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Facts About Magnesium

Linda B. Bobroff
Contacts: Wendy Dahl

Why do we need magnesium?

Magnesium is a mineral needed by every cell in the body. More than 300 chemical reactions in the body require magnesium. Magnesium helps to:

  • support normal muscle and nerve function;
  • keep a steady heartbeat;
  • keep bones strong;
  • make protein and DNA; and
  • use energy from the foods we eat.
Every cell in your body needs magnesium, so it is important to get enough in your diet.
Figure 1. Every cell in your body needs magnesium, so it is important to get enough in your diet.

Credit: iStockphoto

What happens if we don't get enough magnesium?

Many Americans don’t get enough magnesium in their diets. However, most healthy people do not exhibit signs of deficiency, even if their intake is low, because the body stores this mineral. People who abuse alcohol, take certain diuretic drugs, or have kidney disease may be at risk for magnesium deficiency. Long-lasting diarrhea or vomiting can also cause a deficiency. Older adults often do not get enough magnesium in their diets.

The following conditions can be signs of magnesium deficiency or other medical problems. Check with your doctor if you have:

  • loss of appetite;
  • confusion;
  • abnormal heartbeat;
  • muscle cramps;
  • high blood pressure; or
  • seizures.

Table 1. Recommended daily intakes of magnesium.

Life Stage

Amount

(mg/day)

Men, ages 19–30

400

Men, ages 31+

420

Women, ages 19–30

310

Women, ages 31+

320

Pregnancy, ages 19–30

350

Pregnancy, ages 31+

360

Breastfeeding, ages 19–30

310

Breastfeeding, ages 31+

320

mg = milligrams of magnesium

How can we get enough magnesium?

The best sources of magnesium are nuts, legumes, seeds, dark green vegetables, seafood, and whole grains. We can get enough magnesium by eating a variety of these foods every day. Some sources of “hard” water contain magnesium.

Table 2. Food sources of magnesium.

Food

Magnesium*

(mg/serving)

Sesame seeds, toasted, 1 ounce

100

Almonds, roasted, 1 ounce

80

Avocado, Florida, 1 medium

75

Spinach, cooked, 1/2 cup

75

Wheat germ, 1/4 cup

70

Oatmeal, cooked, 1 cup

65

100% bran flakes cereal, 3/4 cup

65

Black beans, cooked, 1/2 cup

60

Potato, baked, with skin, 1 medium

50

Peanuts, dry roasted, 1 ounce

50

Whole-wheat bread, 2 slices

45

Figs, dried, 5

30

Banana, medium

30

Halibut, cooked, 3 ounces

25

mg = milligrams of magnesium

*USDA, Agricultural Research Service, National Research Library, https://fdc.nal.usda.gov

 

Nuts such as almonds and cashews are good sources of magnesium.
Figure 2. Nuts such as almonds and cashews are good sources of magnesium.

Credit: iStockphoto

What about supplements?

People who eat a variety of healthy foods generally don’t need magnesium supplements. However, people with certain diseases or those taking specific medications may require additional magnesium. Your health care provider can tell you if you need to take a magnesium supplement.

How much is too much?

Magnesium is found in some over-the-counter drugs, including “milk of magnesia” and some antacids. Large doses of these products or magnesium supplements can cause nausea, diarrhea, and stomach cramps. Magnesium from foods does not cause these symptoms. You should not exceed 350 mg of magnesium per day from supplements or medications.

Where can I find more information?

The UF/IFAS Extension Family and Consumer Sciences (FCS) agent at your local UF/IFAS Extension office may have more information or nutrition classes for you to attend (find your local UF/IFAS Extension office at https://sfyl.ifas.ufl.edu/find-your-local-office/). Also, a registered dietitian (RD) can provide reliable information.

The following websites also have reliable information: