What does a magnesium supplement do?

January 2021

Why Magnesium is Important

Magnesium is a mineral that everyone needs for their bodies to work correctly, but that many people do not get enough of. The body relies on various enzymes, which are proteins that facilitate various biological processes. More than 300 of these processes rely on magnesium for producing energy, controlling blood sugar, producing hormones, and many other critical functions. [1, 2, 3] For example, magnesium plays a key role in:

  1. Preserving adenosine triphosphate (ATP), which plays a crucial role in producing energy in humans. Without enough magnesium, ATP degrades quickly when there are high pH levels in the blood, which can lead to muscle weakness, fatigue, and a general inability to function physically at optimal levels.
  2. Synthesizing new proteins by helping ribozymes attach to mRNA; these proteins in turn control cell growth.
  3. Producing DNA and RNA molecules.
  4. Regulating the levels of various nutrients in the body, including calcium, vitamin D, zinc, copper, sodium, and potassium.
  5. Helping prevent a variety of health conditions, including depression, diabetes, osteoporosis, kidney stones, and insulin resistance.

Magnesium does not work effectively by itself, but rather has to be bonded with another compound before the body can use it. Supplements typically bind magnesium with citrate, oxide, or chloride to help the intestines process it.

Why Take a Magnesium Supplement?

Given that magnesium is crucial for good overall health, it is important to make sure you consume enough of it. Unfortunately, although most people are not severely deficient in magnesium, it is difficult to get the recommended daily allowance (RDA). That is largely because modern industrial farming practices have depleted the soil of much of its magnesium, and modern food processing methods eliminate much of the rest. This means that most Americans only get about half of the RDA. Several health conditions can exacerbate a magnesium deficiency, including heart disease, diabetes, pancreatitis, hypertension, kidney disease, hyperthyroidism, osteoporosis, migraines, and gastrointestinal illness. A preexisting magnesium deficiency can also help cause those conditions [3, 4]. Older people are at particular risk for magnesium deficiency because they do not absorb nutrients as well and their kidneys excrete it at a higher rate compared to other adults [1].

It is difficult to detect a magnesium deficiency with a standard blood test because most magnesium is stored in bones and soft tissues. In fact, a blood test can only detect 0.3% of the total amount of magnesium in the body. This means that a blood test will not detect a deficiency unless it is severe, in which case you will probably have other symptoms like irritability and fatigue. However, even a moderate magnesium deficiency can inhibit the crucial biological processes described above.

Recommended Dosage

How much magnesium you need depends on a variety of factors, including age, gender, and weight.

The U.S. government generally recommends that adults get a total of 6 milligrams of magnesium/kg per day from food and supplements. This means, for example, that a 75 kg (165 lb) male should consume 450 mg of magnesium per day, a 100 kg (220 lb) male should intake 600 mg of magnesium per day, and a 60 kg (132 lb) female should intake 360 mg of magnesium per day. [3, 5] However, other healthcare professionals recommend higher amounts—up to 600 to 800 mg per day from all sources for adults. It is important to note that children should not take magnesium supplements unless ordered by a doctor.

When taking a magnesium supplement, pay attention to dosage because the body absorbs magnesium most efficiently in relatively small doses of 100 to 125 mg. If you take more than that in one sitting, much of it will simply be excreted. Aim for 300 mg of magnesium in supplement form per day, as this amount, combined with a healthy diet, should ensure adequate levels. Also note that zinc and magnesium supplements should not be taken at the same time because zinc keeps the body from absorbing as much magnesium as it otherwise would. Also make sure you are getting enough vitamin B6, which is essential for processing magnesium correctly. Finally, talk to your doctor before taking a magnesium supplement, especially if you have certain health issues such as severe kidney disease, diabetes, hypertension, or heart disease. [6]

Which is the Best Magnesium Supplement?

Check out our unbiased recommendation of the best products on the market using our rigorous methodology. We screen products for the right formulation, bioavailability, safety, and efficacy to bring you only the best supplements available in 2019.

1. Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride.” Washington, DC: The National Academies Press, 1997, 190-240. Available at:
2. Jahnen-Dechent, W., Ketteler, M. “Magnesium Basics.” Clinical Kidney Journal 5, 3-14 (2012).
3. Riley, P. Thomas. “Magnesium.” University of Mary Washington Student Health Center. July 2011.
4. “Magnesium: Fact Sheet for Health Professionals.” National Institutes of Health, Office of Dietary Supplements. February 2016.
5. Seelig, Mildred S. “The Requirement of Magnesium by the Normal Adult.” The American Journal of Clinical Medicine. Vol. 14. 6 (June 1964).
6. Magnesium Supplement (Oral Route, Parenteral Route).” Mayo Clinic. January 2016.