The Dietary Guidelines for Americans (DGA) provides recommendations for a variety of
“Protein Foods” to meet protein requirements based on “ounce equivalents” (oz-eq). However, no study has evaluated protein sources included in the “Protein Foods Group” of the DGA on an oz-eq basis as part of a meal.


The objective of this study was to assess the effects of consuming 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.


In this single-blinded, randomized crossover study, 30 participants (15 male, 15 female;
Black/African-American: 3; Asian/Pacific Islander: 4; Caucasian: 14; Hispanic/Latino: 9; (age: 26 ± 4.9 y; BMI: 26.4 ± 4.5 kg/m2; mean ± SE) completed four testing sessions where they consumed a standardized test salad on each day with 2 oz-eq of either lean pork, whole eggs, black beans, or almonds. Blood samples were taken at baseline (prior to commencing meal consumption) and at 30, 60, 120, 180, 240, and 300 minutes following the initiation of meal consumption. Plasma from the blood samples were
analyzed for amino acid concentrations via high-performance liquid chromatography (HPLC).


The essential amino acids (EAAs) positive incremental area under the curve (iAUCpos) over 300 minutes for lean pork, egg, black beans, and almonds was 7353 ± 397 μg/mL (least-square mean ± standard error (SE)), 4653 ± 408 μg/mL, 2100 ± 398 μg/mL, and 1220 ± 398 μg/mL, respectively. Pork resulted in signifcantly greater EAAs availability compared to egg, black beans, and almonds (Tukey adjusted, P < 0.0001 for all, while egg resulted in significantly greater EAAs availability compared to black beans and almonds (Tukey adjusted P < 0.0001 for both). No difference for EAAs iAUCpos was
found between black 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,