A Magnesium Primer

by Kristen Horler on Jan 01, 2014

Imagine your muscles in a permanent state of contraction. Without magnesium to support the absorption of calcium, muscles cannot relax properly.

Magnesium is vital to the human body, helping with energy production and heart and bone health. Magnesium interacts with over 300 enzymes to help regulate protein synthesis, blood glucose, blood pressure and muscle and nerve function. Recent studies indicate magnesium affects glucose transport and insulin sensitivity (Duffine & Volpe 2013); this is especially important as we learn more about preventing and reversing type 2 diabetes and cardiovascular disease.

In the human body, 50% to 60% of magnesium is in our bones and 40% to 50% is in soft tissues. Less than 1% percent of magnesium is in our blood, which makes it difficult for a blood test to determine adequate magnesium levels. Fortunately, true magnesium deficiencies are rare, unless an illness resulting in vomiting or diarrhea causes a temporary shortfall. Other causes of magnesium deficiencies include taking diuretics and consuming too much coffee, soda, salt or alcohol. Symptoms of magnesium deficiency may include muscle weakness or spasms, restless-leg syndrome and abnormal heart rhythms.

If deficiencies are rare and tests have a hard time detecting deficiencies, should you take a magnesium supplement? That depends on what you eat. Because the standard American diet lacks magnesium-rich foods such as green leafy vegetables, it is likely we are not consuming enough magnesium. Ensuring your diet is rich in whole foods that naturally contain magnesium can help to improve many bodily functions.

Magnesium occurs naturally in many foods, including:

  • Quinoa
  • Spinach
  • Almonds
  • Cashews
  • White beans

Adults need 310 to 400 mg of magnesium daily, but popping a pill may not be the answer. Isolated vitamins and minerals do not have the same nutritional value as nutrients naturally occurring in whole foods (Lichtenstein & Russell 2005). If you decide to supplement, be aware that too much magnesium can result in loose stools.

Alternatively, eat one cup of cooked spinach to get 157 mg of magnesium; add black beans (120 mg), brown rice (80 mg), and a banana (41 mg) and you will meet your recommended dietary allowance of magnesium through whole food sources (Harvard Women’s Health Watch 2011).

Although you may not need much magnesium, consuming a well-rounded diet that is rich in fruits and vegetables should ensure you meet your magnesium requirements. Adequate magnesium levels support hundreds of processes in our body so that we can run, jump, play and lead an active, healthy life.



Duffine, A.E., & Volpe, S.L. 2013. Magnesium and Metabolic Disorders. In Magnesium in R.R. Watson, V.R. Preedy & S. Zibadi (Eds.), Human Health and Disease (pp. 129-138). New York, NY: Humana Press. http://link.springer.com/chapter/10.1007/978-1-62703-044-1_8#page-1; retrieved January 2, 2014.

Harvard Women’s Health Watch. 2011. Magnesium content in milligrams (mg) of certain foods. www.health.harvard.edu/newsletters/Harvard_Womens_Health_Watch/2011/December/magnesium-content-in-milligrams-mg-of-certain-foods.

Lichtenstein, A.H., & Russell, R.M. 2005. Essential Nutrients: Food or Supplements? Where Should the Emphasis Be? Journal of the American Medical Association, 294 (3), 351-358.

IDEA Food and Nutrition Tips, Volume 3, Issue 1

© 2014 by IDEA Health & Fitness Inc. All rights reserved. Reproduction without permission is strictly prohibited.

About the Author

Kristen Horler

Kristen Horler IDEA Author/Presenter

Kristen is an ACE certified personal trainer, AFAA certified group exercise instructor and continuing education provider for the American Council on Exercise and the Aerobics and Fitness Association o...

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