Is magnesium fat or water soluble? is taking too much toxic? how do i know when to stop as tests are not very indicatve right?

Magnesium=necessary: Magnesium is a water soluble mineral that most people are whole-body deficient in. At high doses, it causes diarrhea. If the kidneys are compromised in any way, the dose needs to be lower and monitored by a physician. A RBC magnesium level is the most useful test as serum magnesium is kept at a very steady level. Magnesium is necessary to 300+ reactions in the body.