Magnesium

Overview

Magnesium is a cofactor in over 300 enzymatic reactions in the body. It is necessary for the transmission of nerve impulses, muscular activity, temperature regulation, detoxification reactions, and for the formation of healthy bones and teeth. It is involved in energy production and the synthesis of DNA and RNA.

A U.S. Department of Agriculture survey revealed that approximately 75 percent of Americans do not ingest the RDA of magnesium. Sub-optimal magnesium intake compromises cellular activity, especially in tissues of the heart, nerves, and kidneys.

Magnesium influences many of the activities associated with a wide variety of cardiac medications. For example, magnesium inhibits platelet aggregation, thins the blood, blocks calcium uptake (like calcium channel blocking drugs), and relaxes blood vessels (like ACE inhibitors). Magnesium also increases oxygenation of the heart muscle by improving cardiac contractility.

Dosage Info

Dosage Range

Generally 400-1500mg a day. Depending on the dosage form and the magnesium salt used, doses as high as 5 to 6 grams have been used under intense medial supervision. (1) , (2)

Most Common Dosage

400mg daily.

Magnesium carbonate contains 40-43.5% Magnesium oxide and Magnesium trisilicate powder contains >20% Magnesium oxide

Dosage Forms

Tablets, capsules, powder, sprays, liquids, and injectables (Rx only).

Adult RDI

400mg

Adult ODA

400-600mg

RDA

• Infants < 6 months: 30mg (Adequate Intake, AI)
• Infants 7-12 months: 75mg (AI)
• Children 1-3 years: 80mg
• Children 4-8 years: 130mg
• Children 9-13 years: 240mg
• Males 14-18 years: 410mg
• Females 14-18 years: 360mg
• Males 19-30 years: 400mg
• Females 19-30 years: 310mg
• Males >31 years: 420mg
• Females >31 years: 320mg
• Pregnancy 31 years: 360mg
• Lactation 31 years: 320mg

Interactions and Depletions

Interactions

• penacillamine
• Tetracyclines
• calcium
• phosphate

Depletions

• Aminoglycosides
• amphotericin B
• cholestyramine
• Corticosteroid medications
• Hormone replacement therapy (HRT)
• foscarnet
• digoxin
• Loop diuretics
• Oral contraceptives
• pentamidine
• Thiazide diuretics

Active Forms

Magnesium oxide, hydroxide, gluconate, glycinate, sulfate, chloride, aspartate, malate, succinate, fumarate, ascorbate, and citrate.

Absorption

Magnesium is absorbed primarily from the jejunum and ileum sections of the small intestine via two mechanisms. One is a carrier-mediated process that operates when magnesium levels are low. The other mechanism is a simple diffusion process that occurs when magnesium levels are higher.

Toxicities & Precautions

General

Kidney excretion of excess magnesium prevents magnesium toxicity.

Side Effects

Excess intake of inorganic magnesium salts cause diarrhea.

Functions in the Body

Metabolism:

Required for the metabolism of carbohydrates, proteins and fats, as well as activity related to calcium, phosphorus, and vitamin C. It is vital for the health of nervous and muscular tissues throughout the body.

Enzyme Activity:

A cofactor for oxidative phosphorylation in the production of ATP. Essential for the production and transfer of energy for protein and lipid synthesis, contractility of muscle, and nerve transmission.

Heart Disease:

Adequate magnesium intake reduces the risk of cardiovascular disease and increases the rate of survival following a heart attack. If intravenous magnesium is given during the early stages of a heart attack, it results in a 70 percent decrease in deaths within one month following the event.

Cardiovascular Function:

Magnesium influences many aspects of cardiovascular health. It decreases platelet stickiness, helps thin the blood, blocks calcium uptake, and relaxes blood vessels.

Blood Pressure:

Can lower elevated blood pressure. However, the effect is usually only moderate, and thus magnesium should not be viewed as a primary treatment for hypertension.

Bone:

Involved in calcium metabolism, the synthesis of vitamin D, and the integrity of skeletal bone-crystal formation.

