An Example of a Biological Value of a Protein

November 19, 2025 •

5 min read

According to research, the biological value (BV) is a measure of the proportion of absorbed protein from a food that is incorporated into the proteins of the body. A highly effective and prime example of a protein with high biological value is egg protein, which often serves as a benchmark for comparison.

Quick Summary

The biological value (BV) of a protein measures how efficiently the body uses absorbed protein for tissue synthesis. Egg protein is a classic example of a high BV protein, frequently scoring at or near the top due to its complete essential amino acid profile that closely matches human requirements.

Key Points

Egg protein is a primary example: With a historical BV of 100, whole egg protein is considered the benchmark for measuring protein quality because it contains an ideal balance of essential amino acids.
Biological value measures retention: The BV indicates the proportion of absorbed protein that the body successfully retains and utilizes for tissue synthesis.
Essential amino acids are key: High BV proteins contain all nine essential amino acids in the right proportions required by the human body for optimal protein synthesis.
Whey protein often scores higher: Some protein supplements, such as whey protein, can have a relative BV over 100, reflecting their high concentration and rapid bioavailability.
Complementation boosts BV: Plant-based proteins can achieve a high biological value when combined in a meal, such as pairing rice with beans, to create a complete amino acid profile.
Processing can affect BV: The preparation of food, including cooking and isolation techniques, can influence a protein's digestibility and, consequently, its biological value.
High BV supports muscle and repair: High biological value proteins are particularly important for athletes and those needing tissue repair, as they are efficiently used for muscle growth and maintenance.

What is a Biological Value of a Protein?

The biological value (BV) is a metric used in nutrition to assess the quality of a protein source. It specifically measures the percentage of absorbed protein that the body retains for use in forming new protein, such as for muscle repair and growth, rather than being excreted. This is different from simply knowing the total protein content of a food. For a protein to have a high BV, it must contain all nine essential amino acids (EAAs) in the right proportions that are needed for human protein synthesis. The body cannot produce these EAAs on its own, so they must be obtained from the diet.

A protein with a low BV might be deficient in one or more of these essential amino acids, which creates a 'limiting factor' that hinders the body's ability to create new protein structures, no matter how much is consumed. Therefore, understanding the BV helps in selecting protein sources that are most efficiently used by the body.

Example: Egg Protein as the Benchmark

Whole egg protein is widely cited as a prime example of a food with a high biological value, historically scoring a BV of 100 on the relative scale. This value serves as a reference point for evaluating other protein sources. The reason for the egg's superior rating lies in its nearly perfect balance of all nine essential amino acids, making it an ideal source for human metabolic needs.

Complete Amino Acid Profile: Egg protein provides all the EAAs in a ratio that is highly compatible with the human body's requirements.
High Digestibility: The protein in eggs is also highly digestible, meaning the body can easily break it down and absorb the constituent amino acids.
Versatility: Eggs are a versatile food source, and cooking them actually improves protein bioavailability. Studies have shown that the body absorbs significantly more protein from cooked eggs compared to raw eggs.

Other examples of high BV proteins

While egg is the standard, several other protein sources are also known for their high biological value:

Whey Protein: A milk-derived protein often found in supplements, whey protein has a very high biological value, with some forms (e.g., whey protein concentrate) even exceeding the egg's traditional reference value, scoring around 104. It is known for its rapid absorption rate, making it a popular choice for post-workout recovery.
Casein Protein: Also from milk, casein has a lower BV than whey but is digested much more slowly. This allows for a sustained release of amino acids into the bloodstream, which is beneficial for muscle maintenance over longer periods, such as overnight.
Meat, Poultry, and Fish: These animal-based proteins generally offer a complete amino acid profile and high BV. Examples include beef with a BV of 74 and fish with a BV of 76.
Soy Protein: This is one of the few plant-based proteins considered complete, containing all essential amino acids in good proportion. It boasts a BV of 74.

How Biological Value Is Measured

The biological value is a scientific measure determined under strict conditions, often using a nitrogen balance study. The process typically involves feeding a test subject a specific protein source and then measuring the amount of nitrogen excreted versus the amount absorbed. The formula for calculating BV is:

$BV = (Nitrogen Retained / Nitrogen Absorbed) * 100$

Nitrogen Retained: The difference between the nitrogen consumed and the nitrogen excreted in urine and feces.
Nitrogen Absorbed: The nitrogen consumed minus the nitrogen excreted in the feces.

