The rda for mag is 400 mg. Some feel better with more (800, 1000, mg etc...) Just go slowly to see how YOU handle mag citrate--even cutting them in half (if they are tablets) at first to make sure you tolerate it. If I take too much at once there are bathroom consequences. (And I NEED it--its not because I have too much mag, but b/c citrate is a hard form for me to take in larger quantities.) If I space it out in 100 mg doses throughout the day I'm *ok* with it. Just have to be careful with it. I think I'm better off using mag oil though for absorption (or perhaps would benefit from the jigsaw kind, etc).