Causal relationship between dietary habits and low hand grip strength

A large number of studies have shown a close association between dietary habits and low hand grip strength. However, the presence of a causal connection between dietary habits and low hand grip strength remains unclear. All genome-wide association studies of dietary habits summary statistics were run in BOLT-LMM software (Broad Institute) using linear mixed models with 10 genetic principal components and genotyping array as covariates, and all phenotypes were averaged over multiple Food Frequency Questionnaires, adjusted for age and sex, and inverse normal transformed. The extracted single nucleotide polymorphisms explored the relationship between dietary habits and low hand grip strength by inverse variance weighted (IVW), Mendelian randomization-Egger (MR-Egger), and MR-pleiotropy residual sum and outlier. IVW estimates indicated that different dietary habits had a causal association with low hand grip strength, including drinking currently with various meals (beta: -0.432, 95% confidence interval [CI]: -0.669 to -0.194, PIVW = 3.70E-04), semi-skimmed milk (beta: -0.825, 95% CI: -1.626 to -0.024, PIVW = 4.30E-02), flora and benecol spread (beta: 0.210, 95% CI: 0.037-0.382, PIVW = 1.80E-02), tablespoons of raw vegetables per day (beta: -0.361, 95% CI: -0.563 to -0.158, PIVW = 4.80E-04), no dairy restrictions (beta: 1.223, 95% CI: 0.372-2.074, PIVW = 4.90E-03) and no eggs, dairy, wheat, or sugar restrictions (beta: 1.027, 95% CI: 0.377-1.677, PIVW = 2.00E-03). All significant MR results are false discovery rate-corrected. This MR investigation revealed that various dietary habits were causally linked to low hand grip strength. Further investigations into their relationships are necessary and will contribute to preventing low hand grip strength.