Animal and Plant Protein Usual Intakes are Not Adversely Associated with All-Cause, Cardiovascular Disease- or Cancer-Related Mortality Risk: An NHANES III Analysis.

We used data from NHANES 1988-1994 to examine associations between animal and plant protein usual intakes and IGF-1 concentration with mortality from all causes, cancer, and cardiovascular disease (CVD). Adult data (N=15,937) were linked with mortality data (N=3,843 events) through 2006. Usual intakes for protein were estimated using the multivariate Markov Chain Monte Carlo method. Hazard ratio (HR) models were fit for mortality types (all-cause, cancer, and CVD) with protein intake measures (per 1g increase) and IGF-1 concentration (N=5753). There were no associations between animal protein (HR=0.99; 95% confidence interval [CI]: 0.98-1.01; P=0.29) or plant protein (HR=1.02; 95% CI: 0.95-1.10; P=0.55) intake for all-cause mortality. Similar results were seen for CVD mortality and animal protein (HR=1.02; 95% CI: 0.99-1.04; P=0.14) and plant protein (HR=1.01; 95% CI: 0.91-1.13; P=0.81). There was an (inverse) association between cancer mortality and animal protein (HR=0.95; 95% CI: 0.91-1.00; P=0.04) but no relationship with plant protein (HR=1.08; 95% CI: 0.93-1.24; P=0.30). We found no association between concentrations of IGF-1 (N=5,753) for all-cause mortality (HR=1.00; 95% CI: 0.99-1.00; P=0.81), CVD mortality (HR=0.99; 95% CI: 0.99-1.00; P=0.53) or cancer mortality (HR=1.00; 95% CI: 0.99-1.00; P=0.76). Our results remained unchanged when the sample was separated into younger (<65yr) and older (>65, or between 50-65yr) cohorts. Our data do not support the thesis that source-specific protein intake is associated with greater mortality risk; however, animal protein may be mildly protective for cancer mortality. Mortality risk was not associated with circulating IGF-1 in any age group.