Biological Value of Protein: What BV Means and Why It Matters

Biological value, commonly abbreviated as BV, is a traditional method used to evaluate the quality of dietary protein.

The concept of biological value focuses on how efficiently the body can use absorbed protein for its own protein needs.

Although biological value was once one of the most widely discussed measures of protein quality, modern nutrition science uses several different methods to evaluate proteins.

Understanding biological value can nevertheless help explain why different protein sources are not nutritionally identical and why amino acid composition and protein digestibility are important.

What Is Biological Value?

Biological value is a measure of how efficiently absorbed dietary protein is retained and used by the body.

In simplified terms, biological value attempts to answer the question:

How much of the absorbed protein is retained by the body for protein synthesis and other biological functions?

A higher biological value indicates that a greater proportion of the absorbed nitrogen from protein is retained rather than excreted.

Biological value is therefore closely related to nitrogen balance and protein metabolism.

However, BV is not a direct measurement of how much muscle you will gain from eating a particular protein source.

How Is Biological Value Calculated?

Biological value is traditionally calculated by comparing nitrogen intake with nitrogen retention.

A simplified representation is:

BV = Nitrogen retained ÷ Nitrogen absorbed × 100

The result is expressed as a percentage or score.

A protein with a BV of 100 would theoretically mean that 100% of the absorbed nitrogen was retained.

In practice, biological value measurements depend on experimental conditions and the specific protein source being studied.

Why Is Nitrogen Important?

Protein is the primary source of dietary nitrogen.

When your body digests protein, it breaks it down into amino acids.

These amino acids can be used to build new proteins and other compounds.

When amino acids are broken down, their nitrogen-containing components are processed and eventually excreted.

By studying nitrogen intake, absorption, retention, and excretion, researchers can estimate how efficiently the body is using dietary protein.

Read more about this topic in our guide Nitrogen Balance Explained.

What Does a High Biological Value Mean?

A high biological value generally indicates that the amino acid composition of a protein is well suited to the body's needs and that a high proportion of absorbed nitrogen is retained.

Proteins with high biological value tend to contain sufficient amounts of essential amino acids.

Examples of protein sources traditionally associated with high biological value include:

Eggs.
Milk.
Whey protein.
Fish.
Meat.

Egg protein has historically been used as a reference protein in some biological value comparisons.

However, a high BV score does not necessarily mean that a protein source is the best choice for every person or every diet.

What Does a Low Biological Value Mean?

A lower biological value generally indicates that a smaller proportion of absorbed protein nitrogen is retained by the body.

This can occur when a protein is limited in one or more essential amino acids relative to the body's requirements.

Many individual plant proteins have traditionally been assigned lower BV values than animal proteins.

However, this does not mean that plant proteins are nutritionally poor.

Different plant foods have different amino acid profiles, and combining complementary protein sources can help create a more balanced overall amino acid intake.

Explore different food combinations using our Protein Combining Score Calculator.

Biological Value and Essential Amino Acids

Essential amino acids play a major role in protein quality.

Your body cannot produce enough of these amino acids on its own, so they must be obtained through your diet.

The nine essential amino acids are:

Histidine.
Isoleucine.
Leucine.
Lysine.
Methionine.
Phenylalanine.
Threonine.
Tryptophan.
Valine.

If a protein contains insufficient amounts of one or more essential amino acids, that amino acid may limit the body's ability to use the protein for protein synthesis.

This is sometimes referred to as a limiting amino acid.

Learn more in our article Essential Amino Acids Explained.

Biological Value and Protein Digestibility

Biological value is related to protein digestibility, but the two concepts are not identical.

Protein digestibility describes how efficiently protein is digested and absorbed.

Biological value considers how efficiently the absorbed protein is retained by the body.

A protein must first be absorbed before its amino acids can be used.

Therefore, digestibility can influence how much protein becomes available to the body, while biological value focuses on how efficiently the absorbed protein is utilized.

Read more in our article Protein Digestibility Explained.

Which Protein Has the Highest Biological Value?

Egg protein has traditionally been associated with a biological value of approximately 100 and has often been used as a reference point when discussing protein quality.

Some protein sources, particularly certain whey proteins, have been reported to have biological value scores above 100 in traditional measurements.

However, these values should not be interpreted as a simple ranking of which protein is best for muscle growth or overall health.

Different protein quality scoring systems measure different aspects of protein nutrition, and results can vary depending on the experimental conditions.

Modern protein evaluation methods often place greater emphasis on the digestibility of individual essential amino acids.

Biological Value of Common Protein Sources

Traditional biological value measurements have often placed many animal-based proteins relatively high on the scale.

Examples include:

Egg protein: Traditionally used as a reference protein with a BV around 100.
Milk protein: Generally considered a high-quality protein.
Whey protein: Highly digestible and rich in essential amino acids.
Fish: Generally provides highly digestible complete protein.
Meat: Provides all nine essential amino acids.
Soy protein: A high-quality plant protein with a relatively favorable amino acid profile.
Legumes: Valuable sources of plant protein but often limited in certain essential amino acids.
Grains: Useful protein sources that can complement legumes and other plant foods.

