Unlocking the Protein Puzzle: Animal-Based vs. Plant-Based Protein Bioavailability

Animal-Based vs. Plant-Based Protein

Animal-Based vs. Plant-Based Protein Bioavailability

Consuming equal ounce-equivalent portions of animal-based and plant-based protein foods, as recommended by the Dietary Guidelines for Americans, leads to varying levels of essential amino acid bioavailability in both young and older adults.

In the realm of nutrition, the age-old debate over animal-based versus plant-based protein sources has taken a new turn. A recent study conducted by scientists at Purdue University challenges the prevailing notion that protein from animal-based and plant-based sources are nutritionally equivalent. The study delves into the intricate world of essential amino acids (EAAs) and their bioavailability, shedding light on how our bodies process and utilize these building blocks of muscle and whole-body health.

Unraveling the Protein Quality

The quality of protein isn’t solely determined by its quantity; the composition of essential amino acids plays a vital role. EAAs are the foundation of muscle and whole-body protein building. As per the Dietary Guidelines for Americans (DGAs), ounce-equivalent portions of protein foods are considered equivalent. But are they truly nutritionally alike? Dr. Wayne Campbell, the primary investigator of the study, raises a pertinent question: “The basis for the DGAs stating that these protein foods are ‘equivalent’ and have ‘similar nutritional content’ is unclear.”

The Study Design and Execution

To address this question, researchers conducted two cross-over randomized controlled trials involving both young and older adults. Participants consumed standardized meals containing two oz-eq of either animal-based protein foods (lean pork loin, scrambled whole eggs) or plant-based protein foods (black beans, raw sliced almonds). Blood samples were taken at various intervals to assess EAA bioavailability, blood sugar, and insulin levels.

EAA Bioavailability: Animal vs. Plant

The findings were clear. Meals with two oz-eq of animal-based protein foods resulted in higher EAA levels in the bloodstream compared to plant-based protein meals, for both young and older adults. Dr. Gavin Connolly, a key researcher, explains, “This is an important consideration for muscle and whole-body health and physical function across the life course.” In essence, animal-based proteins provide a more effective source of EAAs, critical for building body protein and muscle.

Unveiling Additional Insights

The study also uncovered specific nuances:

  • Lean pork outperformed eggs in terms of EAA bioavailability for both age groups.
  • No significant difference in EAA bioavailability was observed between black beans and almonds.
  • EAA bioavailability did not differ significantly between young and older adults.

Towards Informed Dietary Recommendations

These results hold significant implications for public health nutrition guidance and the future revision of DGAs. The study authors suggest that the protein sources’ varying EAA bioavailability challenges the notion of nutritional equivalence. Dr. Campbell emphasizes, “Guidance on the importance of nutrient-dense animal-based protein foods which are high-quality protein sources is important information to incorporate when providing dietary recommendations.”

The Quest for Comprehensive Understanding

While this study sheds light on the intricate world of protein bioavailability, it also acknowledges its limitations. Further research is needed to explore the long-term impact of animal-based versus plant-based protein foods on muscle and whole-body health. As the quest for optimal nutrition continues, this study stands as a milestone in our journey toward understanding how the protein puzzle fits into the broader canvas of a balanced diet.

References: “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” by Gavin Connolly, Joshua L. Hudson, Robert E. Bergia, Eric M. Davis, Austin S. Hartman, Wenbin Zhu, Chad C. Carroll and Wayne W. Campbell, 25 June 2023, Nutrients. DOI: 10.3390/nu15132870 “Quality of meal protein determines anabolic response in older adults” by Il-Young Kim, Yun-A. Shin, Scott E. Schutzler, Gohar Azhar, Robert R. Wolfe and Arny A. Ferrando, 6 October 2017, Clinical Nutrition. DOI: 10.1016/j.clnu.2017.09.025 “Metabolic Evaluation of the Dietary Guidelines’ Ounce Equivalents of Protein Food Sources in Young Adults: A Randomized Controlled Trial” by Sanghee Park, David D Church, Scott E Schutzler, Gohar Azhar, Il-Young Kim, Arny A Ferrando and Robert R Wolfe, 9 March 2021, The Journal of Nutrition. DOI: 10.1093/jn/nxaa401 Essential Amino Acids and Protein Synthesis: Insights into Maximizing the Muscle and Whole-Body Response to Feeding” by David D. Church, Katie R. Hirsch, Sanghee Park, Il-Young Kim, Jess A. Gwin, Stefan M. Pasiakos, Robert R. Wolfe and Arny A. Ferrando, 2 December 2020, Nutrients. DOI: 10.3390/nu12123717 This research was funded by the National Pork Board and the American Egg Board—Egg Nutrition Center.