Protein intake and risk of mortality: Findings from the InCHIANTI study

The importance of maintaining adequate protein intake is well documented in older adults, although insufficient protein consumption is common in this age group. Beyond strictly assessing quantity, the impacts of different sources of protein (animal vs. plant-based) may also be of interest in optimizing health outcomes.

Group de gens plus agés qui mangent autour d`une table dehors

A 2021 prospective cohort study assessed the association between different sources of protein (animal vs. plant) and certain mortality outcomes (all-cause, cardiovascular, and cancer) in a sample of 1 139 older adults (65 years +) in the Chianti region of Italy. Researchers used the findings of a 240-item food frequency questionnaires administered 5 times over a 20-year follow-up period to assess dietary intakes. Protein intake was measured as a percentage of total energy. Different models were generated in the analysis to consider potential confounding factors, such as demographic characteristics, chronic health issues, diet quality, and smoking.

Overall, study participants consumed an average of 74 grams of protein per day (1.1 g/kg body weight), out of which 63% was supplied by animal sources. Compared with the lowest quintile, participants in the highest quintile of total protein intake consumed more meat, dairy, fish, and seafood. Sources of animal protein were dairy products (26%), processed meats (26%), red meat (20%), fish and seafood (7.7%), chicken (6.3%), eggs (2.7%), and the rest for other meats. In contrast, the main sources of plant proteins were cereal (73%), vegetables (11.4%), fruit and nuts (9.0%), and legumes (5.3%). 

After the 20-year follow-up, 811 deaths occurred (292 due to cardiovascular disease, 151 due to cancer). In the fully adjusted model, higher total protein intake was inversely associated with cardiovascular mortality, although no association was detected for cancer or all-cause mortality risks. Conversely, every 1% increase in animal protein intake was linked to 4% and 7% decreases in risks of all-cause mortality and cardiovascular mortality, respectively. No association was detected for plant proteins for cardiovascular, cancer, or all-cause mortality outcome.

The findings of this study highlight the potential beneficial role of increased total and animal-based protein intake on health. Authors hypothesize that this may be due in part to the protective role of animal protein against frailty, immune response, and sarcopenia. Moreover, they note that many acute or chronic inflammatory conditions may increase protein requirements to maintain muscle strength in older adults.

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