The 2015-2020 Dietary Guidelines for Americans (DGA) recommends how much protein-rich foods should be consumed as part of Healthy Eating Patterns. The predominant protein sources include lean meats, poultry, and eggs, along with nuts, seeds, and soy products (dairy is a separate category). Ounce-equivalent (oz-eq) is used as a standard unit of measure among these protein sources. One whole egg (1 oz-eq) is equal to 0.5 oz of nuts (1 oz-eq), 0.25 c (1 oz-eq) of beans, and 1 oz of lean meat (1 oz-eq). Importantly, protein quantity and quality of the foods are not considered. Consequently, consuming an oz-eq of protein foods from different sources may have different effects on an individuals' digestion, absorption, and use of the amino acids contained in proteins to build new proteins in their body (an anabolic response to feeding). Also importantly, while the current Recommended Dietary Allowance for protein (0.8 g total protein/kg/d) does not take into account the sources of protein consumed, these sources have varied essential amino acid patterns. The purpose of this study is to expand on a recent study assessing the effect of consuming ounce-equivalents of eggs versus pork, nuts, and beans on essential amino acid (EAA) substrate availability for protein anabolism in younger adults to include a cohort of older adults. Findings from this current research will allow direct comparisons of postprandial EAA substrate availability between different protein-rich food sources in a cohort of older adults (primary outcome). Subsequently, investigating postprandial responses of the same ounce-equivalents of fresh pork versus nuts, beans, and eggs on postprandial plasma essential amino acid availability in older adults will also allow for a comparison between the younger (from a study started prior to this one and still currently ongoing investigating the effect of the same ounce-equivalents of fresh pork versus nuts, beans, and eggs on postprandial plasma essential amino acid availability in adults) and older adult cohorts response to consuming different protein-rich foods (secondary outcome). This research will serve as an important resource for future DGA Committees to assess whether 'protein-ounce-equivalents' of varied protein-rich foods provide equivalent EAA substrate to promote postprandial protein synthesis in older adults, in support of dietary protein intake recommendations for younger and older adults.
This study will determine the effect of the same ounce-equivalents of fresh pork versus nuts, beans, and eggs on postprandial plasma essential amino acid availability in older adults. Each participant will receive all four treatments.