Other name(s):

magnesium carbonate, magnesium citrate, magnesium hydroxide, magnesium oxide, magnesium sulfate

General description

Magnesium is an essential element involved in the proper functioning of more than 300 enzymes. It is required for nerve and muscle activity, and to regulate the electrical and muscular activity of the heart. Magnesium is found in many over-the-counter antacids and laxatives. Because magnesium is found in many food sources, magnesium deficiency is rare.

Magnesium has many functions in the body. Important actions include activating enzymes involved in reactions in the ATP/phosphate energy cycle and carbohydrate metabolism, participating in nerve conduction, helping regulate nerve irritability.

Magnesium plays an essential role in the formation and structure of bone and tooth enamel. It is required to convert protein, carbohydrates and lipids into energy, and it aids in the synthesis of protein, RNA, and DNA. Magnesium is involved in the breakdown (metabolism) of many substances in the body.

Medically valid uses

Magnesium, particularly in the form of magnesium sulfate or magnesium citrate, is used as a laxative and bowel evacuant. Magnesium citrate is typically given to cleanse the bowel before taking X-rays, CT scans, or MRIs of the abdomen.

Magnesium is also used to prevent and treat hypomagnesemia (low magnesium levels). In hospitals, magnesium is used to treat pre-eclampsia and eclampsia, conditions occurring during pregnancy and immediately after delivery.

In conjunction with calcium, vitamin D and parathyroid hormone, magnesium is essential for the production of healthy bone tissue and tooth enamel. Magnesium supplements may be prescribed to treat certain heart conditions, such as heart attack, heart rhythm abnormalities, cardiac surgery, congestive heart failure, and digitalis poisoning. It may also be used during cardiac surgery.

Unsubstantiated claims

Please note that this section reports on claims that have NOT yet been substantiated through scientific studies.

Magnesium is said to be useful in maintaining the health of muscles, bone, and nerve tissues. It may help with anxiety and depression, induce sleep in people suffering from insomnia, and relieve PMS. It is said to prevent muscle cramps, muscle weakness, and fatigue. Magnesium has also been purported to prevent heart disease, arteriosclerosis (hardening of the arteries), and high triglyceride levels.

Recommended intake

As indicated below, magnesium is measured in milligrams (mg). The DRI is the Dietary Reference Intake.



Infants (0 to 6 months)

30 mg

Infants (6 months to 1 year)

75 mg

Children (1 to 3 years)

80 mg

Children (4 to 8 years)

130 mg

Boys (9 to 13 years)

240 mg

Girls (9 to 13 years)

240 mg

Boys (14 to 18 years)

410 mg

Girls (14 to 18 years)

360 mg

Men (19 to 30 years)

400 mg

Women (19 to 30 years)

310 mg

Men (31+ years)

420 mg

Women (31+ years)

320 mg

Pregnant women

+ 40 mg

Breastfeeding women

No change

Magnesium supplements come in many forms. Each form has a different percentage of magnesium. Magnesium oxide and magnesium hydroxide contain the highest concentrations of magnesium, with magnesium gluconate and magnesium gluceptate containing the lowest.

Dosage is expressed either as the amount of magnesium present or the percentage of magnesium in the preparation. Be sure to read the label carefully to see if it expresses the amount of elemental magnesium or the total weight of the compound. The equivalent amount of elemental magnesium can be calculated by multiplying the percentage of magnesium in the preparation by ten. Thus, 1 gram of magnesium oxide contains 60.3 percent of magnesium, or 603 mg.

Photo of almonds in a dish

To prevent diarrhea, magnesium supplements should be taken with food.

Increased need for magnesium occurs in people with diabetes, malabsorption syndromes, or kidney disease, as well as in people who regularly take diuretics (water pills). Vomiting or diarrhea, especially over a long period of time, can deplete the body's magnesium stores. Burns over large areas of the body, extreme athletic performance, or moderate-to-heavy use of alcohol may also increase magnesium requirements. Athletes who restrict calories may require magnesium supplements.

Food source

Nutrient content per 100 grams


267 mg


252 mg

Brewer's yeast

231 mg


181 mg

Peanut butter

178 mg


158 mg


134 mg

Kidney beans

132 mg

Dried figs

82 mg

Beet tops

71 mg


70 mg

Lima beans

66 mg

Because magnesium is present in nearly all foods, diets deficient in magnesium are rare. Signs of deficiency may include weakness, confusion, muscle tremor, abnormal heart rhythm, lack of coordination, personality changes, gastrointestinal disorders, and loss of appetite.

Side effects, toxicity, and interactions

Taking too much magnesium can result in diarrhea (the most common side effect), low blood pressure (hypotension), and muscle weakness. Severe nausea and vomiting can also result.

Magnesium supplements may be dangerous for people with chronic renal failure or impaired kidney function. Supplements may also be dangerous if you have a heart block.

Women who are pregnant or breastfeeding should consult a physician before taking any mineral supplements.

Magnesium is used in many antacid formulations and can cause diarrhea. Taking magnesium preparations with food may reduce the symptoms.

Additional information

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