June 14, 2021

Magnesium and RLS

By Maddie Lionberger, RLS Foundation Research Coordinator

Magnesium is a naturally occurring mineral in our bodies that plays an essential role in a diverse array of biochemical processes, including protein synthesis, muscle and nerve function and blood glucose control. Deficiencies in magnesium can lead to muscle contractions, cramps and problems with conduction of electric signals along nerves. Because of magnesium’s important function in the nervous system, considerable attention has been given to using magnesium supplements to relieve the symptoms of restless legs syndrome (RLS). However, the evidence behind magnesium as an RLS treatment is largely anecdotal. To assess whether taking a magnesium supplement could benefit you, consider the normal values and functions of magnesium and the research as it pertains to RLS.

Magnesium Intake

According to the Office of Dietary Supplements of the National Institutes of Health (NIH) the adult body contains about 25 milligrams (mg) of magnesium. Total magnesium level is tightly regulated by the kidneys, which excrete about 120 mg of magnesium in the urine per day. The Food and Nutrition Board of the National Academy of Medicine recommends an average daily intake of about 240 to 420 mg for men and 240 to 320 mg for women. These recommendations vary by age and sex and are higher during pregnancy. Most people can obtain daily recommended magnesium levels through diet alone – for example, by eating dark green, leafy vegetables such as spinach and kale; nuts and seeds; fish like mackerel and tuna; beans and lentils; avocados; bananas and low-fat or nonfat dairy products. Consuming caffeine, on the other hand, can decrease magnesium levels. Magnesium is also present in dietary supplements and in some medicines, such as antacids and laxatives.

Overall magnesium status is difficult to assess, with 50% to 60% of magnesium present in the bones and the rest mostly in the blood and soft tissues. The most common method for assessing magnesium is by measuring serum magnesium concentration. Normal serum magnesium concentrations range between 0.75 and 0.95 millimoles per liter (mmol/L). Other methods for assessing magnesium status include measuring concentrations in erythrocytes (red blood cells), saliva and urine. However, no single test is considered sufficient without comprehensive laboratory tests and clinical assessment.

Magnesium Deficiency

Symptomatic magnesium deficiency due to low dietary intake is uncommon. Symptoms of deficiency are more likely to arise from excessive losses of magnesium due to certain health conditions and medications. Early signs of magnesium deficiency include loss of appetite, nausea, vomiting, fatigue and weakness. As deficiency worsens, numbness, tingling, muscle contractions and cramps, seizures and personality changes may develop. In severe cases, magnesium deficiency can result in hypocalcemia (low blood calcium) or hypokalemia (low blood potassium). Individuals more likely to be at risk of magnesium inadequacy include those with gastrointestinal diseases such as Crohn’s disease, celiac disease and enteritis (small bowel inflammation); Type II diabetes; or alcohol dependence. Older adults in general are more at risk because they typically consume insufficient amounts of magnesium in their diets or have medical conditions requiring medications that reduce magnesium absorption in the gut.

Supplementation

In the event of a deficiency, magnesium can be taken as a supplement. There are several different doses and forms available, including magnesium oxide, citrate and chloride. Absorption depends on the type of magnesium. Although magnesium oxide is the most commonly available oral supplement, studies reported by the NIH suggest that magnesium in the aspartate, citrate, lactate and chloride forms is absorbed more completely than magnesium oxide or sulfate. Magnesium sulfate can also be administered intravenously (IV), but that method is generally reserved for more severe cases of hypomagnesemia (low levels of magnesium in the blood). The most common use of IV magnesium sulfate is for the prevention of seizures in pregnant women with preeclampsia, eclampsia or toxemia. The Food and Drug Administration recommends against prolonged use of magnesium sulfate; too much magnesium sulfate, or excessive amounts of any supplement for that matter, can be toxic. It is important to consume plenty of fluids while taking magnesium supplements. Consult your doctor before making any changes to your medication regimen.

One of the main roles of magnesium in the nervous system is to block the calcium channel in nerve cells. In other words, magnesium needs to be removed for signaling to occur. Thus, low magnesium levels or magnesium deficiency can result in an over-excited state and eventually cell death of the neuron called excitotoxicity (a pathological process by which neurons are damaged and killed by overactivation). Abnormal neurotransmission of this kind has been implicated in many neurological disorders, including migraine, chronic pain, Alzheimer’s disease and Parkinson’s disease. In a 2018 analysis, "The Role of Magnesium in Neurological Disorders," by Anna E. Kirkland et al., researchers reviewed literature on the role of magnesium in the prevention and treatment of certain neurological disorders. One study showed that high magnesium concentrations were associated with a reduced risk of Parkinson’s disease. However, research examining magnesium levels in people with Parkinson’s has yielded mixed results overall.

Effective for RLS?

With the similarities that RLS and Parkinson’s disease share in pathologies to the dopamine system, it may seem intuitive to try magnesium as a preventive measure for RLS symptoms. However, there is little to no research to support the use of magnesium for idiopathic RLS. Much of the research addressing magnesium and RLS involves symptoms during pregnancy. It is likely that taking magnesium is perceived as an effective therapy for RLS when magnesium deficiency is a contributing factor, i.e., the supplement provides relief for muscle cramps that are easily confused with RLS symptoms. An existing magnesium deficiency may also explain why some individuals report that caffeine triggers their RLS symptoms. If this is the case, it may be beneficial to test magnesium levels. Despite the lack of any scientific correlation with low magnesium levels and RLS, there are many anecdotal reports of people with RLS benefiting from taking magnesium supplements. However, since there is a very strong placebo response for any potential RLS treatment, it is difficult to determine whether these reports truly reflect a benefit for magnesium supplementation and RLS. Large double-blinded medical trials would be necessary to prove that magnesium would be helpful for RLS symptoms.

If you suspect that a magnesium deficiency may be contributing to a worsening of your RLS symptoms, discuss this with your healthcare provider and follow their recommendations and guidelines before making any changes to your medications or supplements.