Magnesium and Fibromyalgia
Magnesium is one of the most abundant minerals in the body. Roughly half of all body stores of magnesium are found in the bone, with the remaining half located inside body tissues and organs, and approximately 1% in the blood. Magnesium is essential for over 300 processes that occur in the body. These include maintenance of normal muscle and nerve function, regulation of heart rhythm, immune system support, bone strength, and energy metabolism.
Magnesium is most abundant in foods such as green leafy vegetables, nuts, beans, legumes, and grains in which the outer layers have not been removed. Although a balanced diet normally supplies all of the magnesium an individual requires, diets high in fat may impair the body’s ability to absorb magnesium. In the United States, the recommended dietary allowance, or RDA, for adolescent and adult females is between 280-300 milligrams (mg) of magnesium per day. The RDA for adolescent and adult males ranges from 270-400 mg.
Because magnesium is absorbed in the intestines and excess magnesium is excreted though the kidneys, the health status of the digestive system and kidneys have a large impact on an individual’s magnesium status. As a result, individuals with certain gastrointestinal disorders, such as Chrohn’s disease, may have an impaired ability to absorb magnesium and therefore be deficient. In addition, individuals who have decreased kidney function due to alcohol abuse or uncontrolled diabetes may also experience magnesium deficiency. Early symptoms of magnesium deficiency may include appetite loss, nausea, vomiting, fatigue, and weakness. As the degree of magnesium deficiency increases, individuals may experience numbness, tingling, muscle cramps, muscle weakness, irritability, seizures, personality changes, and abnormal heart rhythms.
Consuming magnesium in adequate quantities through diet alone does not pose any significant health risks; however, there are side effects associated with excess magnesium supplementation, including diarrhea and abdominal cramps. Individuals with impaired kidney function are at an increased risk of magnesium toxicity because their kidneys do not have the adequate ability to remove excess magnesium. In addition, extremely large doses of magnesium-containing laxatives and antacids have also been known to cause magnesium toxicity. The signs of magnesium toxicity can include some of those associated with its deficiency, such as fainting, dizziness, flushing, muscle paralysis, and difficulty breathing. Symptoms of overdose, which is relatively rare in individuals who have normal kidney functioning, including vision disturbances, coma, dizziness, severe drowsiness, increased/decreased urination, decreased heart rate, and breathing difficulties.
Research on Magnesium and Fibromyalgia
Research has demonstrated that supplemental magnesium may be useful to treat the symptoms associated with several comorbid conditions that are common among fibromyalgia patients. For those with irritable bowel syndrome and other disorders of the digestive system, magnesium-containing laxatives are useful to relieve constipation (Anderson & Knoben, 1997). Muscular injections of magnesium have also been shown to improve symptoms associated with chronic fatigue syndrome (CFS) in CFS patients who have low concentrations of magnesium in their red blood cells (Cox et al., 1991). However, the usefulness of this intervention is suspect in light of other research that suggests a majority of CFS patients have normal magnesium stores, as well as confounded by the fact that red blood cell magnesium levels are generally considered to be poor markers for body magnesium (Young & Trimble, 1991). Further evidence suggests that there may be some benefit to magnesium supplementation as a means of treating both cluster headaches and migraine, although the findings are mixed (Mauskop et al., 1995a; Mauskop et al., 1995b; Peikert et al., 1996; Demirkaya et al., 1996; Pfaffenrath et al., 1996; Maizels et al., 2004). Finally, a number of women with fibromyalgia also suffer from severe symptoms associated with premenstrual syndrome (PMS), and some research shows that magnesium supplementation can improve symptoms in individuals with PMS (Bendich, 2000; Facchinetti et al., 1991a; Facchinetti et al., 1991b; Walker et al., 1995).
The role, if any, that magnesium deficiency plays in fibromyalgia itself has yet to be determined. A number of research studies have been conducted and collectively they report conflicting findings. For example, early research into the association between magnesium deficiency and fibromyalgia found normal blood levels of magnesium in patients (by Prescott et al., 1992). Later research by Rosborg et al. (2007) also confirmed these findings. Conversely, other early research by Eisinger et al. (1994) found that patients with fibromyalgia had lower magnesium and selenium levels than age-matched controls, although this study was likely limited by a small sample size (22 fibromyalgia patients, 23 controls). In a study similar to the recent study by Sakarya et al. described below, Sendur and colleagues examined the relationship between selenium, zinc, and magnesium levels and clinical parameters (pain, sleep, functioning, etc.) among 32 fibromyalgia patients and 32 controls. Their findings showed statistically significant differences between the zinc and magnesium levels of fibromyalgia patients when compared to controls, with fibromyalgia patients having lower levels of both minerals. From their findings, they authors hypothesized that zinc and magnesium deficiency might play a role in the development of fibromyalgia and emphasize the need for further research into the matter (Sendur et al., 2008).
More recent research has continued to provide conflicting findings related to the impact and incidence of magnesium deficiency among fibromyalgia patients. A 2011 study used hair sample analysis to compare mineral levels between female fibromyalgia patients and healthy controls. For the purposes of the study, 44 female patients (ages 29-57) with fibromyalgia and 100 control subjects were asked to donate 300 mg of hair from four to five locations on the back of their head. The results of the hair mineral analysis showed statistically significant differences in the levels of calcium, magnesium, copper, iron, and manganese between the control subjects and fibromyalgia patients, with fibromyalgia patients consistently demonstrating lower levels of all minerals. In their discussion of the findings, the authors cite the importance of magnesium’s role in neuromuscular function and its relationship to muscle weakness and cramps, and suggest further investigation to determine how magnesium supplementation may impact the progress of fibromyalgia (Kim Y-S, et al., 2011).
Another recent study also investigated magnesium levels in fibromyalgia patients. This case-control study evaluated blood levels of the antioxidant vitamins A, C, and E, as well as magnesium in 40 female fibromyalgia patients and 40 healthy control subjects. All patients provided demographic information, and their accompanying symptoms (such as morning stiffness, sleep disturbances, anxiety, Raynaud’s, and irritable bowel syndrome) were also documented. Each patient was examined to determine their level of widespread chronic pain, number of tender points, degree of functional capacity, and level of depression. Following the analysis, the researchers found no statistically significant differences in levels of magnesium, or vitamins A, C, and E between the fibromyalgia patients and the controls. In addition, the researchers were not able to detect any relationship between levels of these vitamins and the number of tender points, pain severity, functional status, and depression among the fibromyalgia patients. In their discussion, the authors suggest that perhaps differences in analytic methods may explain the divergent findings between studies that have investigated an association between magnesium and fibromyalgia. Similar to other researchers in the field, they cite the need for continued research through clinical trials designed to measure and evaluate blood levels of magnesium and vitamins in fibromyalgia patients. They also point out the importance of including large numbers of patients in future studies, as well as subjects of both sexes. In doing so, they note that their current was limited by a small sample of all-female patients (Sakarya et al., 2011).