Dietary protein intake, inflammatory biomarkers, genetic susceptibility, and the incidence of sarcopenia: a prospective population-based study

Background: Sarcopenia elevates risks of falls, hospitalization, and mortality in older adults. Despite protein's importance for muscle maintenance, evidence on its overall and source-specific role in sarcopenia development remains inconclusive, particularly regarding interactions with inflammation and genetic factors. Methods: We analyzed data from 37,870 participants in the UK Biobank. Cox proportional hazard models were used to evaluate the association between dietary protein intake and incident sarcopenia. Mediation analyses were conducted to assess whether inflammatory biomarkers mediate the dietary protein intake-sarcopenia association. A polygenic risk score (MetaPRS) for sarcopenia was constructed to explore the joint and interactive effects of dietary protein intake and genetic susceptibility on sarcopenia risk. Results: Higher dietary plant protein intake, but not total or animal protein, was modestly associated with a lower incidence of sarcopenia. Specifically, individuals in the highest intake quartile had a 25% lower risk than those in the lowest (HR = 0.75, 95%CI = 0.58-0.98) in the fully-adjusted model. Mediation analysis suggested that CRP, WBC count, monocyte count, and platelet count to explain 9.9% (95%CI = 4.8-41.5%) of the association, indicating that inflammatory biomarkers may partly contribute to this association. Conclusion: Higher dietary plant protein intake is modestly associated with a lower incidence of sarcopenia, and inflammatory biomarkers may partly contribute to this association.