Magnesium Deficiency: The Signs & Symptoms To Look Out For

Magnesium Deficiency: The Signs & Symptoms to Look Out For

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Magnesium influences more than 300 biochemical reactions in the body, helping to support healthy blood sugar, blood pressure, energy production, protein synthesis, and more.* Yet more than 50% of Americans are not getting enough magnesium from their diet, and many experts believe the majority of Americans have subclinical deficiency, which means low magnesium levels without obvious symptoms. 

A magnesium deficiency often goes unnoticed due to seemingly unrelated symptoms and the difficulty of properly testing magnesium levels. If you're concerned about your magnesium levels, here are the most common symptoms of a deficiency, how to test your levels, and what to do about it.

Signs of a magnesium deficiency. 

Magnesium deficiency can be hard to diagnose, especially subclinical deficiency, but if you suffer chronically from two or more of these symptoms, it's a clue that further testing might be needed. Normal serum magnesium levels are defined as 0.75 to 0.95 mmol/L, with anything below this range indicating potential deficiency.

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Fatigue and exhaustion are generalized symptoms. You may attribute your tiredness to stress, poor sleep, or a host of other reasons and not realize just how much nutrition is playing a role. According to research on chronic fatigue syndrome, magnesium provides nutritional support to combat fatigue.* This is because magnesium is required for the production of energy.* If the body has inadequate access to magnesium, then energy production suffers, leaving you prone to fatigue.*

Chronic inflammation

Although inflammation is a necessary part of immune function and wound healing, chronic inflammation underlies many major diseases like heart disease and diabetes. Inflammation can feel like hot and swollen localized areas on the body, generalized aches and pains, overall feeling lousy or tired, or show up as an inflammatory diagnosis. 

Magnesium plays a key role in managing the body's normal inflammatory response.* When magnesium intake is low, inflammatory biomarkers such as high-sensitivity c-reactive protein (hs-CRP), interleukin-6, and fibrinogen are significantly affected.* In fact, a large study of a Nordic diet providing magnesium-rich foods, such as whole grains and vegetables, reduced the pro-inflammatory protein known as Interleukin-1.

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Blood sugar spikes and prediabetes

Although blood sugar (glucose) levels are no doubt heavily influenced by what you eat and how much energy you expend, surprisingly they are also influenced by magnesium levels. This is because magnesium assists the body in glucose and insulin metabolism.* 

A large six-year study found that low serum magnesium levels were associated with insulin resistance and risk of prediabetes.* In addition, it found that common variations in magnesium-regulating genes that cause low serum magnesium were associated with increased risk for diabetes.*  Unfortunately, the onset of diabetes might compound the problem because it increases urinary magnesium excretion.

Restless leg syndrome and leg cramps

Although the mechanisms aren't well understood, there is anecdotal and some limited published evidence that low magnesium levels can cause restless leg syndrome (RLS). 

Magnesium supplementation has been found to help manage symptoms of RLS, leg cramps, and even periodic limb movement disorders.* Magnesium might be most beneficial in muscle cramps related to pregnancy;* however, more research is needed.

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Stress and mood swings

More than 40 million Americans' quality of life is affected by their daily struggles with social stress, fear, and apprehension. Maintaining normal magnesium levels could help manage stress due to magnesium's beneficial interaction with the brain.* 

Magnesium is important for the regulation of the "feel-good" neurotransmitters dopamine and serotonin as well as the stress response.* In other words, low brain magnesium means serotonin levels are reduced, which can present as mood swings.* Studies back this up, showing that low levels of magnesium intake are associated with mood disorders.*

Migraines and headaches

Migraines are the sixth-most disabling illness worldwide, causing hours and days of recurring pain, sensitivity to light and sound, and even nausea and vomiting. A large body of evidence has found that magnesium, whether administered orally or via IV, can be an effective and inexpensive option for providing nutritional support in the management of migraines.*

Although the mechanisms aren't fully understood, it is known that maintaining a normal magnesium level helps preserve the electrical function of brain neurons.*

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Irregular heartbeat or rhythm

Magnesium is a mineral and electrolyte that the body requires to maintain normal nerve and electrical impulses of the heart.* Heart flutters, elevated or slow heart rate, and a "racing" heartbeat are all signs of a possible magnesium deficiency.* 

In addition, reduced magnesium intake, as well as low serum levels, have been shown to have an adverse effect on multiple aspects of cardiovascular health.* According to a meta-analysis, an extra 100 mg of magnesium a day in the diet was associated with cardiovascular health.*

How to test your magnesium levels.

Although severe magnesium deficiency is rare, subclinical deficiency is much more common. If you are concerned about your magnesium level, there are several lab tests you can discuss with your health care provider.

A serum magnesium blood test can be obtained with a quick and simple blood draw, although it can be a poor indicator of magnesium levels because 99% of magnesium resides within your cells and tissue.

Urinary magnesium excretion, obtained via a 24-hour urine collection, might be a more accurate assessment tool, but it can be cumbersome. A magnesium retention (or "loading") test is also more reliable than blood testing but requires measurement of bone magnesium after an oral or IV magnesium dose.

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How to get sufficient magnesium.

Most people need between 300 and 420 mg of magnesium per day, with men on the higher end. Here is the recommended dietary intake of magnesium for adults:

  • Men, 19-30 years: 400 mg
  • Women, 19-30 years: 310 mg 
  • Men, 31+ years: 420 mg
  • Women, 31+ years: 320 mg
  • Pregnant women: 350-400 mg
  • Breastfeeding women: 310-360 mg

Several foods are exceptional sources of magnesium, but especially dark leafy greens, nuts, seeds, legumes, and whole grains. Here are a few magnesium powerhouse foods that deserve to become staples in your diet: 

  • Pumpkin seeds (raw), ¼ cup = 191 mg
  • Spinach or Swiss chard (raw), 1 cup = 150-156 mg
  • Soybeans (cooked), 1 cup = 148 mg
  • Black beans (cooked), 1 cup = 120 mg
  • Quinoa (cooked), ¾ cup = 118 mg
  • Cashews (raw), ¼ cup = 116 mg
  • Sesame or sunflower seeds, ¼ cup = 113-126 mg


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Magnesium is also available as a nutritional supplement in tablet and capsule form, or in creams, sprays, bath salts, and powders. There are several different forms of supplemental magnesium, but the glycinate, citrate, chloride, lactate, and aspartate forms are best absorbed by the body. 

Side effects can include diarrhea, especially with the oxide and chloride forms, and toxicity can develop. The Food and Nutrition Board's tolerable upper limit for magnesium supplementation is 350 mg per day, unless treating a known deficiency.

The take-aways.

Magnesium is an important mineral that protects our organs, DNA and cell integrity, helps our bodies produce energy, helps maintain the body’s normal inflammatory responses, and supports normal blood pressure and blood sugar levels.*  

Despite several delicious and easy-to-eat foods that supply ample magnesium, like nuts, seeds, beans, dark leafy greens, and whole grains, supplementation may be ideal.

If you suffer chronically from any of the symptoms listed above, then magnesium supplementation could be beneficial.* Aim to consume 300 to 420 mg of magnesium per day from a combination of food and supplements, or more for a diagnosed deficiency.

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