Obstructive sleep apnea (OSA) is a prevalent disorder posing significant health hazards. Studies have suggested an association between trace elements and OSA; however, the causal relationship of this association remains unclear.

This study investigated the potential causal relationship between magnesium and OSA, with magnesium status evaluated through magnesium-related single nucleotide polymorphisms (SNPs) and magnesium depletion score (MDS). Mendelian Randomization (MR) and the National Health and Nutrition Examination Survey (NHANES) were used to mitigate confounders and ensure a more robust assessment.

MR analysis indicated a significant protective effect of magnesium against OSA (odds ratio [OR]<1, P < 0.05). A reverse MR analysis of OSA on magnesium did not show significant causal effects (P > 0.05). NHANES analysis further demonstrated a strong positive correlation between MDS and OSA, with participants scoring above 1 exhibiting a 64 % increased likelihood of developing OSA (OR = 1.64, 95 % confidence interval [CI]: 1.32–2.05, P < 0.001). Adjusted multivariable logistic regression models confirmed the robustness of this association (Model II: OR = 1.36, 95 % CI: 1.08–1.72, P = 0.018; Model III: OR = 1.30, 95 % CI: 1.03–1.63, P = 0.045). Subgroup and interaction analysis revealed no statistically significant interactions (P > 0.05).

We confirmed the causal relationship between magnesium and OSA, underscoring magnesium's role in OSA pathogenesis and suggesting that MDS may serve as a promising biomarker for identifying high-risk populations. Further studies on the biological mechanisms linking magnesium deficiency to OSA may contribute to its treatment.