• Higher dietary magnesium intake is significantly associated with reduced cardiovascular disease mortality in osteoarthritis patients, with a 78% risk reduction per unit increase.
• Dietary magnesium intake exhibits a U-shaped association with all-cause and cancer mortality, with optimal intake thresholds at 0.38 g/d and 0.40 g/d, respectively.
• Both low and high magnesium intake increase mortality risk, emphasizing the importance of maintaining adequate but not excessive magnesium levels.
• Subgroup analyses confirm the robustness of these findings, supporting the role of magnesium in nutritional management for osteoarthritis patients.