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What does it do? Magnesium is needed for bone, protein, and fatty acid formation, making new cells, activating B vitamins, relaxing muscles, clotting blood, and forming ATP—the energy the body runs on. The secretion and action of insulin also require magnesium.
Magnesium also acts in a way related to calcium channel blocker drugs. This effect may be responsible for the fact that under certain circumstances, magnesium has been found to potentially improve vision in people with glaucoma.1 Similarly, this action might account for magnesium's ability to lower blood pressure.2
Since magnesium has so many different actions in the body, the exact reasons for some of its clinical effects are difficult to determine. For example, magnesium has reduced hyperactivity in children in preliminary research.3 Other research suggests that some children with attention deficit-hyperactivity disorder (ADHD) have lowered levels of magnesium. In a preliminary but controlled trial, 50 ADHD children with low magnesium (as determined by red blood cell, hair, and serum levels of magnesium) were given 200 mg of magnesium per day for six months.4 Compared with 25 other magnesium-deficient ADHD children, those given magnesium supplementation had a significant decrease in hyperactive behavior.
Magnesium levels have been reported to be low in those with chronic fatigue syndrome (CFS),5 while magnesium injections have been reported to improve symptoms.6 Oral magnesium supplementation has also improved symptoms in those people with CFS who had low magnesium levels in another report, although magnesium injections were sometimes necessary.7 However, other research reports no evidence of magnesium deficiency in people with CFS.8 9 The reason for this discrepancy remains unclear. People with CFS considering magnesium supplementation should have their magnesium status checked beforehand by a doctor. Only people with magnesium deficiency appear to benefit from this therapy.
People with diabetes tend to have lower magnesium levels compared with those who have normal glucose tolerance.10 Supplementation with magnesium overcomes this problem11 and may help some diabetics improve glucose tolerance.
Magnesium may be beneficial for bladder problems in women, especially common disturbances in bladder control and the sense of "urgency." A double-blind trial found that women who took 350 mg of magnesium hydroxide (providing 147 mg elemental magnesium) twice daily for four weeks, had better bladder control and fewer symptoms than women who took a placebo.12
Magnesium supplementation may reduce dehydration of red blood cells in sickle cell anemia patients. Administration of 540 mg per day of magnesium pidolate to sickle cell anemia patients was seen after six months, to reverse some of the characteristic red blood cell abnormalities and to dramatically reduce the number of painful days for these patients.13 This preliminary trial was not blinded, so placebo effect could not be ruled out. Magnesium pidolate is also an unusual form of magnesium. It is unknown whether other forms of magnesium would produce similar results.
Where is it found? Nuts and grains are good sources of magnesium. Beans, dark green vegetables, fish, and meat also contain significant amounts.
Who is likely to be deficient? Magnesium deficiency is common in people taking "potassium-depleting" prescription diuretics. Taking too many laxatives can also lead to deficiency. Alcoholism, severe burns, diabetes, and heart failure are other potential causes of deficiency. In a study of urban African-American people (predominantly female), the overall prevalence of magnesium deficiency was 20%. People with a history of alcoholism were six times more likely to have magnesium deficiency than were people without such a history.14 The low magnesium status seen in alcoholics with liver cirrhosis contributes to the development of hypertension in these people.15
Almost two-thirds of people in intensive care hospital units have been found to be magnesium deficient.16 Deficiency may also occur in people with chronic diarrhea, pancreatitis, and other conditions associated with malabsorption.
Fatigue, abnormal heart rhythms, muscle weakness and spasm, depression, loss of appetite, listlessness, and potassium depletion can all result from a magnesium deficiency. People with these symptoms should be evaluated by a doctor before taking magnesium supplements.
As previously mentioned, magnesium levels have been found to be low in people with chronic fatigue syndrome.
Deficiencies of magnesium that are serious enough to cause symptoms should be treated by medical doctors, as they might require intravenous administration of magnesium.17
How much is usually taken? Most people don't consume enough magnesium in their diets. Many nutritionally oriented doctors recommend 250–350 mg per day of supplemental magnesium for adults.
Are there any side effects or interactions? Comments in this section are limited to effects from taking oral magnesium. Side effects from intravenous use of magnesium are not discussed.
Taking too much magnesium often leads to diarrhea. For some people this can happen with amounts as low as 350–500 mg per day. More serious problems can develop with excessive magnesium intake from magnesium-containing laxatives. However, the amounts of magnesium found in nutritional supplements are unlikely to cause such problems. People with kidney disease should not take magnesium supplements without consulting a doctor.
