Studies have shown a strong correlation between high magnesium intake and lower blood pressure. However, studies using magnesium to treat hypertension (elevated blood pressure) have had mixed results. It seems to work best for hypertensive people who are on diuretics, those with high levels of renin in the bloodstream (causing blood-vessel constriction), or those with high intracellular sodium and low intracellular potassium. Dosages used in the studies ranged from 480-600mg per day. The RDA for magnesium is 300-400mg per day. Optimal intake is 3-6mg per pound of body weight.
You should not take magnesium supplements if you have kidney disease or severe heart disease. Magnesium sulfate, hydroxide or chloride can cause loose stool. The forms that are most easily absorbed and used by the body are aspartate, citrate and malate. Include some vitamin B-6 along with the magnesium, since they work together in the body. If magnesium is going to help with lowering your blood pressure, you should see improvement in a month.
Magnesium is a very important mineral, necessary for hundreds of cellular enzyme reactions, especially those that produce energy. Other conditions that can benefit from magnesium supplementation include elevated cholesterol and triglyceride levels, angina that occurs at rest, asthma, fibromyalgia, tension headaches, osteoporosis, PMS and menstrual cramps.