Body composition changes as people get older. One of the noteworthy alterations is the reduction in total body protein. According to PubMed.gov “Protein and older adults” publication, the protein tissue accounts for 30% of whole-body protein turnover but that rate declines to 20% or less by age 70. The importance of dietary protein cannot be underestimated in the diets of older adults; inadequate protein intake contributes to a decrease in reserve capacity, increased skin fragility, decreased immune function, poorer healing, and longer recuperation from illness.
(J Am Coll Nutr. 2004 Dec;23(6 Suppl):627S-630S.)