I must state upfront this artical comes from :http://www.vitamin-update.com/definition.cfm/id/33.html
None of what is written below is my work but I found the article extremly interesting, I use magnesium for muscle spasms in my clients and find it works quite well. I trust you find it interesting as well.
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Magnesium is one of the most abundant minerals in soft tissue. The average adult body contains about 20 to 28 g of magnesium with about 60 per cent of this present in the bones, and the rest in the muscle, soft tissue and body fluids. Magnesium is found in high concentrations inside cells, particularly those of the brain and heart. Research into the role of magnesium is increasing in clinical importance as growing evidence suggests that magnesium deficiency may play a role in a number of disorders.
What it does in the body
Magnesium is a co-factor in over 300 enzyme reactions, particularly those involving the metabolism of food components and the formation of new compounds essential for good health. All enzymatic reactions requiring the energy storage molecule, adenosine triphosphate (ATP), require magnesium. It is also needed for protein synthesis, DNA manufacture, fatty acid synthesis, anaerobic breakdown of glucose; and the removal of toxic substances, such as ammonia, from the body.
Magnesium is vital for healthy bone structure.
Interaction with calcium
Calcium interacts with magnesium in many body processes, such as the regulation of blood vessel tone and contraction of muscles, including heart muscle. Calcium stimulates muscles and contracts blood vessels, while magnesium relaxes muscles and dilates blood vessels. Magnesium can contribute to calcium balance by affecting the hormones which control calcium absorption and metabolism, and also influences calcium at the cellular level by interacting with calcium transport mechanisms.
Magnesium is necessary for the action of a compound which plays a vital role in transmitting messages from hormones and other stimuli which cause chemical reactions inside cells. Magnesium also enhances insulin secretion, and helps it to move into cells, thus facilitating sugar metabolism.
Absorption and metabolism
Magnesium is mostly absorbed in the small intestine. In a normal person, around 50 per cent of dietary magnesium taken is absorbed. However, this depends on the concentration in the diet, with a lower percentage absorbed from a high magnesium diet. Magnesium absorption requires an acidic stomach environment. Absorption is reduced by laxative abuse, infections and allergies.
Foods low in protein or high in phosphorus can reduce magnesium absorption.
Oxalates, which are found in some green vegetables and phytates which are found in some grains, may form insoluble complexes with magnesium and prevent it from being absorbed. However, these foods are often high in magnesium which may compensate for the reduced absorption. Vitamin D promotes magnesium absorption. Some reports have suggested that magnesium and calcium compete for absorption but recent studies suggest that calcium does not affect magnesium absorption.1
The kidney is the main regulator of blood concentration and total body content of magnesium. Excretion mainly occurs at night. High protein and high sugar diets may increase magnesium excretion.
Magnesium deficiency affects all body tissues. Symptoms of severe deficiency, which is rare, include irritability, personality changes, anorexia, weakness, tiredness, vertigo, convulsions, nervousness, muscle cramps and tremors, tongue jerks and tremors, involuntary eye movements, unsteady gait, irregular heartbeat, palpitations, low blood sugar and sustained muscle contraction. Loss of hair, swollen gums, and damage to the arteries resembling atherosclerosis are symptoms of advanced deficiency. Magnesium deficiency leads to low blood calcium levels.
Deficiency can occur due to malnutrition, surgery, serious burns, kidney disease, pancreatic inflammation, liver disease, absorption disorders, diabetes, hormonal disorders, cancer, heavy exercise and pregnancy. A high dietary intake of phosphate, calcium, vitamin D and saturated fats may also lead to deficiency. Alcoholics and those taking diuretics are particularly at risk as these drugs both cause large urinary magnesium losses.
Marginal magnesium deficiency is considered to be very common and may affect 15 to 20 per cent of the population. It is common in those who eat diets high in processed foods, alcoholics, and in those with malabsorption problems.
Magnesium deficiency is especially prevalent in elderly people. This is due to low dietary intakes and also to the decreases in absorption and increases in excretion associated with aging.
