Answers: What is Biological Value of Protein?

Did you know that the biological value of protein in whey can be over 100? It is one of the most usable proteins you can consume!

You are probably still wondering “but what is biological value?” Keep reading and you can find out!

When most people hear the term “protein,” they immediately think of a particular brand of supplement. First and foremost, I’d like to emphasize that supplements are not the focus of this article. Instead, we’ll look at different types of proteins and how they’re processed by the body. 

It’s worth noting, however, that the protein you get from supplements and the protein you can find in food is almost the same. The only exception is that certain powdered proteins are well-isolated and absorb more quickly than others.

Remember, supplements were designed to complement and improve your diet plan. They’re also handy and can be used in a pinch, such as after a workout or even for breakfast if you’re running low on calories.

The majority of your protein intake should still come from whole foods especially if you are trying to build or maintain muscle mass.

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What Does Biological Value (BV) Mean?

The biological value of protein means the nutritional effectiveness of the protein in a given food, shown as the percentage of the protein that is used by the body compared to either the total amount of protein consumed or the digestible protein that is available in the consumed food.

It captures how readily the digested protein can be used in protein synthesis in the cells of an organism. This means to get maximal rates of muscle protein synthesis, your protein intake should include high value sources of protein.

Let’s Talk Protein

Interesting fact- Protein comes from the Greek word proteios, meaning “primary” or “holding the first place.” A Dutch chemist Gerard Johann Mulder, coined the word protein in 1838.

As you probably already know, your body is technically a big, protein-based biological machine. Aside from water, protein is the most common element we see in the body and more importantly, it regulates a variety of vital processes. In a sense, protein is the building block of most of your tissues, enzymes, and hormones.

However, not all protein was made equal, different sources of protein have different amino acid compositions and different levels of protein retention. This means that the protein coming from different food sources, will be metabolized by the body in a slightly different way.

That is to say, there are high-quality sources of dietary protein, but also, low-quality ones. This should be taken into account when analyzing your own protein consumption especially for individuals who exercise.

How is the Biological Value (BV) of Protein Measured?

Proteins’ biological value is used to determine how well they are digested, absorbed, and preserved by the body after consumption. To put it simply, the biological value can be used to demonstrate the efficiency of the consumed protein.

Now, there are two primary measures that help us understand more about the biological value of proteins. Firstly, we have the amino acid profile of each protein-containing food.

For those of you who do not know this, proteins are made from amino acids. There are 20 amino acids, 9 of which are considered essential amino acids, meaning that the body needs them but can’t produce them on its own. That is to say that the more complete a certain food’s amino acid profile is, the higher its biological value.

The second thing used to measure the biological value of proteins is protein retention, or in other words, how long the protein stays in the body.

The BV Standard

Now, in nutritional science, the biological value of proteins goes on a scale from 0 to 100. Whole eggs (both yolk & egg white) are the standard for the biological value of proteins, measuring at 95-100 BV. If we take the yolk out of the egg, the biological value drops with 5-10 points, down to 90-95. With whole eggs being the golden BV standard, other foods are compared to them, in order to determine the bioavailability, as opposed to optimal quality protein (whole eggs).

What is the biological value of whey protein?: Whey/isolate protein supplements have a BV of 100+.

Now, this theoretical information is important, but it brings us to the next logical question.

What Are The Best Protein Sources?

Below, we have listed the biological value of protein for the most common protein sources we can find on the market nowadays, including both food and supplements:

1. Whey isolate protein blends – 100-150 BV
2. Whole eggs – BV 100
3. Cow milk – BV 91
4. Egg white – BV 88
5. Fish – BV 83
6. Beef – BV 80 
7. Chicken – BV 79
8. Casein – BV 77
9. Rice – BV 74
10. Soy – BV 59
11. Beans & legumes – BV 49
12. Peanuts – BV 43

Now, what this 12-point table means for you, is that your primary sources of protein foods should be the ones on the top of the list, which have higher biological value.

Nevertheless, you can combine those with other, lesser bioavailable sources of protein, such as plant protein. Just be aware that plant sources may not have all of your essential amino acids as most of them are not complete protein.

