Ninety-nine percent of the body’s magnesium is contained within its cells: about 60% in the bones, 20% in the muscles, 19%–20% in the soft tissue, and 1% circulates in the blood.
Important to both nutrition and medicine, magnesium, like calcium and phosphorus, is considered a major mineral. Magnesium in its carbonate and sulfate forms has been used for centuries as a laxative. The name of the element comes from Magnesia, a city in Greece where large deposits of magnesium carbonate were discovered in ancient times.
Magnesium is an important element in the body because it activates or is involved in many basic processes or functions, including:
- cofactor for over 300 enzymes
- oxidation of fatty acids
- activation of amino acids
- synthesis and breakdown of DNA
- immune function
- interactions with other nutrients, including potassium, vitamin B6, and boron
Magnesium has a number of general uses, primarily in standard allopathic medicine, but also in some alternative therapies.
The ULs apply only to magnesium taken as a dietary supplement or given for medical reasons, since no toxicity from magnesium occurring naturally in foods has been reported. The ULs for magnesium are: 1–3 years, 65 mg; 4–8 years, 110 mg; 9 years and over, 350 mg.
Good dietary sources of magnesium include nuts; dried peas and beans; whole grain cereals such as oatmeal, millet, and brown rice; dark green vegetables; bone meal; blackstrap molasses; brewer’s yeast; and soy products.
Dark green vegetables are important sources of magnesium because it is the central atom in the structure of chlorophyll. Drinking hard water or mineral water can also add magnesium to the diet.
A severe magnesium deficiency in a healthy person is unusual because normal kidneys are very efficient in keeping magnesium levels balanced.
This condition, called hypomagnesemia, is usually caused either by disease (kidney disease, severe malabsorption, chronic diarrhea, hyperparathyroidism, or chronic alcoholism) or as a side effect of certain medications, most commonly diuretics, cisplatin (a cancer medication), and a few antibiotics.
The symptoms of hypomagnesemia include disturbances of the heart rhythm, muscle tremors or twitches, seizures, hyperactive reflexes, and occasional personality changes (depression or agitation).
A patient with hypomagnesemia may also produce Chvostek’s sign, which is a facial spasm caused when the doctor taps gently over the facial nerve. This condition of painful intermittent muscle contractions and spasms is known as tetany. Hypomagnesemia can be treated with either oral or intravenous preparations containing magnesium.
Magnesium toxicity (hypermagnesemia) is rare because excessive amounts are usually excreted in the urine and feces. Most cases of hypermagnesemia are caused by overuse of dietary supplements containing magnesium.
The symptoms of magnesium toxicity include central nervous system depression, muscle weakness, fatigue, and sleepiness. In extreme cases, hypermagnesemia can cause death. It can be treated with intravenous calcium gluconate along with respiratory support. Severe hypermagnesemia can be treated by hemodialysis or peritoneal dialysis.
Standard medical practice
A low blood level of magnesium may indicate hypomagnesemia. Because 99% of the body’s magnesium is contained in its cells, blood tests can only measure the approximately 1% of magnesium that is extra-cellular (circulating in the bloodstream). This makes it difficult to diagnose low magenesium levels.
Fortunately, magnesium levels in urine can also aid diagnosis. High levels of urinary magnesium may indicate overconsumption of supplemental magnesium, overuse of diuretics, hypercalcemia (too much calcium in the body), hypophosphatemia (too little phosphate in the body), or metabolic acidosis (high blood acid levels).
Low levels of magnesium in the urine may point to hypomagnesemia or hypocalcemia (too little magnesium or calcium in the body), an underactive parathyroid gland, or metabolic alkalosis (high blood alkaline levels).
TREATMENT. Magnesium is used to treat tachycardia (excessively rapid heartbeat) and low levels of electrolytes (chloride, potassium, and sodium). It helps manage premature labor, and can be given prophylactically to prevent seizures in toxemia of pregnancy.
In 2002, a major international study verified the effectiveness of magnesium sulfate in preventing eclampsia, a potentially fatal seizure condition in pregnant women. Not only is it effective, but at a cost of about $5 per patient, it proves less expensive as well.
Magnesium helps control seizures resulting from hypomagnesemia associated with alcoholism, Crohn’s disease, or hyperthyroidism. Magnesium injections are also used to treat acute asthma attacks.
Magnesium preparations may be given as antacids in the treatment of peptic ulcers and hyperacidity. They are also given as laxatives for the short-term relief of constipation or to empty the patient’s bowel prior to surgery or certain diagnostic procedures. Magnesium hydroxide is used to treat patients who have been poisoned by mineral acids or arsenic.
Magnesium in the form of magnesium sulfate is known as Epsom salts. It can be taken by mouth as a laxative, but is also used externally to reduce tissue swelling, inflammation, and itching from insect bites, heat rash, or other minor skin irritations. Epsom salts can be applied to the affected skin or body part in moist compresses, or dissolved in warm bath water.
