March 21, 2017


Other name(s):

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

General description

Magnesium is an essential element. It plays a role in how more than 300 enzymes work. It’s needed for nerve and muscle activity. It also controls the electrical and muscular activity of the heart. Magnesium is found in many over-the-counter antacids and laxatives. Because it’s found in many food sources, magnesium deficiency is rare.

Magnesium has many jobs in the body. These include activating enzymes involved in reactions in the ATP/phosphate energy cycle and carbohydrate metabolism. It also participates in nerve conduction, helping control nerve irritability.

Magnesium plays a role in how bone and tooth enamel form and are structured. It’s needed to convert protein, carbohydrates, and lipids into energy. It also 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 is used as a laxative and bowel evacuant. This is especially true in the form of magnesium sulfate or magnesium citrate. Magnesium citrate is given to cleanse the bowel before taking X-rays, CT scans, or MRIs of the abdomen.

Magnesium is also used to prevent and treat low magnesium levels (hypomagnesemia). In hospitals, magnesium is used to treat preeclampsia and eclampsia. These issues happen during pregnancy and right after childbirth.

Magnesium works with calcium, vitamin D, and parathyroid hormone to make healthy bone tissue and tooth enamel. Your healthcare provider may prescribe magnesium supplements to treat certain heart problems. These include heart attack, heart rhythm issues, 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 studies.

Magnesium is said to help maintain health of muscles, bone, and nerve tissues. It may help with anxiety and depression. It may also induce sleep in people with insomnia. It’s also said to relieve premenstrual syndrome (PMS). It may prevent muscle cramps, muscle weakness, and fatigue. Magnesium has also been claimed to prevent heart disease, hardening of the arteries (arteriosclerosis), and high triglyceride levels.

Recommended intake

Magnesium is measured in milligrams (mg). The Recommended Dietary Allowance is RDA.



Infants (0–6 months)

30 mg*

Infants (6 months to 1 year)

75 mg*

Children (1–3 years)

80 mg

Children (4–8 years)

130 mg

Children (9–13 years)

240 mg

Boys (14–18 years)

410 mg

Girls (14–18 years)

360 mg

Men (19–30 years)

400 mg

Women (19–30 years)

310 mg

Men (31 years and older)

420 mg

Women (31 years and older)

320 mg

Pregnant women (14–18 years)

400 mg

Pregnant women (19–30 years)

350 mg

Pregnant women (31 years and older)

360 mg

Breastfeeding women

No change

*Adequate Intake (AI)

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

Dosage is expressed as the amount of magnesium in the supplement. Or it’s expressed as the percentage of magnesium in it. Be sure to read the label closely to see how it’s expressed. You can learn the equivalent amount of elemental magnesium by multiplying the percentage of magnesium in the form by ten. One gram of magnesium oxide contains 60.3% of magnesium or 603 mg.

You should take magnesium supplements with food. This can help prevent diarrhea.

Some people need more magnesium than others. These include people with diabetes, malabsorption syndromes, and kidney disease. These also include people who take water pills (diuretics) regularly. Having vomiting or diarrhea, especially over a long period of time, can deplete your magnesium stores. Burns over large areas of the body, extreme athletic performance, or moderate-to-heavy alcohol use of may also increase how much magnesium you need. Athletes who restrict calories may need 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 in nearly all foods, it’s rare to have a diet lacking in magnesium. Signs of deficiency may include weakness, confusion, muscle tremor, abnormal heart rhythm, and lack of coordination. They also include personality changes, gastrointestinal disorders, and loss of appetite.

Side effects, toxicity, and interactions

Taking too much magnesium can cause diarrhea. This is the most common side effect. It can also cause low blood pressure (hypotension), muscle weakness, nausea, and vomiting.

Magnesium supplements may be dangerous for people with kidney issues. Supplements may also be dangerous if you have a heart block.

Women who are pregnant or breastfeeding talk to their healthcare providers before taking any supplements.

Magnesium is used in many antacid forms. These can cause diarrhea. Taking magnesium with food may help prevent this side effect.

Magnesium may interact with some medicines. These include bisphosphonates, some antibiotics, diuretics, and proton pump inhibitors. Tell your healthcare provider about all medicines you take before you start using magnesium supplements.


March 21, 2017

Reviewed By:  

Poulson, Brittany, RD, CDE,Wilkins, Joanna, R.D., C.D.