Jini Says: The type of magnesium you choose largely depends on whether you want to stimulate a bowel movement, or not. Transdermal (through the skin - magnesium oil) does not affect bowel function and neither does the nano-sized magnesium (in both Mini-Minerals Magnesium and Bone Support), since it does not require digestion. The powdered magnesium in Natural Calm and Magnesium Citrate capsules can be used to loosen the bowels at a dosage from 200 - 1000 mg; start low and build up to find your threshold.