The causal relationships between iron status and sarcopenia in Europeans: a bidirectional two-sample Mendelian randomization study

Previous studies have indicated potential associations between metals, lifestyle factors, and sarcopenia. However, the specific causal relationships between iron status, lifestyle factors, and sarcopenia remain unclear. Therefore, we conducted a bidirectional two-sample Mendelian Randomization (MR) approach to investigate these relationships.

The exposure variables included iron status, living alone, coffee intake, alcohol taken with meals, and moderate physical activity, while the outcome variable was sarcopenia, assessed by grip strength in both hands and usual walking pace. We employed the Weighted Median (WM), the Inverse Variance-Weighted (IVW), and other MR methods to explore these problems for analysis. Simultaneously, we conducted a bidirectional MR analysis to assess whether sarcopenia has a reverse causal relationship with internal iron status.

In our present research, we found serum iron (P = 0.033), ferritin (P = 0.001), transferrin saturation (P = 0.029) and coffee intake (P = 0.002) revealed a negative trend for sarcopenia, living alone (P = 0.022) and alcohol taken with meal (P = 0.006) showed a opposite trend for sarcopenia. Whereas sarcopenia showed negative trend for ferritin (P = 0.041) and transferrin saturation (P = 0.043), showed the opposite trend for transferrin (P = 0.021).

Our study suggested that higher serum iron levels might reduce the risk of sarcopenia. Moreover, living alone and alcohol consumption might increase the sarcopenia risk, while coffee intake and moderate physical activity could reduce the sarcopenia risk.