Protein Nutritional Status and Frailty: A Mendelian Randomization Study

Abstract

BackgroundObservational studies have suggested that better protein nutritional status may contribute to prevention of frailty. ObjectiveWe sought to examine this hypothesis using a Mendelian randomization (MR) analysis. MethodsWe conducted a two-sample MR study using GWAS summary statistics data of the UK Biobank. We applied genetically predicted serum albumin as a primary exposure measure and serum total protein as a secondary exposure measure. The outcome measure was the Rockwood frailty index (FI) based on 49 deficits from 356,432 individuals (53.3% of them were women, with a mean ± SD age of 56.7 ± 8.0 y. The association between serum protein measures and FI was mainly analyzed by use of the inverse variance weighted method. ResultsA genetically predicted serum albumin concentration was not statistically significantly associated with FI in the full sample. However, in women, we observed a preventive association between genetically predicted serum albumin and FI (β = −0.172 per g/L; 95% CI: −0.336, −0.007; P = 0.041). In the full sample, genetically predicted serum total protein was inversely associated with FI (β: −0.153 per g/L; 95% CI: −0.251, −0.056; P = 0.002). In both women and men, higher serum total protein was significantly inversely associated with FI; regression coefficients were −0.148 per g/L (95% CI: −0.287, −0.009; P = 0.037) for women, −0.154 per g/L (95% CI: −0.290, −0.018; P = 0.027) for men. ConclusionsThe present MR study implies that better protein nutritional status modestly contributes to reducing the risk of frailty.