Introduction

Magnesium is second only to potassium in terms of concentration within the individual cells of the body. The functions of magnesium primarily revolve around its ability to activate many enzymes.

Magnesium deficiency is extremely common in Americans, particularly in the geriatric population and in women during the premenstrual period. Deficiency is often secondary to factors that reduce absorption or increase secretion of magnesium such as: high calcium intake, alcohol, surgery, diuretics, liver disease, kidney disease, and oral contraceptive use.

Signs and symptoms of magnesium deficiency can include fatigue, irritability, weakness, heart disturbances, mental confusion, muscle cramps, loss of appetite, insomnia, and a predisposition to stress.

Magnesium Supplementation in Cardiovascular Disease

Magnesium supplementation has been shown to be an extremely effective therapy or adjunctive measure in many common conditions especially cardiovascular disease. Magnesium is absolutely essential in the proper functioning of the heart. Magnesium's role in preventing heart disease and strokes is generally well-accepted. In addition, there is a substantial body of knowledge demonstrating that magnesium supplementation is effective in treating a wide range of cardiovascular diseases.

For example, magnesium was first shown to be of value in the treatment of cardiac arrhythmias in 1935. More than seventy years later, there are now numerous double-blind studies showing magnesium to be of benefit for many types of arrhythmias including atrial fibrillation, ventricular premature contractions, ventricular tachycardia, and severe ventricular arrhythmias.

Magnesium supplementation has also been shown to be helpful in angina due to either a spasm of the coronary artery or atherosclerosis. The beneficial effects of magnesium in angina relate to its ability improve energy production within the heart; dilate the coronary arteries resulting in improved delivery of oxygen to the heart; reduce peripheral vascular resistance resulting in reduced demand on the heart; inhibit platelets from aggregating and forming blood clots; and improve heart rate.

Magnesium supplementation is also critical in congestive heart failure (CHF). Studies have shown that CHF patients with normal levels of magnesium significantly live longer than those with lower magnesium levels. Many of the conventional drugs for CHF and high blood pressure (diuretics, beta-blockers, calcium channel-blockers, etc.) deplete body magnesium stores. Magnesium supplementation generally produces a modest impact in lowering high blood pressure (i.e., less than 10 mm Hg for both the systolic and diastolic).

Other Conditions Benefited by Magnesium Supplementation

Because of magnesium’s critical role in many body processes, it is not surprising that research has demonstrated magnesium supplementation to benefit many other conditions. For example, since magnesium promotes relaxation of the bronchial smooth muscles, magnesium supplementation is a well-proven and clinically accepted measure to halt an acute asthma attack (via intravenous administration) as well as acute flare-ups of COPD.

Magnesium is known to play a central role in the secretion and action of insulin. Several studies in patients with diabetes or impaired glucose tolerance have shown magnesium to be of significant value. Magnesium supplementation (usually 400 to 500 mg per day) improves insulin response and action, glucose tolerance, and the fluidity of the red blood cell membrane. In addition, magnesium levels are usually low in diabetics and lowest in those with severe retinopathy. Diabetics appear to have higher magnesium requirements.

An underlying magnesium deficiency can result in chronic fatigue and symptoms similar to the chronic fatigue syndrome (CFS). Low red blood cell magnesium levels, a more accurate measure of magnesium status than routine blood analysis, have been found in many patients with chronic fatigue and CFS. Double-blind studies in people with CFS have shown magnesium supplementation significantly improved energy levels, better emotional state, and less pain. Magnesium supplementation has also been shown to produce tremendous improvements in the number and severity of tender points in patients with fibromyalgia.

Magnesium increases the solubility of calcium in the urine. Supplementing magnesium to the diet has demonstrated significant effect in preventing recurrences of kidney stones. However, when used in conjunction with vitamin B6 (pyridoxine) an even greater effect is noted.

Magnesium supplementation is very important in preventing headaches. There is now considerable evidence that low magnesium levels trigger both migraine and tension headaches. In individuals with chronic headaches that have low magnesium levels, magnesium supplementation has been shown to produce excellent results in double-blind studies.

Magnesium needs increase during pregnancy. Magnesium deficiency during pregnancy has been linked to preeclampsia (a serious condition of pregnancy associated with elevations in blood pressure, fluid retention, and loss of protein in the urine), preterm delivery, and fetal growth retardation. In contrast, supplementing the diet of pregnant women with additional oral magnesium has been shown to significantly decrease the incidence of these complications.