Inadequate magnesium intake has been linked to several types of cardiovascular disease, including atherosclerosis, heart attack, angina, ischemic heart disease and cardiac arrhythmias. Epidemiological studies show that death rates from coronary heart disease are higher in areas where the water is low in magnesium. In a 1996 study, Swedish researchers investigated these links in 17 municipalities in the southern part of the country which had differing water magnesium concentrations. The study included 854 men who had died of heart attacks between the ages of 50 and 69, and 989 men of the same age in the same area who had died from cancer during the same time period. The results showed that men living in high magnesium water areas had a 35 per cent lower chance of death from heart attack than those who drank low magnesium water.2 The results of a 1997 study done in Taiwan suggest that magnesium in drinking water helps to prevent death from cerebrovascular disease.3
Results from the Atherosclerosis Risk in Communities (ARIC) Study support the association between low serum and dietary magnesium, and various types of cardiovascular disease including high blood pressure. A total of 15 248 people took part, male and female, black and white, aged 45 to 64 years. The results showed that serum magnesium levels were significantly lower in participants with cardiovascular disease, high blood pressure, and diabetes than in those free of these diseases. Low dietary intake was linked to lower beneficial HDL cholesterol levels and thicker carotid artery walls, both of which increase the risk of cardiovascular disease.4
Researchers involved in a 1996 study done in Wales found a trend towards protection from ischemic heart disease in men with high magnesium intakes. However, when other factors were taken into account, the results did not appear to be significant.5 Magnesium deficiency is also linked to variant angina, a disorder in which coronary heart vessels go into spasm.6 A 1996 Japanese study found that men with lower magnesium levels had more frequent and severe angina attacks.7 Magnesium-deficient heart muscle is more vulnerable to lack of oxygen.
Magnesium deficiency may increase the risk of cardiovascular disease in several ways. Chronic magnesium deficiency in animals has been shown to result in microscopic changes in the heart arteries and the development of atherosclerosis. Deficiency also leads to changes in the heart muscle itself, including cell degeneration, fibrosis, necrosis and calcification. Blood fat levels are also affected by magnesium dietary intake. Cholesterol may be more susceptible to oxidative damage when magnesium levels are low. Some of the harmful effects of magnesium deficiency may be due to the products of increased fat oxidation.
Magnesium deficiency also contributes to cardiac arrhythmias, possibly because magnesium is responsible for maintaining potassium concentrations inside muscle cells. Potassium plays a role in heart muscle contraction. Magnesium deficiency has been implicated in mitral valve prolapse, a disorder in which the mitral valve in the heart fails to properly close off the heart chambers from each other during contraction. As many as 85 per cent of sufferers may have chronic magnesium deficiency.
High blood pressure
Results from the ARIC study mentioned above showed that low dietary intakes of magnesium are linked to higher diastolic and systolic blood pressures, possibly due to a reduction in the relaxing effect on blood vessels and by indirect effects on potassium balance. Studies suggest that around 30 per cent of high blood pressure sufferers consume inadequate amounts of magnesium and high blood pressure is more common in areas where the water is low in magnesium.
The Honolulu Heart Study, which looked at the relationship between dietary magnesium intake and blood pressure, found that those in the high intake group had, on average, systolic blood pressures 6.4 mmHg lower and diastolic pressures 3.1 mmHg lower than those in the low intake group.8 In another survey of over 58 000 women, researchers found that those with magnesium intakes of less than 200 mg per day had a significantly higher risk of developing high blood pressure than women whose intakes were over 300 mg per day.9 In another study published in 1992, researchers also found that low dietary intakes of magnesium were linked to an increased risk of high blood pressure in over 30 000 men.10
Magnesium deficiency results in impaired insulin secretion and reduces tissue sensitivity to insulin. Sub-clinical magnesium deficiency is common in diabetes and occurs because of insufficient magnesium intakes and increased magnesium losses, particularly in the urine. In Type II, or non-insulin-dependent, diabetes mellitus, magnesium deficiency seems to be associated with insulin resistance. It may also be involved in the development of diabetes complications and may contribute to the increased risk of sudden death associated with diabetes. Some studies suggest that magnesium deficiency may play a role in spontaneous abortion and birth defects in diabetic women.
Results from the ARIC study suggest that serum magnesium levels are low in those suffering from diabetes and that intake is related to insulin levels. Magnesium plays a role in the insulin-mediated uptake of glucose into cells, and deficiency may worsen control of diabetes.11 Low blood magnesium levels are commonly associated with many complications of diabetes, including heart disease and high blood pressure.
