• Building bones
• Creating proteins for use in the body
• Conduction of nerve impulses
• Adjusting to cold

Deficiency usually occurs among people with excessive diarrhea, kidney disease, diabetes, a history of alcohol abuse, and those taking diuretics.

Signs of magnesium deficiency:

• Muscle twitching/tremors
• Abnormal heartbeat
• Insomnia
• Muscle fatigue
• Cramps

Too much magnesium causes disturbed nervous system functions due to an imbalance between calcium and magnesium in the system. Excessive amounts of magnesium are especially dangerous for people with bad kidneys.

References:

• National Research Council. Recommended Dietary Allowances, 10th Edition. Washington: 1989.
• Brody, Jane. Jane Brody's Nutrition Book. Bantam Books. 1987.