Magnesium is an essential mineral vital to maintaining normal cardiac rhythm, bone health, regulating blood pressure and blood sugar levels, energy metabolism, protein synthesis and healthy muscle, nerve and immune function. Halibut, nuts, legumes, whole grains and spinach are all sources of magnesium, but a significant number of people in the U.S., especially older Americans and African-Americans, don't consume enough dietary magnesium, according to the National Institutes of Health Office of Dietary Supplements. Magnesium supplements can provide a healthy addition to dietary magnesium, but there are risks associated with supplemental magnesium.
Hypermagnesemia
Dietary magnesium poses no health risk, but large doses of supplemental magnesium can cause hypermagnesemia, or dangerously high blood magnesium levels. The kidneys help regulate blood magnesium levels, excreting magnesium from the body when levels rise, but underlying kidney disease can reduce the organs' ability to excrete magnesium, making the risk of hypermagnesemia higher in those with reduced kidney function. Symptoms of hypermagnesemia include nausea, anorexia, diarrhea, abdominal cramping, muscle weakness, difficulty breathing, hypotension and changes in mental status. Acute hypermagnesemia can lead to cardiac arrest, coma and death. Excessive consumption of magnesium-containing laxatives and antacids can also cause hypermagnesemia. The University of Alabama at Birmingham's Department of Pediatrics also documented a case of fatal hypermagnesemia in a 7-year-old boy caused by the administration of an Epsom salt enema.
Drug Interactions
Magnesium bonds with tetracycline, an antibiotic commonly used to treat respiratory, urinary and genital infections, gastric ulcers and Lyme disease and as a post-exposure prophylactic against anthrax. When magnesium bonds to tetracycline, it reduces the body's ability to absorb tetracycline, which will reduce the antibiotic's effect. Inform your physician if you are taking magnesium supplements.
Dosing
The recommended dietary intake of magnesium varies by age and gender. Adult women ages 19 to 30 should consume approximately 310mg per day, and those over age 30 should consume 320mg per day. Male adults ages 19 to 30 should consume 400mg per day, and those over 30 should consume 420mg per day. The tolerable upper intake level of magnesium, or the maximum amount of supplemental magnesium it is safe to consume per day, is 350mg for adults, including pregnant and lactating women. It should be noted that this number refers solely to supplemental magnesium. There is no tolerable upper intake level set for dietary magnesium.
References
- National Institutes of Health Office of Dietary Supplements: Magnesium
- National Center for Biotechnology Information: Acute Hypermagnesemia After Laxative Use
- National Center for Biotechnology Information: Fatal Hypermagnesemia Caused by an Epsom Salt Enema: A Case Illustration
- Medline Plus: Tetracycline
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