Magnesium is essential to many metabolic reactions, including lipid
metabolism, amino acid activation, the glycolytic cycle, and the citric acid
cycle. Its primary function is as an enzyme cofactor, thus producing energy,
synthesizing lipids and proteins, regulating calcium flow and parathyroid
hormone (PTH) secretion, forming urea, and relaxing muscles. Vitamin
B6 works with magnesium in many enzyme systems and assists in the
body's accumulation of magnesium.
Dietary intake is generally thought to be insufficient, although clinical
depletion is rare in Americans. One problem in determining actual dietary intake
is that a number of foods have not been thoroughly analyzed, and laboratory
analysis of magnesium contents often do not agree with food composition tables.
However, inadequate dietary intake is not usually the sole cause of deficiency.
Proper balance also depends on efficient intestinal and renal absorption and
excretion. Risk factors for depletion include gastrointestinal disorders, such
as inflammatory bowel disease, pancreatitis, fatty acid malabsorption, ileal
dysfunction, and gastrointestinal infections (viral, bacterial, or protozoan)
that result in malabsorption or vomiting and diarrhea; renal dysfunction with
excessive urine loss; nephrotoxic and diuretic drugs; and endocrine disorders,
such as hyperthyroidism, diabetes mellitus, and hyperparathyroidism with
Magnesium deficiency most severely affects cardiovascular, neuromuscular, and
renal tissues, and has been linked to agitation, anemia (hemolytic), anorexia,
anxiety, ataxia, cardiac arrhythmias, confusion, Crohn's disease, depression,
disorientation, fasciculations, hallucinations, heart disease, heart attacks
resulting from coronary artery spasm, heart failure from defibrillation,
hyperactivity, hypertension, insomnia, irritability, kidney stones, muscle
pains, muscular weakness, nausea and vomiting, nervousness, nystagmus,
neuromuscular irritability, organic brain syndrome, paresthesias, pronounced
startle response, restlessness, seizures, sonophobia, tachycardia, increased
triglyceride levels, and vertigo.
Increased levels of magnesium sulfate from treatment of preeclampsia or other
problems of pregnancy have been associated with significantly reduced risks of
cerebral palsy and possibly mental retardation in very-low-birth-weight infants;
however, a preliminary report of a recent study is contradictory. Use of
magnesium to prevent premature labor at less than 34 weeks' gestation in women
who are not preeclamptic is disputed. In a recent study, use of MgSO4 (magnesium
sulfate) as a randomized treatment for such women was associated with higher
infant mortality, and the study was stopped.
- Rich sources: tofu, legumes, whole grains, green leafy vegetables,
wheat bran, Brazil nuts, soybean flour, almonds, cashews, blackstrap molasses,
pumpkin and squash seeds, pine nuts, black walnuts
- Good sources: peanuts, whole wheat flour, oat flour, beet greens,
spinach, pistachio nuts, shredded wheat, bran cereals, oatmeal, bananas, baked
potatoes (with skin)
- Many herbs, spices, and seaweeds supply magnesium (e.g., agar
seaweed, coriander, dill weed, celery seed, sage, dried mustard, basil, cocoa
powder, fennel seed, savory, cumin seed, tarragon, marjoram, poppy seed)
The magnesium ion (Mg2+) forms complexes with many types of
organic molecules. It binds with phosphates, and weakly with carboxylates and
hydroxyls. Magnesium stabilizes many ribonucleotides and deoxyribonucleotides,
inducing important physicochemical changes.
Supplementary magnesium is available in several varieties of salts.
- Magnesium citrate, magnesium gluconate, and magnesium lactate are
more soluble and bioavailable than magnesium oxide.
- Magnesium chloride is more soluble than magnesium oxide, gluconate,
citrate, hydroxide, and sulfate, and does not require stomach acid for
solubility, but its use is limited due to its hygroscopic properties.
