My current clients know that I love to preach about the benefits of magnesium supplementation. Magnesium plays a role in bone health, immunity, muscle, nerve, heart function and metabolism. There is new research suggesting that magnesium may also be helpful in managing diabetes, hypertension and cardiovascular disease. I recently discovered that magnesium and vitamin K play a role in preventing the calcification of arteries. When inadequate levels of vitamin K are present, blood calcium, which is tightly regulated by the body, may deposit itself in arteries, leading to heart issues including heart attack and stroke. High levels of magnesium intake have been associated with lower levels of diabetes, metabolic syndrome and C-Reactive protein (an inflammatory marker which suggests risk of heart complications).
        I have Raynauds Syndrome, a condition where blood flow to the extremities is limited, causing pain and numbness, and sometimes complications. While I am very healthy, it is an annoying and painful issue during the cold, and even during the rain today, I lost sensation in one finger. My doctors suggested a script for a calcium channel blocker, which is a pharmaceutical with serious side effects and a cost of at least $20 a month.  I asked about other supplements for this issue including arginine and alpha lipoic acid and hot yoga. The suggestion was to stick to the pharma. Then I open my Life Extension and realize that magnesium is a natural calcium channel blocker!The relaxing of the arteries can reduced migraines as well.
          Some research has demonstrated that magnesium helps to maintain plasticity in the brain synapses.Unlike calcium, magnesium will act as a natural laxative. It should be introduced slowly.
Check with your doctor before starting any supplements. Most people should be fine with 500mg a day. Magnesium orotate, glycinate, and threonate are good choices.
http://www.lef.org/magazine/mag2005/sep2005_awsi_01.htm
http://www.lef.org/magazine/mag2008/may2008_Magnesium-Widespread-Deficiency-With-Deadly-Consequences_01.htm?source=search&key=magnesium