Causal associations of plasma omega-3 polyunsaturated fatty acids with sarcopenia-related traits: a two-sample Mendelian randomization study

Objective To evaluate the causal effect of plasma omega-3 polyunsaturated fatty acids (PUFAs) on sarcopenia-related traits (lean mass, grip strength and walking pace) utilizing two-sample Mendelian randomization (MR) approach. Methods Based on genome-wide association study (GWAS) summary statistics, we performed two-sample MR applying the inverse variance weighted (IVW) as the primary method, supplemented with four additional sensitivity analyses. Furthermore, multivariable MR (MVMR) was applied to assess these associations independent of alcohol drinking, type 2 diabetes (T2D), triglycerides (TG), estimated glomerular filtration rate (eGFR) and C-reactive protein (CRP). Results In univariable MR, the IVW analysis suggested no significant causal effect of genetically determined plasma omega-3 PUFAs on fat-free mass (right leg: β = 0.01, 95% CI = −0.02 to 0.05, P = 0.375; left leg: β = 0.01, 95% CI = −0.02 to 0.04, P = 0.446; right arm: β = 0.01, 95% CI = −0.02 to 0.05, P = 0.376; left arm: β = 0.01, 95% CI = −0.02 to 0.04, P = 0.384; trunk:β = 0.02, 95% CI = −0.02 to 0.06, P = 0.283; whole: β = 0.01, 95% CI = −0.03 to 0.04, P = 0.631), grip strength (right hand: β = −0.01, 95% CI = −0.03 to 0.01, P = 0.387; left hand: β = −0.01, 95% CI = −0.02 to 0.01, P = 0.553) and walking pace (β = 0.00, 95% CI = −0.01 to 0.02, P = 0.575), and sensitive analysis generated similar non-significant results. Furthermore, the MVMR revealed no independent causal association. Conclusions Genetically determined plasma omega-3 PUFAs have no causal effect on sarcopenia-related traits.