- Magnesium hydroxide (milk of magnesia)
- Magnesium sulfate (Epsom
- Cardiovascular: to prevent atherosclerosis and myocardial infarction,
reduce high blood pressure, treat angina, prevent strokes, improve cholesterol
and triglyceride levels
- Cardiac arrhythmia: to inhibit triggered beats arising from early
afterdepolarizations, treat congenital long QT syndrome (torsade de
- Lung function: to halt acute asthma attacks and acute exacerbations
of chronic obstructive pulmonary disease, reduce recurrence of apnea in
- Diabetes: to improve insulin action and glucose metabolism, decrease
insulin need, ease diabetic blood pressure
- Hearing: to prevent noise-induced hearing loss
- Glaucoma: to improve peripheral circulation and visual
- Fatigue: to improve sleep, restore normal energy level
- Mental health: to reduce nervousness, anxiety, and
- Migraines: to treat food allergy–induced
migraine headaches using ionized magnesium
- Pregnancy: to lower blood pressure, prevent preeclampsia and
- Renal: to prevent kidney stones
- Menstruation and premenstrual syndrome (PMS): to relieve menstrual
cramps, irritability, fatigue, depression, and water retention
|Dosage Ranges and Duration of
Recommendations for adequate magnesium intake promulgated by the Food and
Nutrition Board of the Institute of Medicine in 1997:
- Birth to 6 months: 30 mg/day
- 6 months to 1 year: 75 mg/day
- 1 to 3 years: 80 mg/day
- 4 to 8 years: 130 mg/day
- 9 to 13 years: 240 mg/day
- 14 to 18 years (boys): 410 mg/day
- 14 to 18 years (girls): 360 mg/day
- 19 to 30 years (men): 400 mg/day
- 19 to 30 years (women): 310 mg/day
- 31+ years (men): 420 mg/day
- 31+ years (women): 320 mg/day
- Up to 18 years: 400 mg/day
- 19 to 30 years: 350 mg/day
- 31 to 50 years: 360 mg/day
- Up to 18 years: 360 mg/day
- 19 to 30 years: 310 mg/day
- 31 to 50 years: 320 mg/day
These represent significant increases for adolescents and adults from the
recommended dietary allowance promulgated by the National Academy of Sciences in
1989. Supplementation should be in small doses three to six times throughout the
day with a full glass of water to reduce chance of
Nutritional toxicity is rare. Symptomatic magnesium excess may occur in
patients with gastrointestinal disorders and renal insufficiency when
magnesium-based laxatives or antacids are taken. With increasing
hypermagnesemia, the effects are lowered blood pressure, nausea, vomiting,
brachycardia, and urinary retention (serum levels as low as 3 mEq/L), mental
status changes, electrocardiographic changes (longer PR and QT intervals),
central nervous system depression, severe respiratory depression, coma, and
cardiac arrest (at or near 15 mEq/L).
Individuals with severe heart disease (such as high-grade atrioventricular
block) should take magnesium only on the advice of their physician.
Individuals with kidney disease should not take more than 3,000 mg per
Overuse of magnesium hydroxide (milk of magnesia) as a laxative or antacid,
or magnesium sulfate (Epsom salts) as a laxative and tonic, may cause
deficiencies of other minerals or lead to toxicity.
Magnesium salts or magnesium-containing antacids interfere with absorption of
tiludronate, a bisphosphonate drug similar to alendronate (PDR 1998). This
interaction has not been reported with alendronate. However, calcium and other
minerals should be taken at least two hours before or after alendronate
administration to minimize interference with the absorption of the
Magnesium sulfate may interact with calcium channel blockers and decrease
cardiac function, particularly in pregnant women (Davis et al. 1997). However,
another report indicates that using magnesium-enriched salt as a substitute for
sodium enhances the cardiovascular effects derived from the combination of low
dose felodipine and ramipril in rats (Mervaala et al.
Hypomagnesemia increases the risk of cardiac glycoside toxicity (Whang et al.
1985). Digoxin decreases the reabsorption of magnesium from the kidneys, which
leads to increased excretion in the urine (Crippa et al. 1999). However,
adequate amounts of magnesium enhance the antiarrhythmic activity of this drug,
particularly by diminishing the ventricular response during atrial fibrillation.
One case report describes a patient with digoxin toxicity associated with
ventricular tachycardia (Kinlay and Buckley 1995). Treatment with magnesium
sulfate (two doses of 10 mmol IV) resulted in a more stable junctional rhythm.
Normal magnesium levels should be maintained during digoxin
In a controlled clinical study with 25 healthy women at or past menopause and
15 healthy women of child-bearing age, serum levels of magnesium were inversely
related to the serum level of estrogen in both groups (Muneyyirci-Delale et al.