Teeth:

Magnesium helps to bind calcium to tooth enamel, thus creating a barrier to tooth decay.

Clinical Applications

Congestive Heart Failure

Patients with inadequate magnesium levels have lower survival rates than those with normal magnesium levels. (3) , (4)

High Blood Pressure

Magnesium has a slight blood pressure lowering effect, especially in magnesium-depleted patients. (5) , (6)

Migraine Headaches

Patients with migraines have low brain magnesium levels (7) and in a study of 3,000 women, 80 percent responded well to magnesium supplementation. (8) , (9)

Muscle Cramps

Muscle cramps, especially during pregnancy, respond well to magnesium supplementation. (10) , (11)

Fatigue

Magnesium is necessary for the synthesis of ATP and it facilitates the transport of potassium into cells. A deficiency of magnesium or potassium can result in fatigue. Magnesium provides improvement for many chronic fatigue patients. (12)

Mitral Valve Prolapse

Magnesium deficiency is found in about 85 percent of MVP cases and magnesium successfully relieves symptoms in most cases. (13) , (14)

Asthma

Various studies report low magnesium levels in asthma patients. Consuming adequate magnesium may reduce the risk of developing asthma and is frequently useful as part of an overall treatment program. Magnesium sulfate produces smooth muscle relaxation. (15)

Diabetes

Magnesium is involved in glucose metabolism and insulin secretion. Hypomagnesemia occurs in approximately 25 percent of patients with diabetes. Low levels of magnesium have been reported in childhood Type 1 diabetes and in adults with Type 1 or Type 2 diabetes. (16)

Kidney Stones

Low magnesium increases the risk of calcium oxalate stones and supplementation lowers risk and rate of stone formation. (17)

Osteoporosis

Magnesium is necessary for bone formation and magnesium deficiency is frequently found in patients with osteoporosis. (18) , (19)

Cardiovascular Disease

Magnesium works like many cardiac drugs; it inhibits platelet aggregation, helps thin the blood, blocks calcium uptake, and relaxes blood vessels. (20) , (21)

PMS

Numerous studies report that women with premenstrual syndrome have low levels of magnesium, and some studies report that magnesium helps to relieve PMS symptoms. Magnesium supplementation significantly improved mood plus women’s overall scores on the Menstrual Distress Questionnaire. (22)

Symptoms and Causes of Deficiency

Although clinical deficiency is rare in the U.S., marginal deficiency appears to be widespread with various studies reporting that approximately 75 percent of Americans ingest less than the RDA. Deficiency symptoms include: muscle cramps, weakness, insomnia, loss of appetite, GI disorders, kidney stones, osteoporosis, nervousness, restlessness, irritability, fear, anxiety, confusion, depression, fatigue, and high blood pressure.

It is now known that many heart attacks occur in people with healthy hearts. Magnesium deficiency increases calcium/magnesium ratio, which can cause a cardiac muscle spasm resulting in a heart attack, and frequently, death. Magnesium is important for prevention of cardiovascular disease. Magnesium deficiency is associated with increased incidence of atherosclerosis, hypertension, stroke, and heart attacks. Low levels of magnesium can cause stiffness in the vasculature, which elevates blood pressure and can cause a contraction or spasm in the heart muscle, which can result in sudden death.

Dietary Sources

The magnesium content in foods varies widely, as does the soil content of magnesium. Good food sources include nuts, legumes, cereal grains, and dark green leafy vegetables.

Food processing is a major cause of magnesium depletion. For example, up to 85 percent of magnesium is lost when whole wheat is refined to produce white flour. Modern farming techniques contribute to increasing soil depletion of magnesium. Artificial fertilizers used by farmers usually do not contain any magnesium. Poor food choices, excess calcium intake, intestinal malabsorption, alcohol abuse, liver and kidney disease, and diabetes can also cause deficiencies.

