Animal protein intake is inversely associated with mortality in older adults: the InCHIANTI study

Background: In general, plant protein intake was inversely associated with mortality in studies in middle-aged adults. Our aim was to evaluate the long-term associations of animal and plant protein intake with mortality in older adults. Methods: A prospective cohort study including 1,139 community-dwelling older adults (mean age 75 years, 56% women) living in Tuscany, Italy, followed for 20 years (InCHIANTI study) was analyzed. Dietary intake by food frequency questionnaires and clinical information were assessed five times during the follow-up. Protein intakes were expressed as percentages of total energy. Time-dependent Cox regression models adjusted for confounders were used to assess the association between plant and animal protein intake, and mortality. Results: During the 20-years of follow up (mean: 12y), 811 deaths occurred (292 of cardiovascular- and 151 of cancer-related causes). Animal protein intake was inversely associated with all-cause (HR per 1% of total energy from protein increase, 95%CI: 0.96, 0.93-0.99) and cardiovascular mortality (HR per 1% of total energy from protein increase, 95%CI: 0.93, 0.87-0.98). Plant protein intake showed no association with any of the mortality outcomes, but an interaction with baseline hypertension was found for all-cause and cardiovascular mortality (p<0.05). Conclusions: Animal protein was inversely associated with all-cause and cardiovascular mortality in older adults. Further studies are needed to provide recommendations on dietary protein intake for older adults.