How to Improve the Quality of Protein in Your Diet

December 20, 2025 •

3 min read

According to the Food and Agriculture Organization of the United Nations, a new metric called the Digestible Indispensable Amino Acid Score (DIAAS) is now considered the most accurate way to measure protein quality. This metric highlights that not all protein sources are created equal, and some are more efficiently absorbed and utilized by the body than others.

Quick Summary

This article explores the crucial role of protein quality in human nutrition, explaining concepts like essential amino acids and bioavailability. It offers actionable strategies for selecting and preparing protein sources, covering both animal and plant-based options to maximize your body's utilization of this vital macronutrient.

Key Points

Amino Acid Completeness: To get the most from your diet, prioritize sources like meat, eggs, and soy which offer all nine essential amino acids, or strategically combine incomplete plant proteins.
Enhance Digestibility: Utilize cooking methods like moist heat (stewing) or fermentation to break down protein structures and anti-nutritional factors, making them easier for the body to absorb.
Combine Incomplete Proteins: If you're on a plant-based diet, combine different sources throughout the day, such as rice and beans or nuts and grains, to ensure a complete essential amino acid profile.
Manage Your Eating Schedule: Spreading protein consumption across multiple meals, rather than consuming it all at once, can lead to more efficient absorption and utilization.
Boost Digestive Function: Supporting overall digestive health through thorough chewing, stress reduction, and incorporating probiotics can improve your body's ability to break down and absorb protein.
Prioritize Nutrient-Dense Foods: Beyond protein, focus on a varied diet of whole foods, as processing can diminish nutrient availability and add unhealthy additives.
Cooking Matters: Be mindful of cooking techniques; while some heat helps, excessive high-temperature cooking can damage protein and reduce its nutritional value.

Understanding Protein Quality: More Than Just Grams

Protein is a vital macronutrient that serves as the building block for tissues, enzymes, and hormones in the body. However, focusing solely on the quantity of protein can be misleading. Protein quality is determined by two main factors: its amino acid profile and its digestibility. Amino acids are the smaller compounds that make up proteins, and there are nine 'essential amino acids' that our bodies cannot produce, meaning we must obtain them from our diet. A 'complete protein' source contains all nine essential amino acids in sufficient amounts, while 'incomplete proteins' are lacking in one or more. Furthermore, the bioavailability of a protein—how easily the body can absorb and utilize it—is also a critical component of its quality.

Maximizing Bioavailability and Digestibility

Improving the quality of protein is not just about choosing the right foods but also about how you prepare and combine them. By focusing on these techniques, you can ensure your body gets the most out of every protein-rich meal.

Strategic Combinations for Plant-Based Diets

For those on a plant-based diet, combining different protein sources is an effective way to create a complete amino acid profile. A common myth is that complementary proteins must be eaten in the same meal, but this is not true; your body can draw from a reserve of amino acids throughout the day.

Pairing grains and legumes: A classic example is rice and beans, where the amino acids lacking in one are supplied by the other. This combination creates a complete protein that provides all the essential amino acids.
Nuts/Seeds with Grains: Spreading peanut butter on whole-wheat bread or sprinkling sesame seeds on whole grains are simple ways to complement protein profiles.
Varying your vegetables: Some vegetables also contribute to the amino acid pool. For example, broccoli with whole-grain pasta provides a more complete protein meal.

Smart Cooking and Preparation Methods

The way food is prepared can significantly impact protein digestibility. Excessive heat, for instance, can cause protein cross-linking, which reduces bioavailability. In contrast, some preparation methods can improve it.

Moist heat cooking: Methods like stewing can improve the digestibility of proteins.
Fermentation: Fermenting legumes and other plant proteins can break down anti-nutritional factors that inhibit digestion, thereby increasing the protein's bioavailability.
Avoiding overcooking: While some heat is beneficial, overcooking or high-temperature frying can create protein aggregates that are resistant to digestive enzymes.

Table: High vs. Low Bioavailability Protein Sources


Protein Source	Typical Bioavailability	Amino Acid Profile	Best Practices
Whey Protein Isolate	Very High (up to 159)	Complete and easily absorbed	Ideal post-workout for fast muscle synthesis.
Eggs	High (100 is reference score)	Complete, highly digestible.	Consume whole egg for complete nutrient profile, cook thoroughly.
Red Meat	Moderate	Complete, good source of iron.	Best in lean cuts, moderate consumption, avoid overcooking.
Soy	High	Complete plant protein, easily digestible.	Incorporate tofu or tempeh; check processing for best quality.
Legumes (Beans)	Moderate to low	Incomplete (often low in methionine).	Combine with grains like rice to form a complete protein.
Whole Grains	Moderate to low	Incomplete (often low in lysine).	Combine with legumes or nuts for a complete profile.

Optimizing Your Digestive Health

Effective digestion is a prerequisite for maximum protein absorption. If your digestive system is not functioning optimally, even high-quality protein sources will not be fully utilized. Focusing on these habits can help.

Eat regularly: Spreading protein intake throughout the day, rather than in one large meal, can improve absorption.
Thorough chewing: Breaking down food mechanically in the mouth eases the load on the digestive system.
Manage stress: High-stress levels can impair digestive function.
Consider probiotics: Some probiotics can improve the absorption of certain proteins.

Conclusion

Improving the quality of protein intake is a multifaceted process that goes beyond simply counting grams. It requires a mindful approach to food choices, preparation, and overall digestive health. By understanding the principles of amino acid profiles, bioavailability, and complementary proteins, you can make smarter dietary decisions that significantly enhance your body's ability to utilize this essential nutrient. Incorporating a variety of both animal and plant-based proteins, using smart cooking techniques, and supporting a healthy digestive system are all key to unlocking the full nutritional potential of your diet. Remember, the goal is not just to consume protein, but to help your body absorb and use it most efficiently for optimal health.

For a deeper dive into the technical details of protein quality assessment, explore the standards and research by the Food and Agriculture Organization (FAO) of the United Nations.

Frequently Asked Questions

Protein quality is a measure of how efficiently a protein source provides the essential amino acids needed by the body, taking into account both the protein's amino acid composition and its digestibility.

Complete proteins are food sources that contain all nine essential amino acids. Animal products like meat, fish, eggs, and dairy are complete proteins, as are a few plant-based options like soy and quinoa.

No. Your body can effectively combine amino acids from various foods eaten throughout the day to create complete proteins. This process is more flexible than the old belief that pairing must occur in a single meal.

Cooking can either improve or decrease protein quality. Moist heat cooking often increases digestibility, while excessive or high-temperature cooking can damage amino acids and form protein aggregates that are harder to digest.

Bioavailability is a measure of how easily and effectively the body can absorb and use a nutrient. A highly bioavailable protein is efficiently utilized, while a protein with low bioavailability may pass through the body with less absorption.

Animal proteins generally have higher digestibility and contain all essential amino acids. However, a well-planned plant-based diet that combines different protein sources can provide a complete amino acid profile, and may offer additional health benefits.

Even the highest-quality protein is useless without proper digestion. Factors like thorough chewing, managing stress, and maintaining a healthy gut all contribute to a digestive process that maximizes amino acid absorption from your food.