Although little heralded, magnesium may be one of the most important minerals for good health.

Studies suggest that, besides enhancing some 300 enzyme-related processes in the body, magnesium may help to prevent or combat many chronic diseases.


What it is

The average person’s body contains just 28 grams of magnesium, but this small amount is vital to a number of bodily functions. Many people do not have adequate stores of magnesium, often because they consume processed foods, which contain very little of this mineral.

Magnesium levels are easily depleted by stress, by certain diseases or medications, and by intense physical activity. For this reason, nutritional supplements may be necessary for optimal health.

They are available in several forms, including magnesium aspartate, magnesium carbonate, magnesium diglycinate, magnesium gluconate and magnesium oxide. Magnesium sulphate (Epsom salts) is a well-known laxative.


What it Does

Magnesium is involved in energy production, nerve function, muscle relaxation, and bone and tooth formation.

In conjunction with calcium and potassium, magnesium regulates heart rhythm; it also plays a role in the production and use of insulin.



Recent studies indicates that magnesium helps to prevent and treat heart disease. Studies show that the risk of dying of a heart attack is lower in areas with ‘hard’ water, which contains high levels of magnesium.

Some researchers speculate that, if everyone drank hard water, the number of deaths from heart attacks might decline by 19%. Magnesium appears to lower blood pressure, and has also been found to aid recovery after a heart attack by inhibiting blood clots, widening arteries and normalising dangerous arrhythmias.

Preliminary studies suggest that an adequate intake of magnesium may prevent non-insulin-dependent (type 2) diabetes. Researchers at Johns Hopkins University in Baltimore measured magnesium levels in more than 12 000 people who did not have diabetes and tracked them for six years to see who developed the disease.

Those with the lowest magnesium levels had a 94% greater chance of developing the disease than those with the highest levels. (These results apply only to Caucasians.

Magnesium levels don’t seem to affect diabetes in African-americans, while other groups have not been studied.) More research is needed to see if magnesium supplements can prevent the disease.


Additional benefits

Because magnesium relaxes muscles, it’s useful for sports injuries and fibromyalgia. It also seems to ease PMS and menstrual cramps, and may increase bone density in postmenopausal women, helping to prevent or delay the onset of osteoporosis.

In addition, magnesium expands the airways, which is helpful in treating asthma and bronchitis. Studies are inconclusive about magnesium’s rolein preventing or treating migraines, but one study suggests that it may enhance the effect of sumatriptan, a prescription drug used for migraines.

Common uses

  • Reduces spasms and cramps.
  • Helps to protect against heart disease and irregular heartbeat (arrhythmia).
  • Eases fibromyalgia symptoms.
  • Lowers high blood pressure.
  • May reduce the severity of asthma attacks.
  • Improves symptoms of premenstrual syndrme (PMS).
  • Helps to prevent the complications of diabetes.


  • Capsule.
  • Tablet.
  • Powder.


How much you need

The RDI for magnesium is 320 mg for men and 270 mg for women daily. Higher doses are required to prevent or treat specific diseases, as well as for women who take oral contraceptives.

If you get too little: Even moderate deficiencies can raise the risk of heart disease and diabetes. Severe deficiencies can results in irregular heartbeat, fatigue, muscle spasms, irritability, nervousnes and confusion.

If you get too much: Magnesium (particularly as Epsom salts) may cause diarrhoea and nausea. More serious side effects – muscle weakness, lethargy, confusion and difficulty breathing – can develop if the body can’t process high doses. But overdosing on magnesium is rare because the kidneys are usually efficient at eliminating excess amounts.


How to take it


To prevent heart disease: Take 400 mg a day. For arrthymias, congestive heart failure and asthma: Take 400 mg twice a day. For fibromyalgia: take 150 mg of magnesium with 600 mg of malic acid twice a day. For high blood pressure: Try 500 mg a day. For diabetes: Take 500 mg daily.

Guidelines for use

Magnesium is best absorbed when taken with each meal. If supplements cause diarrhoea, lower the dose or use magnesium diglycinate or gluconate, which are easier on the digestive tract.

Other sources

Good food sources of magnesium are whole grains, nuts, legumes, dark green leafy vegetables and shellfish.


  • People with kidney disease should consult their physicians before taking magnesium.
  • Magnesium can make tetra-cycline antibiotics less effective. Consult your doctor.
  • Reminder: If you have a medical condition, talk to your doctor before taking supplements.