Recent research indicates that magnesium deficiency may contribute to atherosclerosis (hardening of the arteries), as well as to necrotizing enterocolitis (NEC), a sometimes-deadly inflammation that destroys the bowel in premature infants. Magnesium may also be useful in treating attention-deficit hyperactivity disorder (ADHD) and migraine headaches. Alternative medicine
HOMEOPATHY. Phosphate of magnesia is a staple homeopathic remedy, called Magnesia phosphorica (Mag. phos.) It is recommended for symptoms that are relieved by the application of warmth and gentle pressure, such as hiccups accompanied by colic in infants, menstrual cramps that are relieved when the woman bends forward, and abdominal pain without nausea and vomiting. Patients who benefit from Mag. phos. are supposedly less irritable or angry in temperament than those who need Colocynthis or Chamomilla.
NATUROPATHY. Naturopaths emphasize the importance of proper food selection and preparation to obtain an adequate supply of nutrients in the diet. They maintain that modern methods of agriculture promote overcropping and soil depletion, which they believe reduces the amount of magnesium (and other minerals) available from food grown in that soil.
The processing and refining of wheat and rice, which discards the magnesium contained in the bran, wheat germ, or rice husks, also reduces the amount of magnesium in these foods.
For these reasons naturopaths often recommend organic produce, which they believe contains higher levels of minerals, and suggest that they not be overcooked or boiled in too much water. In addition, this water, or “pot liquor,” is often rich in magnesium that cooks out of the vegetables. It should not be discarded but saved for use in soups or stews.
Many naturopaths believe that the official government recommended daily allowance (RDA) of magnesium is too low. They think that it should be doubled to about 600 or 700 mg daily for adults. Most recommend the use of dietary supplements containing magnesium to make up the difference.
Naturopathic practitioners regard magnesium to be important in the relief or cure of the following conditions:
- Mitral valve prolapse: Magnesium deficiency may lower the body’s ability to repair defective connective tissue, including defective mitral valves.
- Certain psychological conditions, including apathy, decreased ability to learn, memory loss, and confusion.
- Kidney stones: Magnesium increases the solubility of certain calcium compounds that form kidney stones if they are not excreted in the urine.
- Hypertension: Hypertensive people often have lower levels of magnesium within their cells than people with normal blood pressure.
- Angina pectoris: Magnesium is thought to relax spastic arteries and help prevent arrhythmias.
- Osteoporosis: Many osteoporosis patients have low levels of magnesium in their bodies.
- Premenstrual syndrome (PMS) and menstrual cramps: Some women report relief from the symptoms of PMS when taking magnesium supplements.
- Naturopaths also treat asthma, epilepsy, autism,hyperactivity, chronic fatigue syndrome, noise-induced hearing loss, insomnia, and stress-related anxiety with supplemental magnesium.
Naturopaths generally recommend supplemental magnesium for people with high blood cholesterol, postmenopausal women, women taking birth control pills, diabetics, people who eat a lot of fast food or other highly processed food, and people who drink alcohol.
Many nutrition experts recommend supplements that contain a balanced ratio of calcium to magnesium, usually two parts of calcium to one of magnesium. People who increase their calcium intake should increase their dose of magnesium (and phosphate) as well, because they work together and complement each other.
Some naturopaths recommend taking magnesium in the form of an aspartate or a citrate, arguing that these compounds are more easily absorbed by the body than magnesium carbonate or magnesium oxide. Others prefer magnesium chelated (combined with a metallic ion) with amino acids. Magnesium can also be obtained from herbal sources, such as red raspberries.
Standard medical preparations
Magnesium hydroxide is a common over-the-counter antacid, available as either a tablet or liquid. Most antacid tablets contain about 200 mg of magnesium hydroxide; liquid magnesium hydroxide is sometimes called milk of magnesia.
Magnesium carbonate works as a cathartic or laxative when combined with citric acid to produce magnesium citrate; it is often flavored with lemon or cherry to make it more pleasant to swallow.
Magnesium sulfate (in the form of Epsom salts) is available over the counter, usually in half-pound or pound boxes. Epsom salts are small whitish or colorless crystals that dissolve easily in water and have a bitter or salty taste.
Magnesium for intravenous dosage is prepared as a sulfate in a 50% solution. In general, intravenous administration of magnesium is reserved for patients with such serious symptoms as seizures, preeclampsia or eclampsia of pregnancy, acute asthma attacks, or severe cardiac arrhythmias. Magnesium sulfate can also be given by intramuscular injection.
Preparations containing magnesium should not be given as laxatives to patients with kidney disease, nausea and vomiting, diarrhea, abdominal pain, rectal bleeding, symptoms of appendicitis, or symptoms of intestinal obstruction or perforation.
In addition, these preparations should not be used routinely to relieve constipation, as the patient may become dehydrated, lose calcium from the body, or develop a dependence on them. Antacids containing magnesium should be used with caution in patients with kidney disease.
Magnesium preparations taken internally may cause hypermagnesemia, especially with prolonged use; electrolyte imbalance; and abdominal cramps when taken as a laxative. Milk of magnesia occasionally produces nausea or diarrhea. There are no known side effects of Epsom salts when used externally.
Milk of magnesia will decrease the patient’s absorption of chlordiazepoxide, digoxin, isoniazid, quinolones, or tetracycline antibiotics. Because it increases the gastrointestinal tract’s mobility, magnesium can also decrease the absorption (and thereby the effectiveness) of many other drugs and supplements as well.
Magnesium sulfate, if given intravenously, is incompatible with calcium gluceptate, clindamycin, dobutamine, polymyxin B sulfate, procaine, and sodium bicarbonate.