Bottom Line: Clinical trials show that magnesium supplements can lower blood pressure slightly and may prevent premenstrual syndrome (PMS). Oral magnesium supplements should not be confused with intravenous magnesium, which is used for certain medical conditions.
Magnesium is a mineral found in foods such as nuts, beans, whole grains, dark green vegetables, oysters, and meats. It is necessary for a great amount of the body's physiological processes.. Magnesium is also important for maintaining the structure of the cell and for sending signals within cells. Magnesium supplements have been shown to help women suffering from conditions such as premenstrual syndrome and high blood pressure. In children and adolescents, magnesium supplements may increase bone mass and improve asthma, but scientists are still unsure how taking excess magnesium would cause these effects.
To treat asthma Several clinical trials have studied the use of intravenous or nebulized magnesium sulfate for asthma. One small clinical trial of children showed that along with conventional treatment, over-the-counter magnesium supplements, taken by mouth, can improve asthma.
To treat heart disease Clinical trials show that magnesium supplements have a consistent, but small lowering effect on blood pressure. There is no other evidence to support this use.
To treat chronic fatigue syndrome In one clinical trial, magnesium supplements helped improve the symptoms of chronic fatigue syndrome.
To prevent glaucoma No scientific evidence supports this use.
To lower high blood pressure Clinical trials show that magnesium supplements have a consistent, but small lowering effect on blood pressure.
To relieve muscle pain No scientific evidence supports this use.
To treat osteoporosis No scientific evidence supports this use. However, a small clinical trial showed that magnesium supplementation increased bone mass in adolescent girls.
As a nutritional supplement right before and after giving birth Several clinical trials have studied the use of intravenous magnesium sulfate for hypertension and preeclampsia in pregnant women, but there is no proof from clinical trials that magnesium supplements, taken by mouth, can prevent these conditions.
To prevent and treat premenstrual syndrome (PMS) Several clinical trials support this use.
High blood pressure In a randomized controlled trial, magnesium supplements were tested 91 in women with mild to moderate high blood pressure. These women were not currently taking any other medications to reduce their blood pressure. After six months of taking either 485 mg of elemental magnesium or a placebo pill daily, the women taking magnesium had slightly lower blood pressure than when the trial started. However, additional clinical trials are needed to establish the usefulness of magnesium in treating hypertension.
Premenstrual syndrome (PMS) Thirty-two women who chronically suffered from premenstrual syndrome (PMS) took part in a study to see if magnesium supplements would improve their symptoms. The women took either 360 mg of elemental magnesium or a placebo pill daily, starting on the 15th day of their cycle and ending when menstruation began. After only two months of using magnesium, women reported that their PMS symptoms had improved. Although this study supports the use of magnesium for the short-term relief of PMS, it is important that future studies look at the safety and effectiveness of long-term use of magnesium supplements.
Alcohol-induced liver damage The result of magnesium supplementation (500 mg daily) on liver damage was tested in 118 alcoholic participants. After 8 weeks of magnesium or placebo, liver enzymes (a measure of liver damage) were tested, and one enzyme, serum aspartate-aminotransferase (AST), was lowered in the subjects who took magnesium. Additional clinical trials are needed to establish the usefulness of magnesium in treating liver damage in alcoholics.
Bone mass In a randomized, placebo-controlled study, oral magnesium or placebo was given to 50 adolescent girls whose dietary magnesium intake was relatively low. After 1 year, bone mass was determined. The girls that received magnesium had greater increases in overall hip bone mass compared to the placebo group. Further studies are needed to determine the long-term effects of magnesium supplementation in female and male adolescents.
This product is regulated by the FDA as a dietary supplement. Unlike approved drugs, supplements are not required to be manufactured under specific standardized conditions. This product may not contain the labeled amount or may be contaminated. In addition, it may not have been tested for safety or effectiveness.
You have kidney problems such as renal insufficiency or end-stage renal disease.
You are a patient with heart block (a conduction disturbance in the heart).
You are taking digoxin (When taken at the same time, magnesium supplements can reduce the absorption of digoxin into the bloodstream).
You are taking tetracycline antibiotics (Magnesium may reduce the absorption and blood levels of these medications).
You are taking nitrofurantoin (When taken at the same time, magnesium can complex with nitrofurantoin, reducing its availability for absorption into the bloodstream).