References

1. View Abstract: Brewer RP, Parra A, Lynch J, Chilukuri V, Borel CO. Cerebral blood flow velocity response to magnesium sulfate in patients after subarachnoid hemorrhage. J Neurosurg Anesthesiol. Jul2001;13(3):202-206.
2. View Abstract: Harnett MJ, Datta S, Bhavani-Shankar K. The effect of magnesium on coagulation in parturients with preeclampsia. Anesth Analg. May2001;92(5):1257-1260.
3. View Abstract: Gottlieb SS, et al. Prognostic Importance of the Serum Magnesium Concentration in Patients with Congestive Heart Failure. J Am Coll Cardiol. Oct1990;16(4):827-31.
4. View Abstract: Al-Delaimy WK, Rimm EB, Willett WC, Stampfer MJ, Hu FB. Magnesium intake and risk of coronary heart disease among men. J Am Coll Nutr. Feb2004;23(1):63-70.
5. View Abstract: Moore TJ. The Role of Dietary Electrolytes in Hypertension. J Am Coll Nutr. 1989;8(Suppl):68S-80S.
6. View Abstract: Kh R, et al. Effect of oral magnesium supplementation on blood pressure, platelet aggregation and calcium handling in deoxycorticosterone acetate induced hypertension in rats. J Hypertens. Jul2000;18(7):919-26.
7. View Abstract: Ramadan NM, et al. Low Brain Magnesium in Migraine. Headache. Oct1989;29(9):590-93.
8. Weaver K. Magnesium and Its Role in Vascular Reactivity and Coagulation. Contemp Nutr. 1987;12(3):1.
9. View Abstract: Mauskop A, et al. Role of magnesium in the pathogenesis and treatment of migraines. Clin Neurosci. 1998;5(1):24-7.
10. View Abstract: Riss P, et al. Clinical Aspects and Treatment of Calf Muscle Cramps During Pregnancy. Geburtshilfe Frauenheilkd. May1983;43(5):329-31.
11. View Abstract: Dahle LO, et al. The effect of oral magnesium substitution on pregnancy-induced leg cramps. Am J Perinatol. Jan1997;14(1):55-7.
12. View Abstract: Cox IM, et al. Red Blood Cell Magnesium and Chronic Fatigue Syndrome. Lancet. Mar1991;337(8744):757-60.
13. View Abstract: Galland LD, et al. Magnesium Deficiency in the Pathogenesis of Mitral Valve Prolapse. Magnesium. 1986;5(3-4):165-74.
14. View Abstract: Lichodziejewska B, et al. Clinical symptoms of mitral valve prolapse are related to hypomagnesemia and attenuated by magnesium supplementation. Am J Cardiol. Mar1997;79(6):768-72.
15. View Abstract: Skotnicki AB, et al. The Role of Magnesium in the Pathogenesis and Therapy of Bronchial Asthma. Przegl Lek. 1997;54(9):630-03. Review.
16. View Abstract: Tosiello L. Hypomagnesemia and Diabetes Mellitus. A Review of Clinical Implications. Arch Intern Med. Jun1996;156(11):1143-48.
17. View Abstract: Johansson G, et al. Effects of Magnesium Hydroxide in Renal Stone Disease. J Am Coll Nutr. 1982;1(2):179-85.
18. View Abstract: Angus RM, et al. Dietary Intake and Bone Mineral Density. Bone Miner. Jul1988;4(3):265-77.
19. View Abstract: Rude RK, et al. Magnesium deficiency-induced osteoporosis in the rat: uncoupling of bone formation and bone resorption. Magnes Res. Dec1999;12(4):257-67.
20. Gaby AR. Magnesium: An Inexpensive, Safe, and Effective Treatment for Cardiovascular Disease. J Advancement Med. 1986;1:179-81.
21. View Abstract: Kh R, et al. Effect of oral magnesium supplementation on blood pressure, platelet aggregation and calcium handling in deoxycorticosterone acetate induced hypertension in rats. J Hypertens. Jul2000;18(7):919-26.
22. View Abstract: Facchinetti F, et al. Oral Magnesium Successfully Relieves Premenstrual Mood Changes. Obstet Gynecol. Aug1991;78(2):177-81.