11.4 – Magnesium

Learning Objectives

  • Discuss the roles of magnesium in the body
  • List food groups that are dietary sources of magnesium.


Magnesium’s Functional Role

Approximately 60 percent of magnesium in the human body is stored in the skeleton, making up about 1 percent of mineralized bone tissue. Magnesium is not an integral part of the hard mineral crystals, but it does reside on the surface of the crystal and helps maximize the bone structure. Observational studies link magnesium deficiency with an increased risk for osteoporosis. A magnesium-deficient diet is associated with decreased levels of parathyroid hormone and the activation of vitamin D, which may lead to an impairment of bone remodeling. A study in nine hundred elderly women and men did show that higher dietary intakes of magnesium correlated to an increased bone mineral density (B.M.D.) in the hip.1 Only a few clinical trials have evaluated the effects of magnesium supplements on bone health and their results suggest some modest benefits on B.M.D..

In addition to participating in bone maintenance, magnesium has several other functions in the body. In every reaction involving the cellular energy molecule, A.T.P., magnesium is required. More than three hundred enzymatic reactions require magnesium. Magnesium plays a role in the synthesis of DNA and RNA, carbohydrates, and lipids, and is essential for nerve conduction and muscle contraction. Another health benefit of magnesium is that it may decrease blood pressure.

Many Americans do not get the recommended intake of magnesium from their diets. Some observational studies suggest mild magnesium deficiency is linked to increased risk for cardiovascular disease. Signs and symptoms of severe magnesium deficiency may include tremor, muscle spasms, loss of appetite, and nausea.

1 Tucker KL, Hannan MT, et al. Potassium, Magnesium, and Fruit and Vegetable Intakes Are Associated with Greater Bone Mineral Density in Elderly Men and Women. Am J Clin Nutr. 1999; 69(4), 727–36. Accessed June 30, 2019.


Dietary Reference Intake and Food Sources for Magnesium

The R.D.A.s for magnesium for adults between ages nineteen and thirty are 400 milligrams per day for males and 310 milligrams per day for females. For adults above age thirty, the R.D.A. increases slightly to 420 milligrams per day for males and 320 milligrams for females.


Table 10.5.1: Dietary Reference Intakes for Magnesium.
A table that shows magnesium dietary reference intake amounts for several different age ranges
Age Group R.D.A.(milligrams per day) U.L. From non-food sources (milligrams per day)
Infants (0–6 months) 30* None
Infants (6–12 months) 75* None
Children (1–3 years) 80 65
Children (4–8 years) 130 110
Children (9–13 years) 240 350
Adolescents (14–18 years) 410 350
Adults (19–30 years) 400 350
Adults (> 30 years) 420 350

* denotes Adequate Intake
Source: Dietary Supplement Fact Sheet: Magnesium. National Institutes of Health, Office of Dietary Supplements. Updated September 26, 2018. Accessed June 30, 2019.

Dietary Sources of Magnesium

Magnesium is part of the green pigment, chlorophyll, which is vital for photosynthesis in plants; therefore green leafy vegetables are a good dietary source for magnesium. Magnesium is also found in high concentrations in fish, dairy products, meats, whole grains, and nuts. Additionally chocolate, coffee, and hard water contain a good amount of magnesium. Most people in America do not fulfill the R.D.A. for magnesium in their diets. Typically, Western diets lean toward a low fish intake and the unbalanced consumption of refined grains versus whole grains.


Table 10.5.2: Magnesium Content of Various Foods
A table that shows different food sources for magnesium
Food Serving Magnesium (milligrams) Percent Daily Value
Almonds 1 oz. 80 20
Cashews 1 oz. 74 19
Soymilk 1 c. 61 15
Black beans ½ c. 60 15
Edamame ½ c. 50 13
Bread 2 slices 46 12
Avocado 1 c. 44 11
Brown rice ½ c. 42 11
Yogurt 8 oz. 42 11
Oatmeal, instant 1 packet 36 9
Salmon 3 oz. 26 7
Chicken breasts 3 oz. 22 6
Apple 1 medium 9 2

Source: Dietary Supplement Fact Sheet: Magnesium. National Institutes of Health, Office of Dietary Supplements. Updated September 26, 2018. Accessed June 30, 2019.


University of Hawai’i at Mānoa Food Science and Human Nutrition Program: Allison Calabrese, Cheryl Gibby, Billy Meinke, Marie Kainoa Fialkowski Revilla, and Alan Titchenal


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Nutrition 100 Nutritional Applications for a Healthy Lifestyle Copyright © by Lynn Klees and Alison Borkowska is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.

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