Magnesium

Magnesium is a mineral that's crucial to the body's function. Magnesium helps keep blood pressure normal, bones strong, and the heart rhythm steady.

Why do people take magnesium?

Experts say that many people in the U.S. aren't eating enough foods with magnesium. Adults who consume less than the recommended amount of magnesium are more likely to have elevated inflammation markers. Inflammation, in turn, has been associated with major health conditions such as heart disease, diabetes, and certain cancers. Also, low magnesium appears to be a risk factor for osteoporosis.

There's some evidence that eating foods high in magnesium and other minerals can help prevent high blood pressure in people with prehypertension.

Intravenous or injected magnesium is used to treat other conditions, such as eclampsia during pregnancy and severe asthma attacks. Magnesium is also the main ingredient in many antacids and laxatives.

Severe magnesium deficiencies are rare. They're more likely in people who:

Health care providers sometimes suggest that people with these conditions take magnesium supplements.

Proton pump inhibitors (PPIs) a common type of medicine used to treat acid reflux, have also been tied to low magnesium levels. Examples of PPIs include dexlansoprazole (Dexilant), esomeprazole (Nexium), lansoprazole (Prevacid), omeprazole (Prilosec, Zegerid), pantoprazole (Protonix), and rabeprazole (Aciphex). If you take any of these medicines on a long-term basis, your health care provider may check your magnesium level with a blood test.

 

How much magnesium do you need?

The recommended dietary allowance (RDA) includes the magnesium you get from both the food you eat and any supplements you take.

Category

Recommended Dietary Allowance (RDA)

CHILDREN

1-3 years

80 mg/day

4-8 years

130 mg/day

9-13 years

240 mg/day

FEMALES

14-18 years

360 mg/day

19-30 years

310 mg/day

31 years and over

320 mg/day

Pregnant

Under 19 years: 400 mg/day
19 to 30 years: 350 mg/day
31 years and up: 360 mg/day

Breastfeeding

Under 19 years: 360 mg/day
19 to 30 years: 310 mg/day
31 years and up: 320 mg/day

MALES

14-18 years

410 mg/day

19-30 years

400 mg/day

31 years and up

420 mg/day

Continued

Most people get more than enough magnesium from foods and do not need to take magnesium supplements. Excessive use of magnesium supplements can be toxic. In addition to what you get from food, the highest dose you should take of magnesium supplements is:

  • 65 mg/day for children ages 1-3
  • 110 mg/day for children ages 4-8
  • 350 mg/day for adults and children ages 9 and up

These doses are the highest somebody should add to his or her diet. Many people ingest significant quantities of magnesium through the foods they eat. It's safe to get high levels of magnesium naturally from food, but adding large amounts of supplements to your diet can prove dangerous. Do not exceed these maximum advised levels.

 

Can you get magnesium naturally from foods?

Natural food sources of magnesium include:

  • Green, leafy vegetables, like spinach
  • Nuts
  • Beans, peas, and soybeans
  • Whole-grain cereals

Eating whole foods is always best. Magnesium can be lost during refinement and processing.

What are the risks of taking magnesium?

  • Side effects. Magnesium supplements can cause nausea, cramps, and diarrhea. Magnesium supplements often cause softening of stool.
  • Interactions. Magnesium supplements may not be safe for people who take diuretics, heart medicines, or antibiotics. Check with your health care provider if you are taking any medicine before taking magnesium.
  • Risks. People with diabetes, intestinal disease, heart disease or kidney disease should not take magnesium before speaking with their health care provider.
  • Overdose. Signs of a magnesium overdose can include nausea, diarrhea, low blood pressure, muscle weakness, and fatigue. At very high doses, magnesium can be fatal.
WebMD Medical Reference Reviewed by Carmen Patrick Mohan on June 07, 2017

Sources

SOURCES:
Longe, J., ed. The Gale Encyclopedia of Alternative Medicine, second edition, 2004.
Office of Dietary Supplements: "Dietary Supplement Fact Sheet: Magnesium."

UpToDate: "Causes of hypomagnesemia."

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