Gavin Connolly, Joshua L Hudson, Robert E Bergia, Eric M Davis, Austin S Hartman, Wenbin Zhu, Chad C Carroll, Wayne W Campbell
Journal: Nutrients 2023;15(13):2870
PMID: 37447197
Dietary protein is essential for building and maintaining muscle. When it is consumed, it is broken down into its constituent parts, known as amino acids. Some amino acids can be synthesised in the body, however there are some that cannot, these are known as essential amino acids (EAAs), and these must come from the diet. Animal-based protein foods contain all the EAAs required by humans, whereas plant-based foods do not. Animal-based and plant-based foods may also differ as sources of protein, due to differences in how easily the body can use the EAAs the protein contains, this is known as bioavailability. This randomised control trial of 37 individuals aimed to determine any differences in bioavailability between animal-based and plant-based foods and whether age may influence response. The results showed that age did not affect the bioavailability of animal-based and plant-based proteins. However, the EAAs from pork and eggs were shown to be more bioavailable than almonds and black beans. Pork was more bioavailable than eggs, however there were no differences in bioavailability of black beans and almonds. It was concluded that animal-based foods are a more bioavailable form of EAAs than plant-based foods and that pork EAAs were the most bioavailable out of the foods analysed. This study could be used by healthcare professionals to understand that people on a plant-based food only diet may be deficient in certain EAAs, which may require supplementation.
BACKGROUND
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.
OBJECTIVES
We assessed the effects of consuming two oz-eq portions of pork, eggs, black beans, and almonds on postprandial EAA bioavailability in young and older adults.
METHODS
We conducted two investigator-blinded, randomized crossover trials in young ( = 30; mean age ± SD: 26.0 ± 4.9 y) and older adults ( = 25; mean age ± SD: 64.2 ± 6.6 y). 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.
RESULTS
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 ( < 0.0001 for all). Pork resulted in greater EAA bioavailability than eggs in young adults ( < 0.0001), older adults ( = 0.0007), and combined ( < 0.0001). There were no differences in EAA bioavailability between black beans and almonds.
CONCLUSIONS
The same "oz-eq" portions of animal- and plant-based protein foods do not provide equivalent EAA content and postprandial bioavailability for protein anabolism in young and older adults.
© Copyright 2026, Nutrition Evidence
NED wishes to thank the following organisations for their support:
We use cookies to improve your experience and analyze site traffic with Google Analytics. By continuing to use our site, you agree to our use of cookies. Learn more.