Facts about Magnesium¹

Jennifer Hillan and Linda B. Bobroff²

Why do we need magnesium?

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

support normal muscle and nerve function
keep a steady heartbeat
keep bones strong
make protein and DNA
use energy from the foods we eat

What happens if we don't get enough magnesium?

Many Americans don’t get enough magnesium in their diets. While most healthy people do not have signs of deficiency 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 also can 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:

appetite loss,
confusion,
abnormal heartbeat,
muscle cramps,
high blood pressure,
seizures.

How much magnesium do we need?

The following table lists recommended daily intakes of magnesium:

Table 1.

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 add magnesium to the diet.

Here are some foods and the amount of magnesium they contain:

Table 2.

Food	Magnesium (mg/serving)
100% bran cereal, ½ cup	130
Avocado, Florida, 1 medium	105
Sesame seeds, 1 ounce	100
Wheat germ, toasted, ¼ cup	95
Halibut, cooked, 3 ounces	90
Almonds, dry roasted, 1 ounce	85
Spinach, cooked, ½ cup	80
Black beans, cooked, ½ cup	60
Oatmeal, cooked, 1 cup	55
Figs, dried, 5	55
Potato, baked, with skin, 1 medium	55
Peanuts, dry roasted, 1 ounce	50
Whole wheat bread, 2 slices	50
Brown rice, cooked, ½ cup	45
mg = milligrams of magnesium

What about supplements?

People who eat an adequate amount of a variety of healthy foods generally don’t need magnesium supplements. However, people who have certain diseases or take certain medications may need extra magnesium. Your healthcare provider can tell you if you need to take a magnesium supplement.

How much is too much?

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

Where can I get more information?

The Family and Consumer Sciences (FCS) agent at your county Extension office may have more written information for you as well as nutrition classes for you to attend. Also, a registered dietitian (RD) can provide reliable information to you.

Reliable nutrition information may be found on the Internet at these sites:

http://fycs.ifas.ufl.edu

http://www.nutrition.gov

http://ods.od.nih.gov/

http://www.nlm.nih.gov/medlineplus/ency/article/002405.htm

Footnotes

This document is FCS8810, one of a series of the Department of Family, Youth and Community Sciences, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date April 8, 2009. Please visit the EDIS website at http://edis.ifas.ufl.edu.

Jennifer Hillan, MSH, RD, LD/N, former ENAFS Nutrition Educator and Linda B. Bobroff, professor, Department of Family, Youth and Community Sciences, Institute of Food and Agricultural Sciences, University of Florida, Gainesville FL 32611.

The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other extension publications, contact your county Cooperative Extension service.

U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, Dean.

Facts about Magnesium1