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Magnesium

Other name(s):

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

General description

Magnesium is an essential mineral. It helps more than 300 enzymes work. It’s needed for nerve and muscle activity. It also controls the electrical and muscle activity of the heart. Magnesium is in many antacids and laxatives. It's found in many foods. Because of this, magnesium deficiency is rare.

Magnesium is needed for many functions in the body. These include:

  • Activating enzymes that help break down carbohydrates

  • Nerve conduction

  • Helping control nerve irritability

Magnesium helps bone and tooth enamel form. It’s needed to convert protein, carbohydrates, and lipids into energy. It also helps make protein, RNA, and DNA. Magnesium helps break down (metabolize) many substances in the body.

Medically valid uses

Magnesium can be used as a laxative. This is often done 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.

It's used in some treatments for heartburn and upset stomach due to acid indigestion.

Magnesium is also used to prevent and treat low magnesium levels. This is called hypomagnesemia. In hospitals, magnesium is used to treat preeclampsia and eclampsia. These issues can happen in 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 to treat certain heart problems. These include: 

  • Heart attack

  • Heart rhythm problems

  • Heart failure

  • Digitalis poisoning

It may also be used during cardiac surgery.

Unsubstantiated claims

There may be benefits that have not yet been proven through research.

Magnesium may:

  • Help maintain health of muscles, bone, and nerve tissues

  • Help with anxiety and depression

  • Induce sleep in people with insomnia

  • Relieve premenstrual syndrome (PMS)

  • Prevent muscle cramps, muscle weakness, and fatigue

  • Prevent heart disease

  • Prevent hardening of the arteries (arteriosclerosis)

  • Prevent high triglyceride levels

Recommended intake

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

Group

RDA

Infants (0–6 months)

30 mg*

Infants (7 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 amount of magnesium. Magnesium oxide and magnesium hydroxide have the highest amounts of it. Magnesium gluconate and magnesium gluceptate have the lowest.

Dose may be noted as the amount of magnesium. Or it may be noted as the percentage. Read the label to see how it is noted. You can learn the amount of elemental magnesium in a food. To do this, multiply the percentage of magnesium by 10. One (1) gram of magnesium oxide has 60.3% magnesium or 603 mg.

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

You may need more magnesium if you have any of these:

  • Diabetes

  • A malabsorption syndrome

  • Kidney disease

  • Take water pills (diuretics) regularly

  • Having vomiting or diarrhea

  • Have burns over large areas of the body

  • Extreme athletic activity

  • Moderate-to-heavy alcohol use

You may also need more magnesium if you are an athlete who restricts calories.

Food source

Nutrient content

Almonds, 1 oz.

80 mg

Spinach, boiled, 1 cup

78 mg

Cashews, 1 oz.

74 mg

Peanuts, ¼ cup

63 mg

Soy milk, plain or vanilla, 1 cup

61 mg

Black beans, cooked, ½ cup

60 mg

Yogurt, plain, low-fat, 8 oz.

42 mg

Kidney beans, ½ cup

35 mg

Banana, 1 medium

32 mg

Salmon, cooked, 3 oz.

26 mg

Milk, 1 cup

24 mg

Raisins, ½ cup

23 mg

Magnesium is in nearly all foods. Because of this, it’s rare to have a diet low in magnesium. Signs of deficiency may include:

  • Weakness

  • Confusion

  • Muscle tremor

  • Abnormal heart rhythm

  • Lack of coordination

  • Personality changes

  • Gastrointestinal disorders

  • 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

  • Vomiting

Magnesium supplements may be dangerous for some people. This includes:

  • People with kidney problems

  • People with a heart block

Women who are pregnant or breastfeeding should 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 change the effects of some medicines. These include:

  • Antibiotics

  • Diuretics

  • Proton pump inhibitors

Tell your healthcare provider about all medicines you take before you take magnesium.

Online Medical Reviewer: Bianca Garilli MD
Online Medical Reviewer: Chris Southard RN
Online Medical Reviewer: Jessica Gotwals RN BSN MPH
Date Last Reviewed: 8/1/2023