Magnesium deficiency has also been suggested as a causative factor in premenstrual syndrome. While magnesium has been shown to be effective on its own, even better results may be achieved by combining it with vitamin B6.

Available Forms:

Magnesium is available in several different forms. Absorption studies indicate that magnesium is easily absorbed orally, especially when it is bound to amino acids, aspartate, citrate, or malate. Inorganic forms of magnesium such as magnesium chloride, oxide, or carbonate are less well absorbed and are more likely to cause diarrhea at higher dosages.

Usual Dosage:

Many nutritional experts feel the ideal intake for magnesium should be based on body weight (6 mg/2.2 pounds body weight). For a 110-pound person the recommendation would be 300 mg, for a 154-pound person 420 mg, and for a 200-pound person 540 mg.

Cautions and Warnings:

If you suffer from a serious kidney disorder or are on hemodialysis, do not take magnesium supplements unless directed to do so by a physician.
People with severe heart disease (such as high-grade atrio-ventricular block) should not take magnesium (or potassium) unless under the direct advice of a physician.

Possible Side Effects:

In general, magnesium is very well tolerated. Magnesium supplementation can sometimes cause a looser stool, particularly magnesium sulfate (Epsom salts), hyroxide, or chloride.

Drug Interactions:

There are many drugs that appear to adversely effect magnesium status. Most notable are many diuretics, insulin, and digitalis.

Nutrient Interactions:

There is extensive interaction between magnesium and calcium, potassium, and other minerals. High dosages of other minerals will reduce the intake of magnesium and vice versa. A high calcium intake and a high intake of dairy foods fortified with vitamin D results in decreased magnesium absorption. Vitamin B6 works together with magnesium in many enzyme systems.

Key References:

• Gums JG. Magnesium in cardiovascular and other disorders. Am J Health Syst Pharm. 2004;61:1569-76.
• Touyz RM. Magnesium in clinical medicine. Front Biosci. 2004;9:1278-93.
• Fox C, Ramsoomair D, Carter C. Magnesium: its proven and potential clinical significance. South Med J. 2001;94(12):1195-201.
• Saris NE, Mervaala E, Karppanen H, Khawaja JA, Lewenstam A. Magnesium. An update on physiological, clinical and analytical aspects. Clin Chim Acta. 2000;294(1-2):1-26.
• Jee SH, Miller ER 3rd, Guallar E, et al. The effect of magnesium supplementation on blood pressure: a meta-analysis of randomized clinical trials. Am J Hypertens. 2002;15:691-6.
• Alter HJ, Koepsell TD, Hilty WM. Intravenous magnesium as an adjuvant in acute bronchospasm: a meta-analysis. Ann Emerg Med. 2000;36(3):191-7.
• Barbagallo M, Dominguez LJ, Galioto A, et al. Role of magnesium in insulin action, diabetes and cardio-metabolic syndrome X. Mol Aspects Med. 2003;24(1-3):39-52.
• Manuel y Keenoy B, Moorkens G, Vertommen J, et al. Magnesium status and parameters of the oxidant-antioxidant balance in patients with chronic fatigue: effects of supplementation with magnesium. J Am Coll Nutr. 2000;19(3):374-82.
• Howard JM, Davies S, Hunnisett A. Magnesium and chronic fatigue syndrome. Lancet 1992;340:426.
• Cox IM, Campbell MJ, Dowson D. Red blood cell magnesium and chronic fatigue syndrome. Lancet 1991;337:757–60.
• Russell IJ, Michalek JE, Flechas JD, Abraham GE. Treatment of fibromyalgia syndrome with Super Malic: a randomized, double blind, placebo controlled, crossover pilot study. J Rheumatol. 1995;22(5):953-8.
• Schwille PO, Schmiedl A, Herrmann U, et al. Magnesium, citrate, magnesium citrate and magnesium-alkali citrate as modulators of calcium oxalate crystallization in urine: observations in patients with recurrent idiopathic calcium urolithiasis. Urol Res. 1999;27(2):117-26.

---

Michael T. Murray, N.D., is widely regarded as one of world's leading authorities on natural medicine. A prolific author, Dr. Murray has written over 20 books on health and nutrition including the best-selling Encyclopedia of Natural Medicine and his latest book The Encyclopedia of Healing Foods. Dr. Murray is also Director of Product Development and Education for Natural Factors one of the leading manufacturers of natural products.