If you're interested, I can post French studies about the difference between magnesium chloride and the other forms of magnesium. My personal experience is that I've been tested magnesium supplements, and the only effective for me, and I guess everybody else who will do the test, is magnesium chloride, far better than the medicines or supplements our doctors give to us, even magnesium + B6 or marine magnesium.
I have also very painful cramps in my calves, caused my a lack of magnesium and/or calcium, the only cure for me is banana and magnesium chloride;