These categories are broad, and the actual nutritional value of a food depends on the specific protein, preparation method, and overall diet.

Biological Value of Plant Protein

Plant proteins are sometimes described as having lower biological value than animal proteins.

While this can be true for individual protein sources, it does not mean that plant-based diets cannot provide adequate high-quality protein.

Plant proteins can be combined across meals and throughout the day to provide a broad range of essential amino acids.

For example, legumes are generally relatively rich in lysine but lower in methionine, while many grains provide more methionine but less lysine.

Combining a variety of plant foods can therefore help improve the overall amino acid balance of a diet.

Examples of complementary combinations include:

Beans and rice.
Lentils and bread.
Chickpeas and grains.
Peas and rice.

You can explore protein combinations with our Protein Combining Score Calculator.

Do You Need to Combine Proteins at Every Meal?

It is not generally necessary to combine complementary proteins at every meal.

The body maintains amino acid pools, and a varied diet consumed throughout the day can provide the essential amino acids needed for protein synthesis.

However, people following predominantly or exclusively plant-based diets may benefit from eating a diverse range of protein-rich foods.

Good plant protein sources include:

Tofu.
Tempeh.
Soybeans.
Lentils.
Beans.
Chickpeas.
Peas.
Quinoa.
Nuts and seeds.

The overall quality of the diet is more important than perfectly combining specific foods at every individual meal.

Biological Value and Muscle Growth

Biological value can provide useful information about protein quality, but it should not be used as a direct predictor of muscle growth.

Muscle growth depends on many factors, including:

Total daily protein intake.
Essential amino acid availability.
Leucine content.
Protein digestibility.
Resistance training.
Energy intake.
Recovery.
Sleep.

A protein source with a high biological value can provide an excellent amino acid profile, but consuming enough total protein and performing effective resistance training remain essential.

Use our Protein Need Calculator to estimate your daily protein requirements.

Biological Value vs PDCAAS

Biological value and PDCAAS are different methods of evaluating protein quality.

Biological value focuses on the proportion of absorbed nitrogen that is retained by the body.

PDCAAS, or Protein Digestibility-Corrected Amino Acid Score, considers the amino acid composition of a protein and adjusts the score based on overall protein digestibility.

PDCAAS became widely used as a standardized method for comparing protein quality.

However, it also has limitations, including the use of a truncated scoring system.

Biological Value vs DIAAS

DIAAS, or Digestible Indispensable Amino Acid Score, is a newer approach to evaluating protein quality.

Unlike traditional biological value measurements, DIAAS evaluates the digestibility of individual essential amino acids at the end of the small intestine.

This allows researchers to assess not only how much protein is digested but also how much of each essential amino acid becomes available for absorption.

For this reason, DIAAS is often considered a more detailed approach to protein quality assessment than traditional biological value measurements.

Is Biological Value Still Useful?

Biological value remains useful as a historical and educational concept.

It helps explain why protein sources differ in how effectively their amino acids can be used by the body.

However, it should not be considered the only or definitive measure of protein quality.

Modern protein nutrition considers multiple factors, including:

Essential amino acid composition.
Protein digestibility.
Digestibility of individual amino acids.
Leucine content.
Total protein intake.
Overall dietary pattern.

When evaluating protein for muscle growth or general nutrition, it is therefore better to consider the complete nutritional context rather than relying on a single score.

Frequently Asked Questions

What is biological value in protein?

Biological value is a traditional measure of protein quality that estimates how efficiently absorbed dietary protein is retained and used by the body.

Which food has the highest biological value?

Egg protein has traditionally been assigned a biological value of approximately 100 and has been used as a reference. Some whey proteins have been reported to have higher values in traditional measurements.

Is biological value the same as protein quality?

No. Biological value is one way of evaluating protein quality. Modern methods also consider amino acid composition, digestibility, and the digestibility of individual essential amino acids.

Do plant proteins have a low biological value?

Individual plant proteins may have lower traditional biological value scores than many animal proteins, but plant-based diets can still provide adequate high-quality protein when a variety of protein sources are consumed.

Is whey protein better than egg protein?

Both whey and egg proteins are high-quality protein sources. Their exact advantages depend on the context, including digestibility, amino acid composition, serving size, and individual dietary preferences.

Does a high biological value mean more muscle growth?

Not necessarily. Biological value is not a direct measure of muscle growth. Muscle development depends on total protein intake, amino acid availability, resistance training, energy intake, and recovery.

Conclusion

Biological value is a traditional measure of protein quality that describes how efficiently absorbed protein is retained and used by the body.

It helped establish the importance of amino acid composition and protein utilization in nutrition science. However, modern methods such as PDCAAS and DIAAS provide additional ways to evaluate protein quality and digestibility.

For people interested in muscle growth, biological value is useful to understand, but it should not be the only factor considered when choosing protein sources.

Focus on consuming enough total protein, obtaining sufficient essential amino acids, eating a varied diet, and combining adequate nutrition with progressive resistance training and recovery.

Use our Protein Need Calculator to estimate your daily protein needs, and explore different food combinations with our Protein Combining Score Calculator to learn more about complementary protein sources and overall protein quality.