This info hits close to home with me. A very good friend who is very alternative in healing and taught me a lot in all the years I've known her...has been thru some drama in the hospital and the dx is arrhythmia aka afib. I don't know how much mag she took, but nothing like the amount I take now for years. Having a lot of recent anxiety seems to have led up to this condition she now deals with. The recent anxiety she tells me felt like a lot of pins and needles thru her body... She is on 4-5 heart meds now and laying real low. So this brings me to thinking, had she been taking optimal mag for her body would she be dealing with this now. ummm Thanks for this good info.