DEFICIENCY

Magnesium deficiency

Experimentally induced in humans by dietary restriction:

• Neuromuscular changes
• Personality changes
• Anorexia
• Nausea and vomiting
• Cardiovascular: ECG changes, arrhythmia
• Low levels of Mg, K, Ca in blood

Risk factors for Mg depletion:

• Gastrointestinal disorders
• Renal dysfunction (excessive urine losses)
• Endocrine disorders (various – esp. diabetes mellitus)
• Paediatric disorders (various – genetic, congenital, infectious)
• Alcoholism; burns, trauma (esp. when fluids administered are low in Mg); post-cardiac or transplantation surgery

With so many possible causes, deficiency is likely to be quite common in acutely or chronically ill patients.

Mg and coronary artery disease

Some studies have claimed an inverse association between coronary artery disease incidence and consumption of ’hard’ water (containing Ca, Mg, phosphates, etc.) Other studies found no clear association.

Depressed Mg status was implicated as a cause of dysrhythmias and myocardial infarction (MI); but the evidence was mostly from uncontrolled observations of low Mg in patients after admission.

Trials of intravenous Mg in MI patients:

• Leicester Intravenous Mg Intervention Trial (LIMIT-2); decrease in mortality.

• 4th International Study of Infarct Survival (ISIS-4); no decrease in mortality, and a significant increase in deaths in heart failure patients and those suffering from cardiogenic shock.

-→ debate continues.

Mg and cancer

Early epidemiological studies: higher incidences of neoplasms and lymphoproliferative disorders in regions with low Mg in soil and water.

More recent case-control study in Taiwan: high levels of Mg in drinking water protect against gastric cancer.