Magnesium malate has been investigated for its potential role in supporting Fibromyalgia Syndrome (FMS), a chronic condition characterized by widespread pain, fatigue, and sleep disturbances. The rationale for its use is based on two factors: magnesium's involvement in muscle and nerve function, and malic acid's role in energy production within the mitochondria. Some researchers hypothesize that magnesium deficiency or mitochondrial dysfunction may contribute to fibromyalgia symptoms, and that supplementation could help alleviate them.

Several small-scale studies and pilot trials have explored magnesium and magnesium malate supplementation in FMS patients. For example, a 1995 open-label study by Russell et al. suggested that magnesium malate (1,200-2,400 mg daily) might reduce pain and tenderness in some fibromyalgia patients over an 8-week period. However, the study lacked a placebo control and had a small sample size, limiting the reliability of the results. Other studies on magnesium alone have shown mixed findings, with some indicating potential symptom improvement and others showing no significant effect.

Systematic reviews generally conclude that the evidence supporting magnesium malate for fibromyalgia is weak and insufficient for firm recommendations. Most clinical guidelines do not endorse its routine use for FMS. In summary, while there is some scientific rationale and limited preliminary research, robust clinical evidence is lacking, and further well-designed trials are needed to determine efficacy.