Association of dietary protein intake with accelerated biological aging markers and all-cause mortality in adults

BACKGROUND: Aging processes could be influenced by diet. However, the extent to which dietary protein intake is associated with biological aging (BA) markers remains poorly characterized. OBJECTIVES: Here, we evaluated the association between dietary protein intake and BA markers and explored the extent to which BA markers mediate the association between protein intake and all-cause mortality. METHODS: We analyzed data from NHANES cycles 1999-2000 and 2001-2002. Dietary protein intake was expressed in g/kg/day. BA was estimated with TL, AnthropoAge, PhenoAge, and the Klemera-Doubal Method (KDM). Accelerated aging was defined as TL <25th percentile of the weighted population distribution and as residuals from BA markers regressed against CA. Survey-weighted logistic and linear regression models were fitted. Mortality correlates were evaluated using cause-specific Cox proportional hazards models and mediation analyses. RESULTS: Among 6,249 adults (median age: 45 [IQR: 34-58], 52% women), we found that participants in the highest protein intake quintile (>1.40 g/kg/day) had a lower adjusted likelihood of having accelerated aging by TL (OR: 0.40, 95% CI: 0.22-0.73), PhenoAge (OR: 0.54, 95% CI: 0.32-0.92), and KDM (OR: 0.53, 95% CI: 0.32-0.87), compared with those in the lowest quintile (<=0.62 g/kg/day). Higher dietary protein intake was associated with a lower hazard of all-cause mortality, and BA metrics partially mediated these associations. CONCLUSIONS: Higher dietary protein intake was associated with a lower likelihood of accelerated aging and reduced mortality, with the latter association partially mediated by BA markers. Our findings suggest that dietary protein intake could influence healthy aging.