How can we improve protein quality for better health and muscle gain?

January 8, 2026 •

3 min read

Not all protein is created equal; animal-based sources generally contain all nine essential amino acids (EAAs), while many plant-based proteins do not. Understanding this key difference is the first step in learning how can we improve protein quality in our daily diets for better overall health and specific goals like muscle gain.

Quick Summary

This guide explains the key factors that determine protein quality, focusing on amino acid profiles and digestibility. It provides practical strategies for combining complementary protein sources and optimizing digestion for maximum bodily utilization.

Key Points

Combine Sources: For plant-based diets, combine different protein sources like grains and legumes to ensure all essential amino acids are consumed.
Boost Digestibility: Eat fermented foods, chew thoroughly, and use optimal cooking methods to enhance the body's absorption of amino acids.
Choose High-Quality: Prioritize protein sources with a complete amino acid profile, like animal proteins, soy, or quinoa, for optimal muscle protein synthesis.
Diversify Your Diet: Eating a wide variety of protein sources provides a broader spectrum of nutrients and health benefits beyond just protein.
Focus on Leucine: For building muscle, prioritize protein sources high in the essential amino acid leucine, such as whey or soy.
Consider the Protein Package: Look beyond just protein grams; consider the associated healthy fats, fiber, and micronutrients that come with each source.

Understanding Protein Quality: Beyond the Numbers

Protein is a crucial macronutrient, but focusing solely on the total number of grams can be misleading. A protein's true value, its quality, depends on two primary factors: its amino acid profile and its digestibility. A high-quality protein provides all nine essential amino acids (EAAs) in sufficient amounts, which the body cannot produce on its own. Digestibility refers to how well the body can absorb the ingested protein and its amino acids. For muscle growth and repair, the EAA leucine is particularly important as it signals muscle protein synthesis.

The Role of Amino Acids and Digestibility

Our bodies constantly break down and rebuild proteins using amino acids as building blocks. Protein quality is determined by the completeness of its amino acid profile and how effectively these amino acids are absorbed (digestibility).

Methods for Measuring Protein Quality

Protein quality is evaluated using scoring methods. The older method, PDCAAS, is being replaced by the DIAAS, which is recommended by the FAO. DIAAS provides a more accurate score by assessing the digestibility of individual amino acids in the ileum and is not capped at 1.0, unlike PDCAAS.

Comparison of Protein Quality Measures


Feature	PDCAAS	DIAAS
Measurement	Compares fecal nitrogen digestibility against EAA requirements for children aged 2-5.	Assesses ileal digestibility of individual EAAs against age-specific requirements.
Cap	Truncated, capped at 1.00.	Not truncated, can be >1.00.
Accuracy	Less accurate for higher-quality proteins, overestimates lower-quality ones.	More precise and accurate, especially for higher-quality proteins.
Reference Pattern	Uses reference pattern for children 2-5 years old.	Uses age-specific amino acid requirements.
Use Case	Historically used for regulatory purposes in the US.	Recommended by FAO for modern food labelling and research.

Practical Strategies for Improving Protein Quality

To improve protein quality, consider food pairings, meal timing, and focusing on digestibility. Combining plant protein sources throughout the day can ensure intake of all essential amino acids for vegetarians and vegans. Key pairings include legumes with grains, nuts/seeds with legumes, nuts/seeds with whole grains, and vegetables with nuts/seeds. Food preparation also impacts digestibility. Cooking can make proteins more digestible, while overcooking might reduce it. Thorough chewing helps. Fermented foods like tempeh can also improve digestibility by breaking down proteins. Additionally, gut health is important for protein digestion and absorption.

The “Protein Package”: Animal vs. Plant Sources

Consider the 'protein package,' which includes other nutrients. Animal proteins are typically complete and highly digestible. Plant-based diets offer benefits like fiber and antioxidants. A diverse range of protein sources is healthiest. Some plant sources like soy, quinoa, and hemp seeds are complete proteins.

Summary

Improving protein quality involves understanding amino acid composition and digestibility. Combining diverse protein sources, optimizing cooking methods, and supporting digestive health are key strategies. A varied diet with both complete and complementary proteins from animal and plant sources is most effective for health and muscle synthesis.

For more detailed information on protein science, consider reading reviews on the evolution of amino acid scoring, such as {Link: frontiersin.org https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2024.1437853/full}.

Conclusion

To improve protein quality, focus on amino acid profile and digestibility. Combine diverse sources, especially plant-based ones, to ensure all essential amino acids are consumed. Enhance digestion through proper cooking, chewing, and fermented foods. Prioritizing a variety of high-quality protein sources supports better health and muscle synthesis.

Frequently Asked Questions

Protein quality is primarily determined by two factors: its amino acid profile, specifically its content of the nine essential amino acids (EAAs), and its digestibility, which is how well the body can absorb and utilize those amino acids.

No, you do not need to combine complementary proteins in the same meal. The body maintains a pool of amino acids from various foods throughout the day, so consuming different sources, like grains and legumes, across meals is sufficient.

Animal proteins are typically 'complete,' meaning they contain all nine essential amino acids. Many plant proteins are 'incomplete' and lack sufficient quantities of one or more EAAs, though some, like soy and quinoa, are complete.

Yes, cooking can improve protein quality by denaturing protein structures and reducing anti-nutritional factors, making them more accessible to digestive enzymes. Low-temperature methods like sous vide can be particularly effective.

A protein's digestibility directly affects its quality, as the body can only use the amino acids that are successfully absorbed. Improving digestibility, such as through cooking or fermented foods, increases the bioavailability of protein.

PDCAAS is an older scoring method that assesses protein digestibility in feces, is capped at 1.0, and based on children's EAA needs. DIAAS is a more modern, accurate method that measures individual amino acid digestibility in the ileum and is not capped, allowing for better comparison of high-quality proteins.

While all essential amino acids are necessary, leucine, one of the branched-chain amino acids (BCAAs), is particularly important for stimulating muscle protein synthesis and promoting muscle growth.