Magnesium supplements, Therapeutic uses of supplements

Cardiovascular disease

Heart attack

Low magnesium levels have been found in the blood and cardiac muscle of heart attack victims, and several small studies have shown that magnesium sulfate injections can reduce death rates in heart attack patients, both in the short term and for longer periods. It may act by improving energy production, inhibiting platelet aggregation, reducing vascular resistance, promoting clot breakdown, dilating blood vessels, and improving the function of heart muscle. It also protects the damaged heart muscle against calcium overload and reduces free radical damage.

Magnesium supplementsHowever, two recently published studies showed different results, although similar doses of magnesium were used. The LIMIT-2-study was a double- blind, placebo-controlled investigation of over 2300 patients with suspected heart attack. Magnesium infusion reduced 28 day death risk by 24 per cent. The ISIS-4-study on over 50,000 patients with suspected heart attack did not show any positive effect of magnesium on death rate.

However, in the ISIS-4 study, magnesium supplements were given after the end of drug therapy to break down blood clots. In LEVHT-2, magnesium infusion was started as early as possible. It seems that in heart attack patients who have been given clot break-down drugs, magnesium therapy is not useful. These studies also suggest that timing of the magnesium treatment is important, and evidence suggests that the injections should be given early. Magnesium injections also show more beneficial effects in higher risk patients.

Cardiac arrhythmias

Magnesium is reasonably well-established as a therapy for certain types of cardiac arrhythmia. It is usually given intravenously. Post-operative administration can also reduce the incidence of arrhythmias following surgery. Magnesium may also enhance the action of digoxin, a drug often used to treat cardiac arrhythmia.


Magnesium supplements are often used to treat angina, both that caused by atherosclerosis and variant angina caused by coronary artery spasm. In a 1997 study, UK researchers assessed the effects of a 24-hour infusion of magnesium in patients with unstable angina. Thirty-one patients received magnesium sulfate and 31 placebo. After treatment, there were fewer ischemic episodes in the magnesium group, and duration of ischemia in the placebo group was longer than that in the magnesium group.

Other heart conditions

Magnesium has also been used to treat cardiomyopathy, a weakening of heart muscle which leads to reduced efficiency of blood circulation and congestive heart failure. Sufferers of intermittent claudication, a painful condition caused by reduced blood flow to the legs, often have low magnesium levels and may be helped by supplements. Magnesium supplements have been successfully used to treat mitral valve prolapse. Magnesium supplements have been shown to reduce cholesterol and triglyceride levels.

Magnesium supplementsHigh blood pressure

Magnesium supplements may be useful in the treatment of high blood pressure, although the results of studies have been mixed. Intravenous magnesium has been shown to reduce blood pressure, possibly by relaxing constricted blood vessels. Those with high sodium and low potassium levels and those taking diuretic drugs may benefit from magnesium supplements.

In a 1997 double-blind, placebo-controlled study carried out in Japan, 33 people received either a four-week treatment with oral magnesium supplementation (411 to 548 mg per day) or a placebo. The results showed that the systolic and diastolic blood pressure values decreased significantly in the magnesium group, but not in the placebo group. Measurements made during the study suggest that magnesium may lower blood pressure through its effects on the secretion of adrenal hormones which cause an increase in sodium excretion.

In a 1994 study, 91 middle-aged and elderly women with mild to moderate hypertension who were not on antihypertensive medication were treated with either magnesium supplements or placebo for six months. At the end of the study, systolic blood pressure had fallen by 2.7 mm Hg and diastolic blood pressure by 3.4 mm Hg more in the magnesium group than in the placebo group.

Kidney stones

Magnesium supplements may be helpful in the treatment of kidney stones. In a 1997 study, researchers examined the use of potassium-magnesium citrate in the prevention of recurrent calcium oxalate kidney stones. Sixty-four patients received either a placebo or potassium-magnesium citrate daily for up to three years. The results showed that those in the supplement group had an 85 per cent lower risk of recurrence of stones. Mineral water containing high levels of calcium and magnesium may also be useful in preventing the formation of calcium oxalate kidney stones.


Magnesium sulfate is routinely used in the USA to prevent convulsions in pre- eclampsia and to break down toxins in pre-term labor. A 1996 research review of trials of magnesium sulfate in the treatment of eclampsia and pre-eclampsia analyzed data from nine randomized trials involving 1743 women witheclampsia and 2390 with pre-eclampsia. The analysis showed that magnesium sulfate is effective in preventing the recurrence of seizures in eclampsia and in pre- venting them in pre-eclampsia.

