AUTHOR Dr. Carlos Orozco (BSc, MSc, ND, MD, PhD, FPAMS).
Magnesium is a cofactor in more than 300 enzyme systems that regulate diverse biochemical reactions in the body, including protein synthesis, muscle and nerve function, blood glucose control, and blood pressure regulation.
Magnesium, an abundant mineral in the body, is naturally present in many foods, added to other food products, available as a dietary supplement, and present in some medicines (such as antacids and laxatives). Magnesium is a cofactor in more than 300 enzyme systems that regulate diverse biochemical reactions in the body, including protein synthesis, muscle and nerve function, blood glucose control, and blood pressure regulation. Magnesium is required for energy production, oxidative phosphorylation, and glycolysis. It contributes to the structural development of bone and is required for the synthesis of DNA, RNA, and the antioxidant glutathione. Magnesium also plays a role in the active transport of calcium and potassium ions across cell membranes, a process that is important to nerve impulse conduction, muscle contraction, and normal heart rhythm.
Dietary surveys of people in the United States consistently show that intakes of magnesium are lower than recommended amounts. An analysis of data from the National Health and Nutrition Examination Survey (NHANES) of 2005–2006 found that a majority of Americans of all ages ingest less magnesium from food than their respective EARs; adult men aged 71 years and older and adolescent females are most likely to have low intakes. In a study using data from NHANES 2003–2006 to assess mineral intakes among adults, average intakes of magnesium from food alone were higher among users of dietary supplements (350 mg for men and 267 mg for women, equal to or slightly exceeding their respective EARs) than among nonusers (268 mg for men and 234 for women). When supplements were included, average total intakes of magnesium were 449 mg for men and 387 mg for women, well above EAR levels.
No current data on magnesium status in the United States are available. Determining dietary intake of magnesium is the usual proxy for assessing magnesium status. NHANES has not determined serum magnesium levels in its participants since 1974, and magnesium is not evaluated in routine electrolyte testing in hospitals and clinics.
Symptomatic magnesium deficiency due to low dietary intake in otherwise-healthy people is uncommon because the kidneys limit urinary excretion of this mineral. However, habitually low intakes or excessive losses of magnesium due to certain health conditions, chronic alcoholism, and/or the use of certain medications can lead to magnesium deficiency.
Early signs of magnesium deficiency include loss of appetite, nausea, vomiting, fatigue, and weakness. As magnesium deficiency worsens, numbness, tingling, muscle contractions and cramps, seizures, personality changes, abnormal heart rhythms, and coronary spasms can occur.
Severe magnesium deficiency can result in hypocalcemia or hypokalemia (low serum calcium or potassium levels, respectively) because mineral homeostasis is disrupted.
Groups at Risk of Magnesium Inadequacy
Magnesium inadequacy can occur when intakes fall below the RDA but are above the amount required to prevent overt deficiency. The following groups are more likely than others to be at risk of magnesium inadequacy because they typically consume insufficient amounts or they have medical conditions (or take medications) that reduce magnesium absorption from the gut or increase losses from the body.
People with gastrointestinal diseases
The chronic diarrhea and fat malabsorption resulting from Crohn’s disease, gluten-sensitive enteropathy (celiac disease), and regional enteritis can lead to magnesium depletion over time. Resection or bypass of the small intestine, especially the ileum, typically leads to malabsorption and magnesium loss.