According to research presented at the 1997 annual meeting of the American Diabetes Association, low magnesium levels predict Type II diabetes in whites. Researchers from Johns Hopkins University Medical School examined blood levels of magnesium in over 12 000 nondiabetic, middle-aged African American and white subjects and monitored them for six years. No relationship was found between magnesium levels and diabetes in African Americans, but a relationship was seen in whites.
Magnesium is vital for normal bone function and deficiency may contribute to osteoporosis. In a 1995 study, results showed that women whose dietary intakes were less than 187 mg per day had a lower bone mineral density than women whose average intakes were more than 187 mg.12
Magnesium is essential for the normal function of the parathyroid glands, metabolism of vitamin D, and adequate sensitivity of bone to parathyroid hormone and vitamin D. Magnesium deficiency may impair vitamin D metabolism which adversely affects bone-building.13 Magnesium deficiency is also known to cause resistance to parathyroid hormone action which affects calcium balance and may cause abnormal bone formation.14 However, magnesium excess inhibits parathyroid hormone secretion which means that bone metabolism is impaired under positive as well as under negative magnesium balance.15 Maintaining normal calcium-to-magnesium balance is very important in the prevention of osteoporosis.
Magnesium metabolism appears to be altered in some migraine sufferers and deficiency may contribute to symptoms through effects on neurotransmitters and blood vessels, and muscles in the head and neck.16
Red blood cell concentrations of magnesium appear to be low in women with premenstrual syndrome. The calcium to magnesium ratio also seems to be affected by hormonal fluctuations which may affect neurotransmitter levels and lead to premenstrual symptoms.17
Epidemiological evidence suggests that a low intake of magnesium is associated with impaired lung function, bronchial hyperreactivity and wheezing.
Magnesium deficiency leads to kidney stones in animal studies. Magnesium inhibits the precipitation of calcium phosphate and calcium oxalate, two substances which contribute to the formation of kidney stones.
Magnesium deficiency occurs early in the course of HIV infection. This may be relevant to the HIV-related symptoms of fatigue, lethargy and mental impairment.18
Lack of magnesium decreases energy efficiency, and research has shown that people who are deficient in magnesium may use more energy during exercise. In a recent study, USDA researchers investigated the amount of oxygen needed by healthy women over 50 to perform a certain amount of low intensity work on an exercise bicycle. When their dietary magnesium was inadequate (150 mg daily) they used 10 to15 per cent more oxygen to perform the work and their heart rates climbed by about 10 beats per minute. The results suggest that magnesium deficiency is associated with increased physiological demands to do the same amount of work as when magnesium is adequate.
In a 1998 study, researchers from the University of Texas examined body magnesium concentrations in 26 marathon runners during an endurance run. They found that levels in the muscles and urine dropped significantly, possibly putting the athletes at risk of decreased performance and muscle cramps.19
Magnesium deficiency may also play a role in pre-eclampsia and eclampsia (toxemia of pregnancy), leg cramps, sleeping problems, candida albicans infection, gastric cancer20, allergies, chronic fatigue syndrome and anxiety. Low blood levels of magnesium are also sometimes found in bulimia nervosa sufferers and patients with irritable bowel syndrome.
Good sources of magnesium include whole grains, nuts, soybeans, avocados, beans, corn, lemons and dark green leafy vegetables, as magnesium forms part of the green pigment, chlorophyll. Meat is rich in magnesium but it also contains calcium, phosphate and protein which reduce the amount of available magnesium. Flour refining, rice polishing, sugar extraction from molasses and other methods of food processing remove almost all the magnesium from these foods. Modern food production has reduced the average magnesium intake from 400 per day to 300 per day over the last 70 years.
