I've had IBS-"C" for many years. Even during the years I wasn't LCing I took magnesium to keep things moving. I also have fibromyalgia, and malic acid(magnesium malate)is the form a 'fibro doc' recommended to me years ago, so that is the form I still take. I don't recall the affect it was supposed to have on the fibro(maybe a muscle relaxant), but it definitely helped the "C", so I've stuck with it.