, and its finally at a good level, and most of the time, the pain is gone. Every now and then I do have some pain still, but its usually after a day when I've been on my feet a lot. After the pain had stopped with the increased mag.