1999). Another group of postmenopausal women treated with conjugated estrogens
and medroxyprogesterone for one year had reduced urinary excretion of zinc and
magnesium (Herzberg et al. 1996). The clinical significance of this interaction
is unknown. Glipizide;
Concomitant ingestion of magnesium hydroxide with both glipizide and
glyburide has been shown to increase the rate and extent of absorption of these
medications (Kivisto and Neuvonen 1991; Lehto et al. 1996; Neuvonen and Kivisto
1994). The faster rate of absorption may result in increased early insulin and
glucose responses (Kivisto and Neuvonen 1991). This effect was observed with
magnesium hydroxide antacids, not dietary
Supplementation with magnesium in patients with type II diabetes mellitus
enhances insulin sensitivity and secretion (De Valk 1999). In rats predisposed
to type II diabetes, supplementation with oral magnesium diminished the
progression of the
Magnesium salts decrease the rate and extent of absorption of nitrofurantoin
(Naggar and Khalil 1979). It is not known if dietary supplements containing
magnesium will have a similar effect on nitrofurantoin
Penicillamine can inactivate magnesium, particularly when high doses are used
over a long period of time (Seelig 1982). However, supplementation with
magnesium and other nutrients in over 50 patients on penicillamine therapy for
the treatment of autoimmune disorders resulted in fewer adverse reactions than
those commonly experienced in patients treated with the drug
Quinolone antibiotics form chelates with metal cations, such as aluminum,
magnesium, calcium, iron, zinc, copper, and manganese (Kara et al. 1991; Li et
al. 1999), which significantly reduces the absorption of these medications
(Balfour and Wiseman 1999; Brouwers 1992; Campbell and Hasinoff 1991). Dietary
supplements and antacids containing aluminum and magnesium should be taken two
to four hours before or after administration of these antibiotics (Hines Burnham
Tetracyclines form chelates with divalent and trivalent cations, including
iron, aluminum, magnesium, and calcium (Neuvonen 1976). It has been reported
that these chelates are poorly soluble and can significantly reduce the
absorption and efficacy of tetracyclines (Hines Burnham et al. 2000; Neuvonen
1976). However, one study reports that magnesium-tetracycline complexes may be
more bioavailable than uncomplexed tetracycline due to a higher degree of
membrane diffusion (Lambs et al. 1984).
Balfour JA, Wiseman LR. Moxifloxacin. Drugs. 1999;57(3):363-374.
Britton J, Pavord I, Richards K, Wisniewski A, Knox A, Lewis S. Dietary
magnesium, lung function, wheezing, and airway hyperactivity in a random adult
population sample. Lancet. 1994; 344:357-362.
Brouwers JR. Drug interactions with quinolone antibacterials. Drug Saf.
Campbell NR, Hasinoff BB. Iron supplements: a common cause of drug
interactions. Br J Clin Pharmacol. 1991;31(3):251-255.
Crippa G, Sverzellati E, Girogi Pierfranceschi M, et al. Magnesium and
cardiovascular drugs: interactions and therapeutic role. Ann Ital Med
Davis WB, Wells SR, Kuller JA, et al. Analysis of the risks associated with
calcium channel blockade: implications for the obstetrician-gynecologist.
Obstet Gynecol Surv. 1997;52(3):198-201.
De Valk HW. Magnesium in diabetes mellitus. Neth J Med. 1999:
Ensminger AH, Ensminger ME, Konlande JE, Robson JRK. Foods and Nutrition
Encyclopedia. 2nd ed. Boca Raton, Fla: CRC Press Inc; 1994;2:1338-1341.
Garrison RH Jr, Somer E. The Nutrition Desk Reference. 3rd ed. New
Canaan, Conn: Keats Publishing Inc; 1995:158-165.
Hardman JG, Gilman AG, Limbird LE, eds. Goodman and Gilman's
Pharmacological Basis of Therapeutics. 9th ed. New York, NY: McGraw-Hill;
Heinerman J. Heinerman's Encyclopedia of Nature's Vitamins and
Minerals. Paramus, NJ: Prentice Hall Inc; 1998:296-302.
Herzberg M, Lusky A, Blonder J, Frenkel Y. The effect of estrogen replacement
therapy on zinc in serum and urine. Obstet Gynecol.
Hines Burnham T, et al, eds. Drug Facts and Comparisons. St. Louis,
MO:Facts and Comparisons;2000:1286.
