The Dietary Guidelines for Americans (DGA) recommends consuming a
variety of “Protein Foods” based on “ounce-equivalent” (oz-eq) portions. No study has assessed the same oz-eq portions of animal- vs. plant-based protein foods on essential amino acid (EAA) bioavailability for protein anabolism in young and older adults


The objective of this study was to assess the effects of consuming two ounce equivalent portions of fresh pork versus nuts, beans, and eggs, as defined by the DGA, as part of a meal, on essential amino acid substrate availability for protein anabolism in young adults.


Two investigator-blinded, randomized crossover trials were conducted in young and older adults. Participants completed four testing sessions where they consumed a
standardized meal with two oz-eq of either unprocessed lean pork, whole eggs, black beans, or sliced almonds. Blood samples were taken at baseline and 30, 60, 120, 180, 240, and 300 min postprandially. Plasma EAA bioavailability was based on postprandial integrated positive areas under the curve


Participant age did not affect EAA bioavailability among the four protein foods tested. Two oz-eq portions of pork (7.36 g EAA) and eggs (5.38 g EAA) resulted in greater EAA bioavailability than black beans (3.02 g EAA) and almonds (1.85 g EAA) in young and older adults, separately or combined (p < 0.0001 for all). Pork resulted in greater EAA bioavailability than eggs in young adults (p < 0.0001), older adults (p = 0.0007), and combined (p < 0.0001). There were no differences in EAA bioavailability between black beans and almonds.


This research serves as an important resource for future Dietary Guidelines Advisory
Committees to reevaluate the appropriateness of equating Protein Foods on the current ounce-equivalent basis. Animal-derived protein-rich foods, including fresh lean pork and whole eggs, are excellent sources of amino acids needed to build new proteins in a person’s body

For additional information contact Wayne W. Campbell, Ph.D., Professor, Department of Nutrition Science, Purdue University, 765-494-8236, [email protected].


Nutrients: Effects of Consuming Ounce-Equivalent Portions of Animal- vs. Plant-Based Protein Foods, as Defined by the Dietary Guidelines for Americans on Essential Amino Acids Bioavailability in Young and Older Adults: Two Cross-Over Randomized Controlled Trials