Drinking water is an important source of magnesium, especially in hard water areas, and is usually better absorbed than magnesium from food.
|Cashew nuts||½ cup||169|
|Wheat bran||½ cup||168|
|Spinach, boiled||1 cup||148|
|Soybeans, cooked||1 cup||141|
|Baked beans||1 cup||105|
|Beet greens||1 cup||92.2|
|Black-eyed peas, cooked||1 cup||81.7|
|Brown rice, cooked||1 cup||79.8|
|Kidney beans, canned||1 cup||75.1|
|Chickpeas, cooked||1 cup||74.1|
|Artichokes, steamed||1 artichoke||72.0|
|Green peas||1 cup||58.9|
|Apricots, dried||1 cup||58.0|
|Oatmeal, cooked||1 cup||53.2|
|Wholewheat spaghetti, cooked||1 cup||39.9|
Recommended dietary allowances (RDA)
The RDAs for magnesium have recently been revised.
|USA (under 30)||400 mg||310 mg||-||-|
|USA (over 30)||420 mg||320 mg||-||-|
|USA (14 to 18)||-||-||400 mg||360 mg|
|USA (19 to 30)||-||-||350 mg||310 mg|
|USA (over 31)||-||-||360 mg||320 mg|
|UK||300 mg||270 mg||-||320 mg|
|Australia||320 mg||270 mg||300 mg||340 mg|
The tolerable upper intake limit is set at 350 mg for adults.
Magnesium requirements are increased during rapid growth in children and adolescents. The RDA for adolescent boys is 410 mg and for girls is 360 mg.
Studies have shown that most people may not get sufficient magnesium in their daily diets. Some research indicates that the RDAs for magnesium may be inadequate and that those who exercise may need up to 500 mg per day. Dr. Mildred Seelig, a well-known magnesium researcher, has recommended a daily intake of 6 to 10 mg per kg of body weight per day for optimal health.
Less than 1 per cent of the total body magnesium is present in blood. Thus, blood serum measurements of magnesium that are routinely made in a clinical setting assess only a small part of the total magnesium stores in the body and magnesium in the blood does not necessarily correlate with the amount of magnesium in other parts of the body. More sophisticated tests are not readily available in a clinical setting and even for these tests, results do not necessarily correlate with intracellular magnesium. Thus, there is no readily available test to determine intracellular/total body magnesium status. At present there is little information about the state of magnesium within body pools and deficiencies are difficult to pinpoint.
Magnesium supplements are available in a variety of forms, with varying amounts of magnesium. These include magnesium carbonate, magnesium amino acid chelates, magnesium citrate and dolomite. Organic forms of magnesium, such as citrate, aspartate and fumarate, are better absorbed than inorganic forms such as magnesium oxide and magnesium hydroxide, which is why the last two are often used as laxatives. Enteric-coated magnesium supplements may not be as well-absorbed as magnesium in other types of supplements.21
Magnesium supplements should not be taken with meals as they neutralize stomach acid. The suggested ratio of intake of calcium to magnesium is about two-to-one although one-to-one may be better. Magnesium supplements may be best taken at night. Alcoholics, people under stress or who exercise heavily, diabetics, anyone taking diuretic drugs (which deplete magnesium), and women who suffer from PMS or who take the contraceptive pill may benefit from supplements.
Toxic effects of excess intake
Magnesium toxicity is rare as the body excretes excess. Symptoms of toxicity include diarrhea, flushing of the skin, thirst, low blood pressure, loss of reflexes, lethargy, weakness, fluid retention, nausea, vomiting and shallow breathing. The most common cause of excess magnesium is renal failure.
Therapeutic uses of supplements
Low magnesium levels have been found in the blood and cardiac muscle of heart attack victims, and several small studies have shown that magnesium sulfate injections can reduce death rates in heart attack patients, both in the short term and for longer periods.22 It may act by improving energy production, inhibiting platelet aggregation, reducing vascular resistance, promoting clot breakdown, dilating blood vessels, and improving the function of heart muscle. It also protects the damaged heart muscle against calcium overload and reduces free radical damage.
However, two recently published studies showed different results, although similar doses of magnesium were used. The LIMIT-2-study was a double-blind, placebo-controlled investigation of over 2300 patients with suspected heart attack. Magnesium infusion reduced 28 day death risk by 24 per cent.23 The ISIS-4-study on over 50 000 patients with suspected heart attack did not show any positive effect of magnesium on death rate.24
However, in the ISIS-4 study, magnesium was given after the end of drug therapy to break down blood clots. In LIMIT-2, magnesium infusion was started as early as possible. It seems that in heart attack patients who have been given clot break-down drugs, magnesium therapy is not useful. These studies also suggest that timing of the magnesium treatment is important, and evidence suggests that the injections should be given early. Magnesium injections also show more beneficial effects in higher risk patients.