Kara M, Hasinoff BB, McKay DW, et al. Clinical and chemical interactions
between iron preparations and ciprofloxacin. Br J Clin Pharmacol.
Kinlay S, Buckley NA. Magnesium sulfate in the treatment of ventricular
arrhythmias due to digoxin toxicity. J Toxicol Clin Toxicol.
Kivisto KT, Neuvonen PJ. Enhancement of absorption and effect of glipizide by
magnesium hydroxide. Clin Pharmacol Ther. 1991;49(1):39-43.
Lambs L, Brion M, Berthon G. Metal ion-tetracycline interactions in
biological fluids. Part 3. Formation of mixed-metal ternary complexes of
tetracycline, oxytetracycline, doxycycline and minocycline with calcium and
magnesium, and their involvement in the bioavailability of these antibiotics in
blood plasma. Agents Actions. 1984;14:743-750.
Lehto P, Laine K, Kivisto KT, et al. The effect of pH on the in-vitro
dissolution of three second-generation sulphoylurea preparations: mechanism of
antacid-sulphonylurea interaction. J Pharm Pharmacol.
Li RC, Lo KN, Lam JS, et al. Effects of order of magnesium exposure on the
postantibiotic effect and bactericidal activity of ciprofloxacin. J
Mervaala EM, Malmberg L, Teravainen TL, Laakso J, Vapaatalo H, Karppanen H.
Influence of dietary salts on the cardiovascular effects of low-dose combination
of ramipril and felodipine in spontaneously hypertensive rats. Br J
Muneyyirci-Delale O, Nacharaju VL, Dalloul M, Altura BM, Altura BT. Serum
ionized magnesium and calcium in women after menopause: Inverse relation of
estrogen with ionized magnesium. Fertil Steril. 1999;71:869-872.
Murray MT. Encyclopedia of Nutritional Supplements. Rocklin, Calif:
Prima Publishing; 1996:159-175.
Naggar VF, Khalil SA. Effect of magnesium trisilicate on nitrofurantoin
absorption. Clin Pharmacol Ther. 1979;25(6):857-863.
Neuvonen PJ. Interactions with the absorption of tetracyclines. Drugs.
Neuvonen PJ, Kivisto KT. Enhancement of drug absorption by antacids. An
unrecognized drug interaction. Clin Pharmacokinet.
Posaci C, Erten O, Uren A, Acar B. Plasma copper, zinc and magnesium levels
in patients with premenstrual tensions syndrome. Obstetricia et Gynecologica
Physicians' Desk Reference, PDR. 52nd ed. Montvale, NJ: Medical
Economics Company; 1998.
Romano TJ. Magnesium deficiency in systemic lupus erythematosus. J Nutr
Environ Med. 1997;7:107-111.
Romano TJ, Stiller JW. Magnesium deficiency in fibromyalgia syndrome. J
Nutr Med. 1994;4:165-167.
Sacks FM, Willett WC, Smith A, Brown LB, Rosner B, Moore TJ. Effect on blood
pressure of potassium, calcium, and magnesium in women with low habitual intake.
Seelig MS. Auto-immune complications of D-penicillamine - a possible result
of zinc and magnesium depletion and of pyridoxine inactivation. J Am Coll
Nutr. 1982: 1(2):207-214.
Shils ME, Olson JA, Shike M, Ross AC. Modern Nutrition in Health and
Disease. 9th ed. Baltimore, Md: Williams & Wilkins; 1999:169-192,
Werbach MR. Nutritional Influences on Illness. 2nd ed. Tarzana, Calif:
Third Line Press; 1993:655-680.
Whang R, Oei TO, Watanabe A. Frequency of hypomagnesia in hospitalized
patients receiving digitalis. Arch Intern Med.
Copyright © 2000 Integrative Medicine
CommunicationsThis publication contains
information relating to general principles
of medical care that should not in any event be construed as specific
instructions for individual patients. The publisher does not accept any
responsibility for the accuracy of the information or the consequences arising
from the application, use, or misuse of any of the information contained herein,
including any injury and/or damage to any person or property as a matter of
product liability, negligence, or otherwise. No warranty, expressed or implied,
is made in regard to the contents of this material. No claims or endorsements
are made for any drugs or compounds currently marketed or in investigative use.
The reader is advised to check product information (including package inserts)
for changes and new information regarding dosage, precautions, warnings,
interactions, and contraindications before administering any drug, herb, or
supplement discussed herein.