How Much Magnesium Is Harmful?

Sep 11, 2011 | By Vanessa Newman

Your bones store magnesium. At any time you have 10 g to 14 g of magnesium in your bones, and another 10 g to 14 g used for other purposes. Magnesium is a mineral required by your body for properly-functioning muscles, a healthy cardiovascular and nervous system and even good mental health. While it is difficult to become deficient, certain medications , bulimia and stress can deplete this vital mineral. Always check with your doctor before supplementation with a mineral for proper doses and interaction information.

Optimal Daily Intake

For every mineral, a recommended intake has been set. The recommended dietary allowance set by the Institute of Medicine of the National Academy of Sciences is 310 milligrams for adult women and 400 milligrams for adult males each day. Both men and women should get 500 mg to 750 mg of magnesium daily for best health, according to the authors of “The Real Vitamin & Mineral Book.” If you choose to supplement for certain conditions like fibromyalgia or osteoporosis, up to 1,000 milligrams is advised.

Toxicity

Magnesium from food, supplementation or products like Epsom salts or antacids should be below 9,000 milligrams daily. Getting this amount or above could be toxic for you, and trigger abdominal cramps, diarrhea and stomach upset with toxicity. If you have kidney disease, you're more susceptible to magnesium toxicity if supplementation with the mineral is not used with care.

Hypermagnesemia

Improper use of antacids or milk of magnesia can create magnesium toxicity. With severe elevations of magnesium in the bloodstream, called hypermagnesemia, other symptoms such as loss of muscle reflexes, breathing problems, irregular heartbeat and dangerously low blood pressure can occur. In one documented case reported by the Office of Dietary Supplements, an adolescent girl developed hypermagnesemia from taking antacids every 2 hours over a 24-hour period.

Magnesium and Kidney Disease

For those with kidney disease, magnesium in the form of antacids and milk of magnesia must not be taken at all. Magnesium supplementation is also prohibited for people with renal disease due to the potential for harm. The kidneys cannot properly process the mineral magnesium.