Magnesium is reasonably well-established as a therapy for certain types of cardiac arrhythmia. It is usually given intravenously.25 Post-operative administration can also reduce the incidence of arrhythmias following surgery. Magnesium may also enhance the action of digoxin, a drug often used to treat cardiac arrhythmia.
Magnesium supplements are often used to treat angina, both that caused by atherosclerosis and variant angina caused by coronary artery spasm. In a 1997 study, UK researchers assessed the effects of a 24-hour infusion of magnesium in patients with unstable angina. Thirty-one patients received magnesium sulfate and 31 placebo. After treatment, there were fewer ischemic episodes in the magnesium group, and duration of ischemia in the placebo group was longer than that in the magnesium group.26
Other heart conditions
Magnesium has also been used to treat cardiomyopathy, a weakening of heart muscle which leads to reduced efficiency of blood circulation and congestive heart failure. Sufferers of intermittent claudication, a painful condition caused by reduced blood flow to the legs, often have low magnesium levels and may be helped by supplements. Magnesium supplements have been successfully used to treat mitral valve prolapse.27 Magnesium supplements have been shown to reduce cholesterol and triglyceride levels.
High blood pressure
Magnesium supplements may be useful in the treatment of high blood pressure, although the results of studies have been mixed. Intravenous magnesium has been shown to reduce blood pressure, possibly by relaxing constricted blood vessels. Those with high sodium and low potassium levels and those taking diuretic drugs may benefit from magnesium supplements.
In a 1997 double-blind, placebo-controlled study carried out in Japan, 33 people received either a four-week treatment with oral magnesium supplementation ( 411 to 548 mg per day) or a placebo. The results showed that the systolic and diastolic blood pressure values decreased significantly in the magnesium group, but not in the placebo group. Measurements made during the study suggest that magnesium may lower blood pressure through its effects on the secretion of adrenal hormones which cause an increase in sodium excretion.28
In a 1994 study, 91 middle-aged and elderly women with mild to moderate hypertension who were not on antihypertensive medication were treated with either magnesium supplements or placebo for six months. At the end of the study, systolic blood pressure had fallen by 2.7 mm Hg and diastolic blood pressure by 3.4 mm Hg more in the magnesium group than in the placebo group.29
Magnesium supplements may be helpful in the treatment of kidney stones. In a 1997 study, researchers examined the use of potassium-magnesium citrate in the prevention of recurrent calcium oxalate kidney stones. Sixty-four patients received either a placebo or potassium-magnesium citrate daily for up to three years. The results showed that those in the supplement group had an 85 per cent lower risk of recurrence of stones.30 Mineral water containing high levels of calcium and magnesium may also be useful in preventing the formation of calcium oxalate kidney stones.31
Magnesium sulfate is routinely used in the USA to prevent convulsions in pre-eclampsia and to break down toxins in pre-term labor. A 1996 research review of trials of magnesium sulfate in the treatment of eclampsia and pre-eclampsia analyzed data from nine randomized trials involving 1743 women with eclampsia and 2390 with pre-eclampsia. The analysis showed that magnesium sulfate is effective in preventing the recurrence of seizures in eclampsia and in preventing them in pre-eclampsia.32
Researchers involved in a 1996 study reported in the Journal of the American Medical Association found that administration of magnesium sulfate to women before delivery reduced the risk of cerebral palsy in very low birthweight babies.33
A 1995 Swedish study showed that magnesium supplements may help reduce the pain and discomfort of night-time leg cramps that up to one-third of pregnant women suffer. Pregnant women tend to have lower blood magnesium levels than those who are not pregnant.34
Diabetics can benefit from magnesium supplements as they have been shown to improve glucose tolerance and insulin response and action. Magnesium may help protect against diabetic complications including heart disease and eye disorders.
