Causal relationships between micronutrients and sarcopenia: a two-sample bidirectional Mendelian randomization study

Sarcopenia, a geriatric syndrome in older adults, significantly impacts quality of life and elevates health risks. This study examines the causal relationships between specific micronutrients—magnesium, selenium, calcium, zinc, iron, phosphorus, and omega-3 fatty acids—and sarcopenia-related traits (SP-traits) using Mendelian randomization (MR) based on genome-wide association studies (GWAS). A bidirectional two-sample MR analysis was performed using data from fourteen GWAS, focusing on five SP-traits: low hand grip strength, moderate-to-vigorous physical activity (MVPA), ability to walk or cycle unaided for 10 min (AWCU10), usual walking pace, and adjusted appendicular lean mass (ALM). The analysis identified 14 single nucleotide polymorphisms (SNPs) linked to zinc levels and MVPA, and 12 SNPs associated with usual walking pace. Concerning ALM, 72 SNPs were associated with magnesium and 81 with omega-3 fatty acids. Significant associations were noted between zinc levels and MVPA (beta = 0.85, P = 0.026) and usual walking pace (beta = 0.53, P = 0.008). The reverse MR analysis revealed a positive correlation between ALM and magnesium (beta = 0.126, P = 0.0004) and a nominally significant negative correlation with omega-3 (beta = -0.083, P = 0.008). While some heterogeneity was noted, no pleiotropy was detected, reinforcing the robustness of the findings. This study highlights the importance of magnesium, zinc, and omega-3 fatty acids in muscle health and advocates for their inclusion in public health strategies to enhance the physical function and quality of life in older adults. Further research is needed to validate these findings across diverse populations.