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Magnesium: Health Benefits and Deficiency Symptoms

Magnesium is an essential mineral with many important roles in the body. These include helping to create bone and other tissues, converting food to energy and supporting the activity of more than 300 enzymes that spark vital chemical reactions in the body.

An average person has about 25-30 grams of magnesium in the body with 50-75% of this amount present in the bones. Magnesium combines with calcium and phosphorus in bone formation. Most of the remaining magnesium resides in the muscles and soft tissue and just a tiny fraction is found in the blood.

A blood test is available to check magnesium serum levels. Low levels of magnesium in the blood are known as hypomagnesemia. Hypomagnesemia can be caused by starvation and intestinal malabsorption of magnesium.

Abnormally high levels of magnesium in the blood are known as hypermagnesemia. This condition may occur in patients with kidney failure who take magnesium salts or in those who use magnesium-containing medications such as laxatives or antacids.

Recommended dietary allowances (RDAs) for magnesium in milligrams (mg)

Age Male Female
Birth to 6 months 30 30
7-12 months 75 75
1-3 years 80 80
4-8 years 130 130
9-13 years 240 240
14-18 years 410 360 (incl. lactating), pregnant 400
19-30 years 400 310 (incl.lactating), pregnant 350
31 years and older 420 320 (incl. lactating), pregnant 360

Tolerable upper intake levels for magnesium in milligrams (mg)

Age Male Female
Birth to 12 months None established None established
1-3 years 65 65
4-8 years 110 110
9-18 years 350 350 (incl. pregnant and lactating)
19 years and older 350 350 (incl. pregnant and lactating)

Health Effects of Magnesium

Magnesium helps the body to make body tissue, particularly bone. It also plays a vital role in the work of more than 300 human enzymes. Enzymes regulate various bodily functions. These include generating energy for the body, creating protein and signalling muscles when to contract and relax.

Magnesium is a component in bone and holds calcium in tooth enamel. It also helps maintain nerve and muscle cells and promotes normal functioning of the immune system. This mineral is important for the use and regulation of adenosine triphosphate, which transports chemical energy within cells for metabolism. Magnesium appears to help protect against heart disease by reducing the amount of oxygen needed to convert food to energy. Other health effects of magnesium include:

  • Helps the body maintain a proper blood sugar level
  • Is involved in energy metabolism and protein synthesis
  • Moves nutrients into and out of the cells
  • Promotes normal blood pressure
  • Sends messages between the cells
  • Transmits the genetic code when cells divide and reproduce

A growing body of evidence suggests that adequate intake of magnesium can help reduce the risk of developing high blood pressure, cardiovascular disease, migraine headaches and diabetes (insulin resistance). Magnesium also has an essential role in the body’s detoxification process because it is necessary for the production of glutathione, the body’s master antioxidant. In addition, young girls who eat a diet rich in magnesium may increase the strength of their bones.

Magnesium Deficiency

In fact, most Western diets do not seem to provide the recommended levels of magnesium. But, magnesium found in hard drinking water and mineral water helps to make up this deficit. As a result, magnesium deficiency is relatively rare. Deficiency of magnesium usually occurs if the body cannot properly absorb magnesium due to a serious gastrointestinal disorder like inflammatory bowel disease. Other conditions that are associated with low levels of magnesium include:

  • Administration of excessive insulin
  • Alcohol abuse
  • Chronic diarrhea
  • Delirium tremens (alcohol withdrawal syndrome)
  • Hyperaldosteronism (syndrome marked by increased levels of hormone aldosterone)
  • Hypoparathyroidism (low levels of parathyroid hormone)
  • Kidney disorders
  • Liver cirrhosis
  • Pancreatitis (inflammation of the pancreas)
  • Prolonged vomiting
  • Protein malnutrition
  • Toxemia of pregnancy (elevated blood pressure and protein in urine)
  • Ulcerative colitis (chronic inflammatory disease of the large intestine)
  • Use of certain medications (e.g., diuretics, antibiotics, antifungals, proton-pump inhibitors and chemotherapy drugs)

Symptoms of magnesium deficiency typically begin with loss of appetite, nausea, vomiting fatigue and weakness. Then they progress to include tingling, numbness, muscle contractions, cramps, seizures, coronary spasms, abnormal heartbeat, personality changes and central nervous system problems (e.g., memory loss, confusion, hallucinations). Chronic magnesium deficiency is also associated with hypokalemia, low levels of potassium in the blood, and hypocalcemia, low levels of calcium in the blood, which in turn may raise the risk of developing osteoporosis.

Magnesium Overdose

Magnesium toxicity is rare in healthy people because excessive amounts are naturally excreted in the urine and feces. However, magnesium overdose can be potentially fatal in people with kidney problems. Toxicity is rarely related to a diet high in magnesium and is almost always a result of intake of supplements, especially when combined with impaired kidney function. For instance, elderly who take large doses of antacids and laxatives that contain magnesium are at risk of magnesium toxicity. High levels of magnesium can also be caused by the following conditions:

  • Addison’s disease (hormone deficiency)
  • Chronic kidney failure
  • Diabetic acidosis (build-up of byproducts of fat metabolism)
  • Oliguria (decreased urine output)
  • Severe dehydration

Symptoms of magnesium overdose. Overdose may cause a condition known as metabolic alkalosis (high alkalinity of the blood and body fluids). Symptoms of magnesium toxicity include diarrhea, dehydration, appetite loss, nausea, muscle weakness, changes in mental status, low blood pressure, breathing problems, irregular heartbeat and cardiac arrest.

Dietary Sources of Magnesium

Magnesium can be found in many different types of food. In particular, dark green vegetables are rich in magnesium because it is present in the chlorophyll molecules that give these vegetables their characteristic green color. The best dietary sources of magnesium include:

  • All bran
  • Bitter chocolate
  • Cocoa
  • Dark green vegetables (e.g., spinach, chard, collards, seaweed)
  • Fruits (e.g., dried figs and apricots, dates, avocados, bananas)
  • “Hard” tap water and mineral water
  • Legumes (e.g., beans, peas)
  • Nuts (e.g., cashews, almonds, Brazil nuts, peanuts, pecans, hazelnuts, walnuts)
  • Potato
  • Seafood (e.g., conch, winkles, shrimp, whelks, crab)
  • Soy products
  • Whole grains (and not refined grains such as white flour)
  • Whole seeds

Magnesium Supplementation

Magnesium can also be obtained in supplement form. Several different types of supplements are available in both over-the-counter and prescription formulations. They contain different magnesium compounds (e.g., oxide, carbonate, hydroxide, citrate, lactate, chloride and sulfate). Most people use magnesium supplements to prevent migraines and cluster headaches. Elderly people, who often have impaired magnesium absorption and increased renal excretion, may also be urged to take magnesium supplements.

Other conditions that can be treated with magnesium supplements include alcoholism, chronic malabsorptive problems and diabetes (hyperglycemia). Abnormally low magnesium levels (hypomagnesemia) may require prescription magnesium tablets or intravenous magnesium replacement.