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Magnesium

Magnesium

Description

Magnesium is an important component of every cell of the body. Magnesium is an essential part of many enzyme systems, including the production and transfer of energy for protein synthesis and contraction of muscles.

Magnesium is also required for proper nerve function, activation of most of the vitamin B-complex vitamins, and synthesis of many compounds.

Magnesium and cardiovascular disease
A number of studies have demonstrated a relationship between a wide variety of cardiovascular diseases and magnesium deficiency. The following observations appear to support this association:

1. An increased prevalence of cardiovascular disease in geographic areas having soft water, which has low levels of magnesium and calcium.

2. Significantly decreased cardiac levels of magnesium in victims of sudden death due to heart attack, as compared with victims of sudden death due to acute trauma.

3. Until relatively recently, it was generally believed low serum magnesium levels in individuals were rare. Recent evidence from hospital studies indicates in hospitalized patients, the overall incidence of low magnesium levels can range from 7 to 52%. Compounding this data is the fact that serum magnesium levels may not accurately represent tissue magnesium levels since magnesium is found largely within cells and not in serum.

4. Clinical trials have demonstrated magnesium supplementation (usually intravenously) successfully influences a variety of cardiovascular diseases including: acute heart attack, cardiac arrythmias, mitral valve prolapse, digitalis toxicity, diabetic angiopathy, transient ischemic attacks, hypertension and classical migraine.

Absorption
The percentage of ingested magnesium actually absorbed ranges from 24 to 85%. A number of physiological factors will reduce magnesium absorption: increased magnesium intake; malabsorption or chronic diarrhea; and increased amounts of calcium, phosphate, fat and phytates in the diet.

Magnesium does not require vitamin D for absorption, yet it does compete for absorption with calcium. As calcium intake is increased, magnesium absorption is decreased and vice versa.

Method of Action

Magnesium's mechanism of action largely relates to its involvement as a cofactor in a wide variety of enzyme systems. Free cellular magnesium affects cell energy production, the action of various hormones on target cells, protein synthesis and cellular electrolyte content.

Magnesium enters the cell by a process of facilitated diffusion requiring a transporter.

Properties & Uses

Various gastrointestinal disorders, such as diarrhea and vomiting, as well as malabsorption, may result from magnesium deficiencies. Magnesium supplements can be used in conjunction with rehydration therapy as a preventative measure against the neuromuscular irritability (e.g., tremor and spasms) which can result from low serum magnesium.

Magnesium is useful and essential in the treatment of malnutrition in preventing a tetany-like reaction, and in curtailing nervous symptoms brought on by magnesium deficiencies. Burn victims frequently have excessive losses of magnesium and supplementation may be advisable.

Magnesium is useful in protection against heart muscle disease and, in conjunction with vitamin B-6, aids in the removal of kidney stones.

Magnesium is among the trace minerals and vitamins used in experimental treatment of autistic behavior.

Consequence of Deficiency

Severe deficiency of magnesium is characterized by anorexia, growth failure, cardiac abnormalities neuromuscular, disorders including tetany, depression, muscular weakness, dizziness and sensitivity to the environment.

Conditions in which acute deficiency may develop include:

Persistent vomiting
Intestinal malabsorption
Kidney disease
Diuretic therapy
Hyperthyroidism
Acute alcoholism
Diabetes
Parathyroid gland disease
After surgery

A less severe magnesium deficiency may be an important causative factor in many conditions, including:

Kidney stones
Myocardial infarction
Angina
Cardiac abnormalities
Diabetic complications
Premenstrual syndrome (PMS)

Toxicity Factors

Excessive intake of magnesium salts, like magnesium sulfate, can result in significant diarrhea. Excess intake of magnesium could also result in decreased calcium absorption.

Magnesium toxicity is extremely rare in individuals with normal kidney function. However, in patients with kidney failure, magnesium toxicity can be a significant problem.

Recommended Dietary Allowance

ageRDA (mg)RNI (mg)
infants/children
0-3 months 40 55
4-6 months 40 60
7-9 months 60 75
10-12 months 60 80
1-3 yeares 80 85
4-6 years 120 120
7-10 years 170 200
males
11-14 years 270 280
15-18 years 400 300
19+ years 350 300
females
11-14 years 280 280
15-18 years 300 300
19+ years 280 270
pregnancy 320 -
lactation(1st 6 month) 355 320
(2nd 6 month) 340 320



For over thirty years, Recommended Daily Amounts has existed in the United Kingdom. It has been used to measure the adequacy of an individual's diet. However, in 1991 the Committee on Medical Aspects of Food Policy (COMA) gave forth a whole new set of figures upon the request of the Department of Health's Chief Medical Officer. Reference Nutrient Intake (RNI) is one of these sets collectively known as "Dietary Reference Values." RNI is an amount of a nutrient that is enough for almost every individuals, even someone who has high needs for the nutrient. This level of intake is, therefore, considerably higher than what most people would need. If individuals are consuming the RNI of a nutrient they are most unlikely to be deficient in that nutrient.

Excess intake of magnesium could result in diarrhea or decreased calcium absorption. Magnesium toxicity is extremely rare in individuals with normal kidney function. However, in patients with kidney failure, magnesium toxicity can be a significant problem.

Food Sources

Beans (dried)Bone meal
Brown sugarCereals
EggGreen pea
Hot cocoaMilk
NutsOrange juice
Peanut butterPotato
SeafoodsSoybean
TomatoTuna
Whole wheat



Abstracts

References

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