For those that don't get on with tablets (I am ok with them) you can buy magnesium powder as well
My fear was getting the trots but the first thing I told someone in a health food shop was about my meno headaches and she went straight to Magnesium...
Types and their uses:
Magnesium Citrate - mild laxative, best for constipation
Taurate - best for cardiovascular health
Malate - best for fatigue
Glycinate - most bioavailable, non laxative
Chloride - for detox
Carbonate - antacid/reflux
Probably best to test your tolerance before you max out to 400g a day