Strongest evidence: The most robust research supports magnesium for reducing depression symptoms, with moderate evidence strength. All 3 studies (including 1 meta-analysis and 1 systematic review) reported small beneficial effects. However, no consistent dose, form, or duration data were available, and the evidence base is small, with potential publication bias noted.
Mixed or weaker evidence: For reducing C-reactive protein (CRP) levels, evidence is low strength. Of 3 studies, 2 reported beneficial effects (small to moderate effect sizes) in populations with metabolic syndrome or overweight/obesity, while 1 study found no effect. The beneficial studies were systematic reviews, but one co-administered magnesium with vitamin D, making the independent effect unclear. The neutral study used a low dose (150 mg/day) of magnesium hydroxide, which may not reflect typical supplementation.
Effective dose patterns: No consistent effective dose emerged across outcomes. For CRP reduction, effects were observed at a median study duration of ~12 weeks, but specific dose ranges were not reported. For depression, dose data were largely missing. This limits dose-response conclusions.
Population insights: For CRP reduction, beneficial effects were seen in clinical populations with metabolic syndrome or overweight/obesity. No specific populations were identified for depression outcomes. No data were available on deficient vs. replete populations.
Notable caveats: The evidence base for both outcomes is small (3 studies each), making conclusions preliminary. For depression, publication bias may inflate positive findings. For CRP, one beneficial study co-administered magnesium with vitamin D, confounding the independent effect. Dose, form, and duration data were largely missing across studies, preventing dose-response analysis.