In a 1994 study, Italian researchers investigated the effects of magnesium supplementation on glucose uptake and use in nine elderly Type II diabetic patients. Each patient was followed up for a period of three weeks before the study and was then given either a placebo or a magnesium supplement for four weeks. At the end of this time, improvements in insulin sensitivity and glucose oxidation were seen in those taking magnesium.35 Magnesium supplements have also been shown to lower blood pressure in Type II diabetics.36
Magnesium can act as a bronchial smooth muscle relaxant, and its use in the treatment of asthma is still in investigational stages. In a 1997 randomized, double-blind, placebo-controlled, cross-over study, 17 asthmatic people were given a low magnesium diet for two periods of three weeks, preceded and separated by a one week run-in/wash-out, in which they took either placebo or 400 mg magnesium per day. Asthma symptom scores were significantly lower during the magnesium treatment period.37 Intravenous magnesium has been successfully used as an emergency treatment for asthma in children.38 Magnesium sulfate aerosol has also been used effectively.39
Magnesium supplements may be beneficial in the treatment and prevention of migraine. In a 1996 study, Belgian researchers assessed the effect of oral magnesium on the prevention of migraine in 81 patients aged from 18 to 65. They were either given a placebo or a daily supplement of 600 mg for 12 weeks. In weeks nine to12, the attack-frequency was reduced by 42 per cent in the magnesium group and by 16 per cent in the placebo group. The number of days with migraine and the drug consumption for symptomatic treatment per patient also decreased significantly in the magnesium group.40 Supplements may also be useful in the treatment of menstrual migraine.41
Oral magnesium treatment has been shown to relieve menstrual and premenstrual symptoms including mood changes and breast tenderness. In a 1991 study, Italian researchers investigated the effects of a two-month period of magnesium supplementation on premenstrual symptoms in 32 women. The dose used was 360 mg three times a day, from the 15th day of the menstrual cycle to the onset of menstrual flow. The results showed that supplementation was effective in the treatment of premenstrual symptoms related to mood changes.42
Chronic fatigue syndrome
Magnesium sulfate injections have been shown to improve the symptoms of chronic fatigue syndrome.43 Further research is need to determine if oral supplements can show the same effects.
Supplements may help to increase bone mineral density in postmenopausal women, thus reducing the risk of osteoporosis. In a 1990 study, US researchers investigated the effect of a dietary program emphasizing magnesium instead of calcium for the management of postmenopausal osteoporosis. Nineteen women on hormonal replacement therapy (HRT) received 500 mg magnesium and 600 mg calcium, and seven other women on HRT did not receive supplements. The results showed that in one year, those women given the supplements had greater increases in bone mineral density than those who were not. Fifteen of the 19 women had had bone mineral density below the spine fracture threshold before treatment; within one year, only seven of them still had values below that threshold.44
In a 1993 study, Israeli researchers assessed the effects of supplemental magnesium in 31 postmenopausal women who received six 125 mg tablets daily for six months and two tablets for another 18 months in a two-year trial. Twenty-three symptom-free postmenopausal women were assessed as controls. The results showed that 22 patients responded with a 1 to 8 per cent rise of bone density. The mean bone density of all treated patients increased significantly after one year and remained unchanged after two years. In control patients, the mean bone density decreased significantly.45
Supplements have also been used in the treatment of epilepsy, glaucoma, attention deficit hyperactivity disorder (ADHD), hearing loss, thalassemia, irritable bowel disorders and alcoholism. Taken with calcium they may have neuromuscular relaxing effects and may be useful in insomnia. Some antacids contain magnesium bound to an alkali that neutralizes stomach acid. It is also used as a laxative (in milk of magnesia) as it draws fluid into the bowel.
Interactions with other nutrients
High doses of zinc decrease magnesium absorption. Magnesium is necessary for thiamin, vitamin C and pyridoxine metabolism. Calcium, sodium, phosphorus and potassium metabolism are linked to magnesium metabolism in bone formation, muscle contraction and nerve transmission. High calcium intake may lead to magnesium deficiency. Magnesium deficiency may be linked to potassium deficiency and supplementation reduces potassium loss. Excess vitamin D may lead to magnesium deficiency.
Interactions with drugs
Antibiotics, antidepressants, estrogen and heart drugs can all affect magnesium levels. Diuretics are a major cause of magnesium deficiency. Magnesium salts may decrease the absorption of other drugs taken at the same time such as digoxin, tetracycline, iron and phenytoin.
People with kidney problems and some heart diseases should not take large doses of magnesium.
SOURCE of information comes from: http://www.vitamin-update.com/definition.cfm/id/33.html