You are taking neuromuscular blockers (e.g. vecuronium, succinylcholine) (Magnesium supplements may have additive effects).
You are taking folate, iron, or IP-6 supplements (Because magnesium can reduce their absorption into the bloodstream these supplements should be taken either two hours before or after taking magnesium).
High doses of magnesium can cause diarrhea, nausea, vomiting, cramps, and a chalky taste in the mouth.
Toxicity from magnesium overdose is relatively rare, but it can cause nausea, vomiting, lethargy, confusion, reduced breathing rate, low blood pressure, slow heart rate, heart block (a conduction disturbance in the heart), and cardiac arrest. This toxicity occurs most often in patients with kidney problems.
Clinical data suggest that magnesium supplements may benefit PMS, some heart conditions, diabetes, chronic fatigue, and in conjunction with calcium for osteoporosis. Additional research is under way for treating migraines.
An essential mineral obtained from foods such as nuts, grains, vegetables and meats, magnesium is used by patients to prevent and treat fatigue, migraines, premenstrual syndrome, and heart disease (1). It is essential for numerous biochemical processes, including the formation of ATP, cellular signal transduction, synthesis of DNA, RNA and protein, and formation of bone. Clinical data suggest that magnesium supplementation may benefit PMS (2), some heart conditions (3), diabetes, chronic fatigue, alcohol-induced liver disease (4) and in conjunction with calcium for osteoporosis. Also, supplementation increased bone mineral content in adolescent girls (5) and improved asthma in children (6). Additional research is under way for migraine prophylaxis. Diarrhea is the primary reported adverse event (7). Patients with renal insufficiency or heart block should not self-medicate with magnesium supplements.
Magnesium is required for many biochemical processes including, approximately 300 enzyme systems, for anaerobic and aerobic pathways, and for forming the Mg-ATP complex. It is essential for DNA, RNA, protein, carbohydrate, and lipid synthesis. Magnesium ions play a structural role, where they are bound to phospholipid membranes, ribosomes, and chromatin. Enzymes that are used in transmitting signals within cells also require magnesium ions including adenylate cyclase, which catalyzes the synthesis of cyclic AMP, and protein kinase-C, which catalyzes the phosphorylation of a number of proteins. Magnesium is also used by muscle proteins, including creatinine kinase, actin, sodium-potassium ATPase, and calcium pumps. It is vital for energy production, as it is required by the F1 protein, the ATP-synthesizing protein in the mitochondrion. Magnesium is an N-methyl-D-aspartic acid (NMDA) receptor antagonist, which may account for its analgesic effects. In addition, magnesium may beneficially influence cardiovascular disease through reducing catecholamine excretion (8). (9)(10)
Absorption Magnesium is absorbed primarily in the distal small intestines or colon. Active uptake is required involving various transport systems such as the vitamin D-sensitive transport system. Since magnesium is not passively absorbed, it demonstrates saturable absorption resulting in variable bioavailability averaging 35-40% of administered dose. Magnesium levels in the body, presence of calcium, phosphate, phytate, and protein can affect rate of absorption. Distribution Normal plasma levels of magnesium range from about 1.6 to 2.1 nM. Magnesium rapidly distributes throughout the body following absorption. About half of the plasma magnesium occurs as the free ion, with about one-third bound to albumin and the remainder occurring in complexes with phosphate, citrate, and other anions. The non-protein-bound magnesium (70% of total magnesium) in the plasma can enter the glomerular filtrate. Nearly all of the magnesium entering the filtrate is reabsorbed by the renal tubule. About 60 to 65% of the body's magnesium is in bone, 27% in muscle, 6% in other cells, and about 1% in extracellular fluids. About 20 to 30% of bone magnesium is freely exchangeable and is in rapid equilibrium with serum. The remaining bone magnesium is intimately associated with the apatite crystal of the bone and is called non-exchangeable magnesium Metabolism/Excretion Magnesium is regulated and excreted primarily by the kidneys where various ATPases are responsible for maintaining homeostasis. Magnesium also undergoes efficient enterohepatic circulation. (10)(11)(12)
Patients with renal insufficiency or end-stage renal disease should not consume magnesium supplements. Patients with heart block should not consume magnesium supplements.