Vitamin B6 increases the amount of magnesium that can enter cells. As a result, these two nutrients are often taken together. Magnesium may compete for absorption with other minerals, particularly calcium. Taking a multimineral supplement avoids this potential problem.
Magnesium also acts in a way related to calcium channel blocker drugs. This effect may be responsible for the fact that under certain circumstances, magnesium has been found to potentially improve vision in people with glaucoma.1 Similarly, this action might account for magnesium's ability to lower blood pressure.2
Since magnesium has so many different actions in the body, the exact reasons for some of its clinical effects are difficult to determine. For example, magnesium has reduced hyperactivity in children in preliminary research.3 Other research suggests that some children with attention deficit-hyperactivity disorder (ADHD) have lowered levels of magnesium. In a preliminary but controlled trial, 50 ADHD children with low magnesium (as determined by red blood cell, hair, and serum levels of magnesium) were given 200 mg of magnesium per day for six months.4 Compared with 25 other magnesium-deficient ADHD children, those given magnesium supplementation had a significant decrease in hyperactive behavior.
Magnesium levels have been reported to be low in those with chronic fatigue syndrome (CFS),5 while magnesium injections have been reported to improve symptoms.6 Oral magnesium supplementation has also improved symptoms in those people with CFS who had low magnesium levels in another report, although magnesium injections were sometimes necessary.7 However, other research reports no evidence of magnesium deficiency in people with CFS.8 9 The reason for this discrepancy remains unclear. People with CFS considering magnesium supplementation should have their magnesium status checked beforehand by a doctor. Only people with magnesium deficiency appear to benefit from this therapy.
People with diabetes tend to have lower magnesium levels compared with those who have normal glucose tolerance.10 Supplementation with magnesium overcomes this problem11 and may help some diabetics improve glucose tolerance.
Magnesium may be beneficial for bladder problems in women, especially common disturbances in bladder control and the sense of "urgency." A double-blind trial found that women who took 350 mg of magnesium hydroxide (providing 147 mg elemental magnesium) twice daily for four weeks, had better bladder control and fewer symptoms than women who took a placebo.12
Magnesium supplementation may reduce dehydration of red blood cells in sickle cell anemia patients. Administration of 540 mg per day of magnesium pidolate to sickle cell anemia patients was seen after six months, to reverse some of the characteristic red blood cell abnormalities and to dramatically reduce the number of painful days for these patients.13 This preliminary trial was not blinded, so placebo effect could not be ruled out. Magnesium pidolate is also an unusual form of magnesium. It is unknown whether other forms of magnesium would produce similar results.
Where is it found? Nuts and grains are good sources of magnesium. Beans, dark green vegetables, fish, and meat also contain significant amounts.
Who is likely to be deficient? Magnesium deficiency is common in people taking "potassium-depleting" prescription diuretics. Taking too many laxatives can also lead to deficiency. Alcoholism, severe burns, diabetes, and heart failure are other potential causes of deficiency. In a study of urban African-American people (predominantly female), the overall prevalence of magnesium deficiency was 20%. People with a history of alcoholism were six times more likely to have magnesium deficiency than were people without such a history.14 The low magnesium status seen in alcoholics with liver cirrhosis contributes to the development of hypertension in these people.15
Almost two-thirds of people in intensive care hospital units have been found to be magnesium deficient.16 Deficiency may also occur in people with chronic diarrhea, pancreatitis, and other conditions associated with malabsorption.
Fatigue, abnormal heart rhythms, muscle weakness and spasm, depression, loss of appetite, listlessness, and potassium depletion can all result from a magnesium deficiency. People with these symptoms should be evaluated by a doctor before taking magnesium supplements.
As previously mentioned, magnesium levels have been found to be low in people with chronic fatigue syndrome.
Deficiencies of magnesium that are serious enough to cause symptoms should be treated by medical doctors, as they might require intravenous administration of magnesium.17
How much is usually taken? Most people don't consume enough magnesium in their diets. Many nutritionally oriented doctors recommend 250–350 mg per day of supplemental magnesium for adults.
Are there any side effects or interactions? Comments in this section are limited to effects from taking oral magnesium. Side effects from intravenous use of magnesium are not discussed.
Taking too much magnesium often leads to diarrhea. For some people this can happen with amounts as low as 350–500 mg per day. More serious problems can develop with excessive magnesium intake from magnesium-containing laxatives. However, the amounts of magnesium found in nutritional supplements are unlikely to cause such problems. People with kidney disease should not take magnesium supplements without consulting a doctor.
Vitamin B6 increases the amount of magnesium that can enter cells. As a result, these two nutrients are often taken together. Magnesium may compete for absorption with other minerals, particularly calcium. Taking a multimineral supplement avoids this potential problem.