Should I Take a Magnesium Supplement?

By Jacqueline Larson M.S., R.D.N.

Should I Take a Magnesium Supplement?

Magnesium is a major mineral found in a variety of foods and beverages.  Green leafy vegetables, legumes, nuts, seeds, and whole grains are good sources. 

Over half of the magnesium found in the body is found in the bones.  The rest is found in the muscles, heart, liver and other soft tissues.  Our bodies help to protect against the supply of magnesium from getting too low by tapping to the supply of magnesium in the bones when needed.  The kidneys can also conserve the amount of magnesium excreted in the urine. 

Determining your magnesium status is difficult because most of the magnesium is found inside the cells or in bones. Your medical doctor can check your magnesium levels in your blood.  This may not always be a good measurement, because the body’s ability to maintain magnesium levels is controlled by pulling needed magnesium from the bones and cells or preventing the kidneys from excreting out too much magnesium. Other methods of testing magnesium status include measuring magnesium concentrations in the erythrocytes (a type of blood cell that is made in the bone marrow and found in the blood.), salvia and urine.

Is a Magnesium Deficiency Common?

Deficiency of magnesium due to low dietary intake in otherwise healthy people is uncommon.  The kidneys will limit urinary excretion of magnesium to prevent levels from getting too low. 

Some people are at greater risk of magnesium deficiency due to certain conditions. 

People with gastrointestinal diseases who suffer from chronic diarrhea or malabsorption problems may be at greater risk for magnesium deficiencies.  Examples include Crohn’s disease, celiac disease, or surgery of the small intestine.

People with type 2 diabetes may be at greater risk of magnesium deficiency because they may excrete more urine and have more magnesium lost in the urine.  Alcohol dependent people may have poor dietary intake along with more vomiting, diarrhea which can result in higher a chance of magnesium deficiency. 

Older adults may be at greater risk for magnesium deficiency.  Magnesium absorption in the gut decreases and renal excretion increases with age.  Certain medications can also alter the amount of magnesium found in the body. 

Why Do I Need Magnesium?

In the body, magnesium function is often to aid in many processes from enzymes. Magnesium is required for the release and use from the energy yielding nutrients.  Magnesium assists in part of the cellular protein makings. Magnesium is also required to support normal functioning of the immune system, nerve transmission, muscle contraction and heart function.

What are symptoms of deficiency?

Early symptoms of deficiency include loss of appetite, nausea, vomiting, fatigue, confusion and weakness.  As magnesium deficiency worsens, numbness, tingling, muscle, contractions and cramps, seizures, personality changes, abnormal heart rhythms, difficulty in swallowing, hallucinations, and coronary spasms can occur. In severe cases, low serum calcium and potassium levels can occur. 

Is it Possible to Take Too Much?

Toxicity from magnesium is rare. It usually only occurs when taking supplement forms of magnesium. Taking more of any supplement does not mean it is better. Taking too much can cause adverse effects to your health. Symptoms include diarrhea, pH imbalance, or dehydration. Always check with your doctor or registered dietitian nutritionist before taking any supplements.

What if I Do Not Get Enough Magnesium?

Deficiencies are NOT common in HEALTHY people. In the United States dietary surveys show that people consistently consume less than the recommended amount of magnesium.  Approximately, 48% of American consume less the recommended amount of magnesium.  Absorption of magnesium greater when consumed in food rather than in supplement form.  Magnesium supplements come in a variety of forms, including magnesium oxide, citrate and chloride. The amount of magnesium in a supplement is based on the actual amount of magnesium weight found in the supplement not the entire tablet. If you think you do not consistency get enough magnesium in your diet, consult your health care provider for a recommendation. The Recommended Dietary Allowances (RDA) vary by age, sex and pregnancy or lactation status. Below are the recommended amounts.  Getting excessive amount over the RDA is not necessary or recommended.

Always consult your medical professional before starting any supplements. 

Table 1: Recommended Dietary Allowances (RDAs) for Magnesium [1]
Birth to 6 months30 mg*30 mg*
7–12 months75 mg*75 mg*
1–3 years80 mg80 mg
4–8 years130 mg130 mg
9–13 years240 mg240 mg
14–18 years410 mg360 mg400 mg360 mg
19–30 years400 mg310 mg350 mg310 mg
31–50 years420 mg320 mg360 mg320 mg
51+ years420 mg320 mg
*Adequate Intake (AI)
Source: National Institutes of Health Office of Dietary Supplements.

Jacqueline Larson M.S., R.D.N. and Associates