Common: Elevated doses of magnesium can cause osmotic diarrhea, nausea, vomiting, cramps, and a chalky taste in the mouth (7). Toxicity: Hypermagnesemia is relatively rare. Cardiac and neurologic symptoms of hypermagnesemia generally do not occur until serum levels exceed 2-4 mmol/L. Common symptoms of severe hypermagnesemia include nausea, vomiting, lethargy, confusion, respiratory depression, hypotension, bradycardia, heart block, and cardiac arrest. The most frequent cause of death from hypermagnesemia is respiratory arrest. Severe symptomatic hypermagnesemia predominantly occurs in patients with renal insufficiency (13).
Digoxin: Magnesium supplements may reduce the bioavailability of digoxin when taken concomitantly. Tetracyclines: Magnesium may reduce the absorption and serum levels of tetracycline antibiotics. Nitrofurantoin: Magnesium may adsorb to nitrofurantoin, reducing its bioavailability. Neuromuscular blockers: Magnesium supplements may potentiate the effects of neuromuscular blockers (e.g., vecuronium and succinylcholine) (14). Nutrient Interactions: Folate or iron supplements should be taken 2 hours apart. Magnesium should also not be taken with high phytate food (7).
Witteman JC, et al. Reduction of blood pressure with oral magnesium supplementation in women with mild to moderate hypertension. Am J Clin Nutr 1994;60:129-35. A prospective, randomized, double-blind evaluation of magnesium supplementation for reduction of blood pressure in 91 women ages 35-77 years with mild to moderate hypertension not currently receiving pharmacologic therapy. Patients were randomized to 485 mg per day elemental magnesium or placebo for 6 months. Change in blood pressure was the primary outcome measured. Rate of adverse effects were similar between treatment groups. Although the study results suggest supplementation may lower blood pressure, it is not a clinically meaningful change. Additional studies in homogeneous populations are necessary.
Facchinetti F, et al. Oral magnesium successfully relieves premenstrual mood changes. Obstet Gynecol 1991;78:177-81. A prospective, randomized, double-blind evaluation of magnesium supplementation from the 15th day of the cycle until menstruation on 32 women suffering from chronic PMS. Following a 2-month baseline period, subjects were randomized to receive magnesium pyrrolidine carboxylic acid containing 360 mg elemental magnesium (n = 14) or placebo (n = 14) for 2 menstrual cycles; all subjects subsequently received magnesium supplements for an additional 2 cycles. Primary outcomes measured were Menstrual Distress Questionnaire and magnesium and hormone serum levels. Four patients withdrew from the study, one from the magnesium group due to diarrhea. Questionnaire total scores were significantly lower after 2 months of magnesium supplementation. Cellular concentration of magnesium was significantly elevated while hormone levels were unchanged. The data suggests that magnesium supplementation reduces cluster pain and overall menstrual distress, although additional studies are required to determine long term effects.
Poikolainen K, Alho H. Magnesium treatment in alcoholics: a randomized clinical trial. Subst Abuse Treat Prev Policy. 2008;3:1. Decreased magnesium may mediate alcohol-induced liver damage. In this randomized, double-blind, placebo-controlled trial, the effects of magnesium supplementation (500 mg daily) on liver enzyme levels were analyzed in 118 alcoholic participants who were initially treated for alcohol withdrawal symptoms. After 8 weeks, serum aspartate-aminotransferase (AST) activity but not serum gammaglutamyltransferase (GGT) and alanine-aminotransferase (ALT) activities were reduced in the participants receiving magnesium as compared to the control group. Larger, long-term studies are necessary to determine the clinical significance of magnesium supplementation for alcoholic liver disease.
Carpenter TO, et al. A randomized controlled study of effects of dietary magnesium oxide supplementation on bone mineral content in healthy girls. J Clin Endocrinol Metab. Dec 2006;91(12):4866-4872. To determine if oral magnesium supplementation in adolescent girls (8-14 y) with relative magnesium undernutrition (<220 mg daily) could alter bone mineral content (BMC), a randomized, placebo-controlled study was performed. Fifty participants either received magnesium (300 mg daily) or placebo for 1 year after which the BMC of various areas (total hip, femoral neck, Ward's area, and lumbar spine, L1-L4) was determined. Greater increases in overall hip BMC were detected in the treatment group as compared to the placebo group. Further studies are required to determine the long-term effects of magnesium supplementation in female as well as male adolescents.