This calculation provides a percentage that reflects the efficiency of protein utilization. While a BV of 100% signifies maximum theoretical utilization of absorbed protein, values can sometimes exceed 100 on the relative scale (e.g., whey protein), depending on the reference used.

Factors Influencing a Protein's Biological Value

Several factors can influence a protein's BV, highlighting that its quality is not solely determined by its source.

Amino Acid Composition: The balance and proportion of essential amino acids are the most critical factor. A complete protein has a higher BV.
Food Preparation: Cooking can either increase or decrease BV. For instance, cooking an egg denatures proteins, improving digestibility and thus BV. However, intense heat can also damage or destroy amino acids, potentially reducing BV.
Combination of Foods: Consuming different protein sources in the same meal, a process known as protein complementation, can significantly boost the overall BV of the meal. For example, combining rice (low in lysine) with beans (low in methionine) results in a complete protein meal with a higher BV than either food alone.
Individual Metabolism: An individual's age, health, and current metabolic state can all affect how efficiently they utilize dietary protein.

Comparison Table: Protein Sources by Biological Value (Relative)


Protein Source	Typical Biological Value	Notes
Whey Protein	104	Very high BV, fast-digesting, ideal for post-workout.
Whole Egg	100	The classic gold standard; contains a perfect balance of EAAs.
Cow's Milk	91	Contains both whey (fast) and casein (slow) proteins.
Soy Protein	74	One of the highest-rated complete plant proteins.
Beef	74	Complete animal protein source.
Casein Protein	77	Milk protein that is slowly digested, providing a steady amino acid release.
Fish	76	Complete animal protein source.
Pea Protein	65	Plant-based protein, higher BV when combined with other sources like rice.

The Importance of High Biological Value Proteins

Incorporating high BV proteins into your diet offers numerous benefits. They are particularly important for muscle protein synthesis, tissue repair, and the production of hormones and enzymes. For athletes, or those recovering from injury, consuming high BV protein can optimize recovery and support muscle growth. A diet with a proper balance of high BV proteins also helps to maintain a positive nitrogen balance, which is crucial for overall health.

While animal sources are renowned for their high BV, a well-planned vegetarian or vegan diet can achieve similar results through protein complementation. This strategy involves combining two or more plant-based protein sources, which are individually incomplete, to create a complete amino acid profile in a single meal. An example is pairing legumes with grains, such as beans and rice. This demonstrates that a high-quality protein intake is accessible regardless of dietary preferences.

Conclusion

The biological value of a protein provides a clear indication of how effectively the body can utilize it for essential functions like tissue repair and muscle growth. Egg protein serves as a classic and well-recognized example of a high BV protein due to its complete essential amino acid profile and high digestibility. However, many other sources, both animal-based (whey, casein, meat) and plant-based (soy, combined legumes and grains), also offer high biological value. By understanding these principles, individuals can make informed dietary choices to ensure they receive the highest quality protein for their specific health and fitness goals.

Frequently Asked Questions

High biological value is generally considered to be a score of 70 or higher on a scale where whole egg protein is the reference standard at 100. Foods with a high BV, like eggs and whey, are rich in essential amino acids and are efficiently utilized by the body.

No, not all proteins are equally beneficial. A protein's nutritional value depends on its amino acid composition and digestibility. Proteins with a high biological value are more efficiently used by the body for growth and repair compared to those with a low BV.

Yes, it is possible to achieve a high biological value from plant-based proteins through a practice called protein complementation. By combining two or more plant sources, such as rice and beans, the amino acid deficiencies of each are offset, creating a complete protein profile comparable to animal proteins.

Processing can significantly impact biological value. While methods like cooking can improve the digestibility of some proteins (like eggs), other forms of processing, especially involving intense heat, can damage or denature amino acids, potentially reducing the protein's overall quality.

Whole egg protein is used as a benchmark because it has a near-perfect amino acid profile that closely matches the requirements of the human body for optimal protein synthesis. This makes it an ideal reference standard for comparison.

No, biological value is one of several measures of protein quality. Other metrics include Net Protein Utilization (NPU), Protein Efficiency Ratio (PER), and the more recent Digestible Indispensable Amino Acid Score (DIAAS). Each method assesses protein quality from a slightly different perspective.

Whey protein typically has a higher BV than casein. However, whey is known as a "fast" protein due to its rapid digestion and absorption, while casein is a "slow" protein with a sustained release of amino acids, offering different benefits for muscle synthesis over time.