Protein quality: What is it, what affects it, and how much does it matter?
Stronger By ScienceKey Moments
Protein quality matters less than previously thought for muscle building. Focus on total intake and variety.
Key Insights
Cooking increases egg protein digestibility significantly, but this doesn't translate to better muscle protein synthesis than raw eggs.
The chain of assumptions (quality -> amino acid response -> MPS -> hypertrophy) often breaks down; small differences in protein quality have minimal impact on long-term muscle growth.
Animal-based proteins generally have higher leucine and essential amino acid content than plant-based proteins.
Variety in protein sources is key, especially for vegans, to ensure adequate intake of all essential amino acids.
Total daily protein intake within recommended ranges (1.6-2.2 g/kg body weight for hypertrophy) is more critical than micromanaging specific protein sources.
In specific medical situations requiring protein restriction, prioritizing high-quality proteins may be more beneficial.
THE MYTH OF RAW VS. COOKED EGGS AND PROTEIN DIGESTIBILITY
While cooking significantly enhances the digestibility of egg protein, moving from 51% to 91% true ileal digestibility, this enhanced digestibility does not translate into superior muscle protein synthesis (MPS) rates compared to raw eggs. A study comparing raw and cooked egg consumption after resistance training found virtually identical MPS rates between the two groups over a five-hour period. Despite raw eggs showing a less robust immediate amino acid response in the blood, the long-term muscle-building potential appeared the same, challenging assumptions about immediate nutrient uptake dictating muscle growth.
DECONSTRUCTING THE PROTEIN ASSUMPTION CHAIN
A common sequence of assumptions links protein quality (amino acid profile and digestibility) to blood amino acid response, then to acute muscle protein synthesis, and finally to long-term hypertrophy. However, research suggests this chain is not as linear or directly correlated as often believed. Small differences in protein quality scores or acute MPS responses do not reliably predict long-term muscle growth. The impact of resistance training itself is also a major factor, often overshadowing minor differences in protein sources.
ANIMAL VS. PLANT-BASED PROTEINS: QUALITY AND COMPOSITION
Animal-based proteins generally offer higher leucine and essential amino acid content per gram compared to most plant-based proteins. Key limiting amino acids in plant proteins often include lysine and methionine. While there's variability among animal proteins (e.g., cod being lower in leucine), and some plant proteins like soy and mycoprotein are high-quality, the general trend favors animal sources for amino acid profiles relevant to muscle building. However, this quality difference doesn't automatically translate to vastly superior hypertrophy outcomes.
HYPERTROPHY OUTCOMES: WHERE QUALITY'S IMPORTANCE FADES
While higher-quality proteins might show advantages in acute muscle protein synthesis, especially without resistance training, these differences tend to dissipate when considering long-term hypertrophy and strength gains. Meta-analyses and studies comparing vegan and omnivorous diets, even those with plant-based proteins like soy or mycoprotein, show similar improvements in muscle mass and strength when total protein intake is sufficient. This suggests that the body can effectively utilize a variety of protein sources for muscle adaptation.
PRACTICAL STRATEGIES FOR OPTIMAL PROTEIN INTAKE
The focus should be on meeting total daily protein targets (1.6-2.2 g/kg body weight for hypertrophy) and ensuring variety rather than obsessing over minute differences in protein quality scores. For vegans, complementary protein sources (mixing foods that are low in different essential amino acids) are effective. For omnivores, a significant portion of protein often comes from plant sources, and this is generally not detrimental. Basic preparation methods like cooking are important, but extreme meticulousness in protein source selection is likely unnecessary for most.
WHEN PROTEIN QUALITY MAY MATTER MORE
The primary assumption in this discussion is that the individual is resistance training and aiming to maximize muscle hypertrophy. However, in specific medical situations where protein intake must be restricted (under professional guidance), prioritizing high-quality protein sources becomes more relevant. In such cases, the goal is to maximize the 'bang for your buck' – achieving the best possible muscle-building response from a limited protein intake, making the efficiency and completeness of the amino acid profile more critical.
Mentioned in This Episode
●Supplements
●Products
●Software & Apps
●Studies Cited
●Concepts
●People Referenced
Protein Quality & Intake for Muscle Growth: Key Takeaways
Practical takeaways from this episode
Do This
Avoid This
True Ileal Digestibility of Egg Protein
Data extracted from this episode
| Preparation | Digestibility (%) |
|---|---|
| Raw | 51 |
| Cooked | 91 |
Protein Source Contribution in Omnivorous Diets (Worldwide Average)
Data extracted from this episode
| Source Type | Contribution (%) |
|---|---|
| Animal-based | 42 |
| Plant-based | 58 |
Common Questions
While raw eggs may have a similar amino acid profile, studies show cooked eggs have significantly higher digestibility. However, a key study found no significant difference in muscle protein synthesis rates between raw and cooked eggs after resistance training, suggesting cooking has minimal impact on muscle growth.
Topics
Mentioned in this video
A protein supplement for individuals with difficulty chewing or digesting food, described as viscous and low in protein.
Used as an analogy for how initial research findings in muscle growth can be misleading or oversimplified.
Mentioned humorously in relation to cod consumption.
The recommended daily allowance for protein, which the speaker notes the fitness industry has 'aggressively' increased beyond.
A metric used to quantify protein quality, assessing how well proteins are absorbed and retained.
Source of a graphic categorizing plant-based protein sources.
A seed mentioned as a source of protein that is lower in lysine.
An ingredient used in the speaker's homemade mass gainer shake.
An older metric used to quantify protein quality based on animal studies.
An animal protein source noted as being particularly low in leucine and methionine.
A seed mentioned as a source of protein that is lower in lysine.
Consumed in large quantities in a homemade shake; discussed in terms of safety and impact on muscle protein synthesis.
The sport the speaker started getting into, influencing his weight gain goals.
A seed mentioned as a source of protein that is lower in lysine.
A metric for protein quality that considers both amino acid content and digestibility.
The primary outcome measured in the study comparing raw and cooked eggs, and a key factor in muscle hypertrophy.
Lead author of a study comparing diets with soy protein for muscle hypertrophy and strength.
A grain mentioned as a source of protein that is lower in certain essential amino acids like methionine.
Lead author of a 1998 study on egg protein digestibility.
The process of muscle growth, which the video aims to optimize through protein intake and training.
An ingredient used in the speaker's homemade mass gainer shake, contributing to taste and palatability.
An essential amino acid that can be limiting in some plant-based protein sources.
A grain mentioned as a source of protein that is lower in certain essential amino acids like methionine.
An ingredient used in the speaker's homemade mass gainer shake, contributing to taste and palatability.
A metric used to quantify protein quality, measuring the percentage of absorbed protein retained by the body.
Part of the control group's meal in the raw vs. cooked egg study.
Used as a comparison for protein quality and leucine content.
A nut mentioned as a source of protein that is lower in lysine.
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