Researchers involved in a 1996 study reported in the Journal of the American Medical Association found that administration of magnesium sulfate to women before delivery reduced the risk of cerebral palsy in very low birthweight babies.

A 1995 Swedish study showed that magnesium supplements may help reduce the pain and discomfort of night-time leg cramps that up to one-third of pregnant women suffer. Pregnant women tend to have lower blood magnesium levels than those who are not pregnant.

Magnesium supplementsDiabetes

Diabetics can benefit from magnesium supplements as they have been shown to improve glucose tolerance and insulin response and action. Magnesium may help protect against diabetic complications including heart disease and eye disorders.

In a 1994 study, Italian researchers investigated the effects of magnesium supplements on glucose uptake and use in nine elderly Type II diabetic patients. Each patient was followed up for a period of three weeks before the study and was then given either a placebo or a magnesium supplement for four weeks. At the end of this time, improvements in insulin sensitivity and glucose oxidation were seen in those taking magnesium. Magnesium supplements have also been shown to lower blood pressure in Type II diabetics.


Magnesium can act as a bronchial smooth muscle relaxant, and its use in the treatment of asthma is still in investigational stages. In a 1997 randomized, double-blind, placebo-controlled, cross-over study, 17 asthmatic people were given a low magnesium diet for two periods of three weeks, preceded and separated by a one week run-in/wash-out, in which they took either placebo or 400 mg magnesium per day. Asthma symptom scores were significantly lower during the magnesium treatment period. Intravenous magnesium has been successfully used as an emergency treatment for asthma in children. Magnesium sulfate aerosol has also been used effectively.


Magnesium supplements may be beneficial in the treatment and prevention of migraine. In a 1996 study, Belgian researchers assessed the effect of oral magnesium on the prevention of migraine in 81 patients aged from 18 to 65. They were either given a placebo or a daily supplement of 600 mg for 12 weeks. In weeks nine to 12, the attack-frequency was reduced by 42 per cent in the magnesium group and by 16 per cent in the placebo group. The number of days with migraine and the drug consumption for symptomatic treatment per patient also decreased significantly in the magnesium group. Magnesium supplements may also be useful in the treatment of menstrual migraine.

Premenstrual syndrome

Magnesium supplements treatment has been shown to relieve menstrual and premenstrual symptoms including mood changes and breast tenderness. In a 1991 study, Italian researchers investigated the effects of a two-month period of magnesium supplementation on premenstrual symptoms in 32 women. The dose used was 360 mg three times a day, from the 15th day of the menstrual cycle to the onset of menstrual flow. The results showed that supplementation was effective in the treatment of premenstrual symptoms related to mood changes.

Chronic fatigue syndrome

Magnesium sulfate injections have been shown to improve the symptoms of chronic fatigue syndrome. Further research is need to determine if oral supplements can show the same effects.


Magnesium supplements may help to increase bone mineral density in postmenopausal women, thus reducing the risk of osteoporosis. In a 1990 study, US researchers investigated the effect of a dietary program emphasizing magnesium instead of calcium for the management of postmenopausal osteoporosis. Nineteen women on hormonal replacement therapy (HRT) received 500 mg magnesium and 600 mg calcium, and seven other women on HRT did not receive supplements. The results showed that in one year, those women given the supplements had greater increases in bone mineral density than those who were not. Fifteen of the 19 women had had bone mineral density below the spine fracture threshold before treatment; within one year, only seven of them still had values below that threshold.

In a 1993 study, Israeli researchers assessed the effects of magnesium supplements in 31 postmenopausal women who received six 125 mg tablets daily for six months and two tablets for another 18 months in a two-year trial. Twenty-three symptom-free postmenopausal women were assessed as controls. The results showed that 22 patients responded with a 1 to 8 per cent rise of bone density. The mean bone density of all treated patients increased significantly after one year and remained unchanged after two years. In control patients, the mean bone density decreased significantly.

Other uses

Supplements have also been used in the treatment of epilepsy, glaucoma, attention deficit hyperactivity disorder (ADHD), hearing loss, thalassemia, irritable bowel disorders and alcoholism. Taken with calcium they may have neuromuscular relaxing effects and may be useful in insomnia. Some antacids contain magnesium bound to an alkali that neutralizes stomach acid. It is also used as a laxative (in milk of magnesia) as it draws fluid into the bowel.

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