Plant vs Animal Protein
Exploring the anabolic responses of different protein sources and their implications for muscle mass.
This study, authored by Stephan van Vliet, Nicholas A. Burd, and Luc J.C. van Loon, investigates the differences in skeletal muscle protein synthesis (MPS) responses to plant-based versus animal-based protein consumption.
PMID: 26224750
The research highlights the growing interest in plant proteins due to their potential health benefits and environmental sustainability. Yet, it raises concerns about their effectiveness in promoting muscle mass compared to animal proteins.
Key Points
Muscle Protein Synthesis (MPS): MPS is crucial for maintaining or increasing skeletal muscle mass. It is primarily stimulated by dietary protein intake and physical activity. The response to protein ingestion lasts about 4-5 hours, necessitating regular daily protein consumption.
Plant vs. Animal Proteins: Current evidence suggests that plant proteins, particularly soy and wheat, elicit a lower MPS response than animal proteins like whey, milk, and beef. This difference may be attributed to:
Digestibility: Plant proteins generally have lower digestibility rates (45%-80%) compared to animal proteins (>90%).
Amino Acid Composition: Plant proteins often lack specific essential amino acids (EAAs), particularly leucine, vital for stimulating MPS.
Urea Synthesis: Amino acids from plant sources are more likely to be converted into urea rather than being utilised for muscle synthesis.
Protein Quality Assessment: The study critiques existing measures of protein quality (e.g., PDCAAS) for not accurately reflecting the anabolic potential of different protein sources. For instance, soy has a high PDCAAS score (0.91), comparable to beef (0.92), yet studies show beef stimulates MPS more effectively.
Strategies to Enhance Plant Protein Efficacy:
Fortifying plant proteins with methionine, lysine, and leucine.
Selective breeding of plants to improve amino acid profiles.
Increasing the quantity of plant protein consumed.
Combining multiple plant protein sources to achieve a balanced amino acid profile.
Related
Key Takeaways
Need for Further Research: Studies assessing the postprandial MPS response to a broader range of plant proteins beyond soy are lacking. Future research should explore various plant sources and their potential roles in nutritional interventions targeting muscle mass maintenance or gain.
Practical Implications: For individuals relying on plant-based diets—such as vegetarians or vegans—it's essential to consider the quality and combination of protein sources consumed to ensure adequate muscle protein synthesis.
Sustainability Considerations: While plant-based diets are associated with lower environmental impact than animal-based diets, their effectiveness in supporting muscle health needs careful evaluation.
In conclusion, while there is a growing trend towards plant-based diets for health and sustainability reasons, this study underscores the necessity of understanding their limitations regarding muscle anabolism compared to traditional animal-based proteins.
Limitations and Biases
Limited Scope of Plant Proteins Studied: The primary focus is on soy and wheat proteins, with little exploration of other plant protein sources. This narrow scope may not represent the full spectrum of plant-based proteins available, limiting the generalizability of the findings.
Digestibility Variability: The study acknowledges that digestibility rates can vary significantly among different plant proteins due to factors like processing methods and the presence of anti-nutritional factors. However, it lacks comprehensive data on the digestion and absorption kinetics of a wider range of plant proteins, which could provide a more balanced view.
Protein Quality Assessment Methods: The reliance on PDCAAS and similar measures to evaluate protein quality is critiqued for not accurately reflecting the anabolic potential of proteins. While these methods provide useful information, they may misrepresent the effectiveness of certain plant proteins compared to animal proteins.
Potential Bias in Research Focus: The authors note a disproportionate amount of research on animal proteins compared to plant proteins. This bias in existing literature may influence the conclusions drawn in the study, as it primarily contrasts well-studied animal proteins against less-researched plant sources.
A generalisation of Findings: The study's conclusions regarding the lower anabolic response of plant proteins may not apply universally across all populations (e.g., athletes vs. sedentary individuals) or dietary contexts (e.g., mixed diets vs. strict vegetarian diets).
Lack of Longitudinal Data: The study primarily examines acute responses to protein ingestion without considering long-term effects on muscle mass and function, which are crucial for understanding dietary impacts over time.
Reference
van Vliet S, Burd NA, van Loon LJ. The Skeletal Muscle Anabolic Response to Plant- versus Animal-Based Protein Consumption. J Nutr. 2015 Sep;145(9):1981-91. doi: 10.3945/jn.114.204305. Epub 2015 Jul 29. PMID: 26224750.