Magnesium

What is magnesium and what does it do?

Magnesium is a mineral that is required by every cell of your body. At least half of the magnesium in your body is found in combination with calcium and phosphorus in your bones. The other half of your body's magnesium stores are found inside cells of body tissues and organs. About 1% of the magnesium in your body is found in your blood. Magnesium is needed for more than 300 biochemical actions in your body that control muscle contraction, nerve function, heartbeat, energy production, and protein synthesis.

How does magnesium affect bone mass and the risk for osteoporosis?

Further research is needed to better understand the role that magnesium plays in calcium metabolism, its effect on bone mass, osteoporosis, and fracture risk. Although some population studies suggest that dietary magnesium deficiency may be a risk factor for osteoporosis, more studies are needed to prove it.

How much magnesium is recommended each day?

The Recommended Dietary Allowance (RDA) is 420mg per day for healthy men and 320 mg per day for healthy women.

What are the best sources of magnesium in the diet?

Magnesium is widely available in a wholesome diet that includes beans, nuts, seeds, legumes, fish (halibut, flounder and sole), a variety of vegetables (spinach, artichoke and okra to name a few), and unprocessed grains. The processing of grains results in the removal of the bran and germ, both of which are high in magnesium content. To get more magnesium in your diet, it is wise to select fewer refined grains. For example, it is best to choose bran or oat bran cereals instead of refined cereals and brown rice instead of white rice. For more magnesium and fiber, it is recommended to select breads listing whole wheat flour as the first ingredient on the food label. To sweeten things a bit, dark chocolate is high in magnesium, too! Eating a wide variety of foods helps to ensure an adequate intake of magnesium. 

For more information about the magnesium content of selected foods, click on the USDA National Nutient Database listed according to magnesium content or listed alphabetically.

Do most people get enough magnesium?

Dietary surveys suggest that most adult men and women in the United States do not get the recommended amounts of magnesium. Individuals over age 70 appear to have the lowest magnesium intake of any adult group.

Is magnesium deficiency common?

Even though dietary surveys suggest that the typical American diet is low in magnesium, magnesium deficiency is rare. When magnesium deficiency does occur, it is seen in individuals with conditions or diseases in which the body does not handle magnesium normally. This may include:

• Individuals with gastrointestinal diseases that cause poor absorption or increased losses of magnesium related to chronic diarrhea and/or vomiting
• Individuals taking certain medications that increase the loss of magnesium in the urine. These medications include: 
  • Loop and thiazide diuretics (such as Bumex, Edecrin, Hydroclorothiazide, Lasix)
  • Some types of chemotherapy (Cisplatin, for example)
  • Certain antibiotics (Gentamicin, Amphotericin, and Cyclosporin)
• Alcoholics who tend to consume magnesium-poor diets and have more magnesium losses in their urine
• Frail elderly individuals eating diets low in magnesium
• Individuals with poorly controlled diabetes who may have a higher need for magnesium and have greater losses of magnesium in the urine

If you have any of the conditions/diseases listed or take any of the medications associated with high risk for magnesium deficiency, it is important to discuss your concerns with your doctor or medical professional.

How is magnesium deficiency diagnosed?

The clinical symptoms of magnesium deficiency include muscle twitching, muscle cramps, numbness, irregular heartbeat, high blood pressure, loss of appetite, depression, confusion and seizures. A doctor or medical professional can diagnose magnesium deficiency by a blood test. Magnesium deficiency needs to be treated by a doctor or medical professional.

How is magnesium deficiency treated?

A doctor will decide the best way to treat magnesium deficiency depending upon the reason causing it. Mild magnesium deficiency is sometimes treated with a diet that includes more magnesium-rich foods. When magnesium deficiency is more severe, a doctor or medical professional may prescribe magnesium by pill or tablet. Intravenous magnesium may be necessary if malabsorption is the cause of deficiency.

Are magnesium supplements recommended for healthy bones?

Magnesium supplements are not recommended for the general healthy population. They are also not recommended for individuals at risk for or with osteoporosis. In fact, magnesium supplements have no proven benefit in reducing the risk for osteoporosis or fracture.

For most individuals, eating at least five servings of fruits and vegetables (especially those dark green leafy varieties) each day and choosing less processed foods will reduce your risk for magnesium deficiency. If you have any of the conditions/diseases or take any of the medications associated with high risk for magnesium deficiency, it is important to discuss your concerns with your medical professional.

Is it possible to consume too much magnesium?

The intake of too much magnesium does not occur from dietary sources. However, magnesium toxicity can occur from the excessive use of supplements or laxatives that contain magnesium. Toxicity is most common in individuals with decreased kidney function. The Institute of Medicine set a UL (Tolerable Upper Intake Level) for supplementary magnesium of 350 milligrams (mg) per day for teens and adults. Taking more than 350 mg/day of magnesium (from supplements) on a regular basis increases the risk of adverse reactions. Adverse reactions to excess magnesium include diarrhea and other more severe complications.