Magnesium

Chief functions

• Is needed for more than 300 biochemical reactions in the body
• Helps maintain normal muscle and nerve function
• Keeps heart rhythm steady
• Supports a healthy immune system
• Keeps bones strong
• Helps regulate blood sugar
• Promotes normal blood pressure
• Is involved in energy metabolism and protein synthesis

Possible benefits

• Possible role in preventing and managing diseases, such as:
  • Hypertension
  • Cardiovascular disease
  • Diabetes
  • Osteoporosis

Deficiency symptoms

• Loss of appetite
• Nausea and vomiting
• Fatigue and weakness
• Numbness and tingling
• Muscle contractions and cramps
• Seizures
• Personality changes
• Abnormal heart rhythms
• Coronary spasms

Toxicity symptoms

• Diarrhea
• Abdominal cramping
• Risk of toxicity increases with increasing kidney failure

Nutrient-nutrient reactions and absorption

• Absorbed in the small intestines
• Approximately one third to one half of dietary magnesium is absorbed into the body
• Severe magnesium deficiency can result in low levels of calcium in the blood
• Magnesium deficiency also is associated with low levels of potassium in the blood

DRI=Dietary Reference Intakes
mg=milligram
ND=not determined

Tolerable upper limits are not defined at certain ages, because of a lack of data on adverse effects. The upper limits for magnesium apply to synthetic forms obtained from drugs or supplements only.

Dietary sources

• Best—green vegetables, such as spinach
• Good—legumes, nuts, seeds, and whole unrefined grains

Groups at highest risk for deficiency

• Patients with gastrointestinal disorders such as Crohn’s disease, which can limit the body’s ability to absorb magnesium
• Persons with chronic or excessive vomiting and/or diarrhea
• Individuals taking certain medications, including certain diuretics, antibiotics, and cancer medications
• People abusing alcohol
• Older adults

Other facts

• Fourth most abundant mineral in the body
• Approximately 50% of magnesium is found in the bone; the other half is found predominately inside cells of body tissues and organs
• Only 1% of magnesium is found in the blood
• Excreted through the kidneys

References
Sizer F, Whitney E. Nutrition Concepts and Controversies. 11th ed. Belmont, CA: Thomson & Wadsworth; 2008:219-259.

Somer E. The Essential Guide to Vitamins and Minerals. New York, NY: Harper Collins Publishers; 1992:1-65, 224-246, 287-293.

Schlenker E, Long S. Essentials of Nutrition and Diet Therapy. 9th ed. St Louis, MO: Mosby Elsevier; 2007:107-144.

National Academy of Sciences, Institute of Medicine, Food and Nutrition Board. Dietary Reference Intakes: recommended intakes for individuals. Available at: http://fnic.nal.usda.gov/nal_display/index.php?info_center=4&tax_level=3&tax_subject=256&topic_id=1342&level3_id=5140. Accessed July 28, 2008.

National Institutes of Health, Office of Dietary Supplements. Magnesium. Available at: http://ods.od.nih.gov/factsheets/magnesium.asp. Accessed August 26, 2008.

Review Date 10/08
G-0801