Incomplete proteins will only provide a fraction of amino acids required for your body to function properly, especially when trying to build or maintain muscle mass.

Ultimately, your best bet is to put a couple of high value food sources at the core of your protein intake, while also diversifying with a variety of other food sources. These different proteins will provide different amino acids profiles and ensure you have a more complete diet.

Factors That Affect The Biological Value of Protein (BV)

There are three major properties of a protein source that affect it’s biological value.

• Amino acid composition, and the limiting amino acid, which is usually lysine
• Preparation (cooking)
• Vitamin and mineral content

The amino acid composition has the most impact. Any essential amino acids (EAAs) missing from the diet will prevent the synthesis of any proteins that require them. If a protein source is missing some of these EAAs, then it will have a low biological value as the missing EAAs will not allow for proteins to be synthesized in the body. You can also supplement EAAs directly with a product like this.

For example, if a muscle protein requires phenylalanine (an essential amino acid), then this amino acid must be provided in the diet for the muscle protein to be produced. If the current protein source in the diet has no phenylalanine in it the muscle protein cannot be produced, giving a low usability and BV of the protein source.

Similarly, if amino acids are missing from the protein source which are particularly slow or energy consuming to synthesize this can result in a low biological value.

Certain methods of food preparation also affect the availability of amino acids in a food source. Some food preparation may damage or destroy some EAAs, reducing the BV of the protein source. For example, cooking foods at very high temperatures can reduce the BV of the protein contained in them.

Many vitamins and minerals are vital for the correct function of cells in the test organism. If critical minerals or vitamins are missing from the protein source this can result in a massively lowered BV. Many BV tests artificially add vitamins and minerals (for example in yeast extract) to prevent this.

Criticism For Using the Biological Value of Protein

Because BV only measures the amount of protein retained in the body, some critics believe it is not a great way to gauge protein value. For example, research indicates that although whey protein has a high biological value, it digests so quickly that it may enter the bloodstream and convert into carbs through gluconeogenesis.

This means that even though the amino acid concentrations increase, the oxidation rate also increases. Hence, there is no change in overall protein balance.

So, although the biological value of protein like whey is high, it absorbs so rapidly that your body can’t use it all. Issues like this with whey bring into question how valid measuring the biological value of protein is for protein consumption.

Additional Criticism

BV measurement does not consider other vital factors that influence the digestion and interaction of the protein with other foods. Essentially, it only measures the protein maximal potential quality and not how usable it is to your body.

Additionally, as you increase your protein intake, the biological value of protein you consume goes down. As a result, the BV goes down if you consume protein beyond your required levels.

Our Thoughts on These Criticisms

Although these are valid points, we acknowledge that whey should not be a primary source of protein. Also, suppose your protein intake is above your body’s requirements. In that case, protein quality becomes less relevant, except for meeting calorie intake goals.

Other Methods For Measuring Protein Value

There are many other major methods for measuring how readily protein is utilized. These include:

• Net protein Utilization (NPU)
• Protein Efficiency Ratio (PER)
• Nitrogen Balance (NB)
• Protein digestibility (PD)
• Protein Digestibility Corrected Amino Acid Score (PDCAAS)
• Digestible Indispensable Amino Acid Score (DIAAS)

These all hold specific advantages and disadvantages over measuring biological value of protein.

Conclusion

The biological value of proteins (BV) tells us more about the amino acid content of each food, as well as how long its protein is retained in the body and how efficiently it is used. Animal sources of protein appear to be superior, due to the better amino acid profile, as well as overall bioavailability. This is why, if you are not vegetarian or vegan, foods like beef, eggs, fish, and chicken, should make up the majority of your daily protein intake.

As long as your complete protein intake is at or above about 1 gram per pound of bodyweight and includes a variety of proteins you shouldn’t be too concerned about the values above. That doesn’t make the information any less interesting though!

You can learn more about complete protein here!

If you have any questions regarding the biological value of protein feel free to drop them in the comments below!