Not All Protein is Created Equal

Not All Protein is Created Equal


Not all protein is created equal, but how do you determine which type is best for you? Variables including protein efficiency ratio, biological value, net protein utilization and protein digestibility corrected amino acid score (PDCAAS) were taken into account when examining different protein sources including numerous animal proteins and vegetable proteins. In this article we examine a review of different protein sources and discuss which options are best.

While there seems to be a debate in the nutrition field about how many grams of protein one actually needs in a day, studies have shown that both endurance and power athletes benefit from increased protein intake around 1.8/kg per body weight a day.

Not all protein is created equal. So the real question is not how much protein you should be consuming but what kind of protein you should be consuming for optimal performance and recovery.

The purpose of this study was to help determine key factors responsible for making appropriate choices on what type of protein (animal or vegetable) to consume in both animal and general populations.

Proteins are formed by amino acids. They are the major structural component of muscle and other tissues. However, that’s not all they do. Proteins are also used to produce hormones, enzymes and hemoglobins in order to be used by the body.

Enzymes are protein molecules within our cells. They act as catalysts, helping to speed up biological reactions. Digestive enzymes are a prime example. These particular enzymes help break down our food into smaller building blocks in order to be efficiently absorbed by the body.

Hemoglobins, on the other hand, are the proteins that give your red blood cells their pigment. It’s the protein in these red blood cells that carry oxygen from the lungs to the body’s tissues.

Amino Acids

There are about 20 amino acids total (12 non-essential and 8 essential). The absence of any of these amino acids will, unfortunately, compromise the body's ability to grow tissue.

That’s right, no gains for you brah.

This leads us to the question of what type of protein is best? In this review, we will discuss:

  • The variables used to rate protein quality
  • Protein sources (including animal protein, types of whey and vegetable protein)
  • High protein diets
  • Comparison of protein sources on human performance


What Protein is Best?

This study took a few variables into consideration when rating protein quality. These variables included:

  1. Protein efficiency ratio
  2. Biological value
  3. Net protein utilization
  4. Protein digestibility

Protein Efficiency graphic

#1: Protein Efficiency Ratio

The protein efficiency ratio (PER) is what this study used to determine how effective the type of protein is through the rate of animal growth. This was based on a trial of rats, not human growth (although humans and mice share virtually the same set of genes). (11)

This is done by taking the rats and feeding them a certain type of protein and then measuring their weight gained in grams per grams of protein in which they consumed. That value was compared to the standard value of casein protein, which has a value of 2.7. Therefore, if the value exceeds 2.7, it is thought to be a top protein source.

Protein's Biological value graphic

#2: Biological Value

This variable measures protein quality by examining nitrogen. It takes the nitrogen that’s used for tissue formation and divides it by the nitrogen absorbed from food. This number is then multiplied by 100 and used as a percentage.

But why does nitrogen matter?

Nitrogen is essential for the formation of amino acids in proteins.

This value demonstrates that protein with a high biological value will provide you with an abundant amount of amino acids. As you can probably guess, animal protein sources are higher than vegetable sources.

Net Protein Utilization graphic

#3: Net Protein Utilization

This variable is similar to biological value, but it takes the direct measurement of nitrogen absorbed. The difference between the two variables is that biological value is calculated from nitrogen absorbed and net protein utilization is from nitrogen ingested.

Protein digestibility

#4: Protein Digestibility Corrected Amino Acid Score (PDCAAS)

The Food and Agriculture Organization and World Health Organization (FAO/WHO) came together to determine the PDCAAS as the preferred way to measure protein value.

As you know, protein can be obtained via a number of different sources. So what are all these sources and how do you know measure which one is best?


Protein Sources

This study examines both vegetable and animal sources of protein. When you look at the effectiveness of a protein, you’ll want to look at it's quality and digestibility.

Most proteins from animal sources are considered “complete proteins” as they contain all of the essential amino acids (histadine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine).

Vegetable protein sources are often times incomplete because they lack a few of the essential amino acids (with soy being an exception). Vegetable proteins also don’t rank as high in biological value, net protein utilization, PDCAAS and protein efficiency ratio in comparison to animal proteins.

Protein from animal sources include eggs, milk, meat, fish and poultry. Consuming animal protein offers a variety of different benefits. For example, it has been shown that consuming animal protein during pregnancy can be extremely important for infants to have a normal body weight. (4)

But animal protein consumption in later stages of life are extremely valuable as well. One study demonstrated that elderly subjects who consumed meat showed greater  gains in lean body mass compared to subjects on a mainly vegetarian diet. (5)

What About Whey?

Whey is a complete protein abundant in the amino acid cysteine. Cysteine has the ability to enhance glutathione which contains key antioxidant properties. Whey protein is also abundant in BCAA’s (branched chain amino acids). These are vital in maintaining muscle tissue and preventing catabolic actions during training. (7)

Whey protein is widely known for its role in sports nutrition. But what is it exactly?

Whey is technically the liquid part of milk that remains after the coagulation of cheese processing. You could also think of whey as the liquid sitting at the top of your freshly opened yogurt. When it comes to whey, there are three main types:


Whey Powder

Whey Concentrate

Whey Isolate









Milk Fat





Whey powder is found in a number of food products, mainly used as an additive.

In order to make whey protein concentrate, the water, lactose and a few minerals are extracted. It has more proteins and compounds compared to whey protein isolate which is why it can be more attractive as a performance supplement for athletes.

Whey protein isolate is reduced in fat and lactose, which makes it a great option for lactose-intolerant individuals. The concentrations of protein in this whey are typically 90% or higher. 


Casein makes up 70-80% of the protein in bovine milk (milk from cattle). Casein is one of the most popular milk proteins out there today and is also considered a complete protein. Casein is able to form a micelle (a large particle) which forms a gel in the stomach, providing a slow release of amino acids in the bloodstream. This release can last for hours.

While whey is typically metabolized and used for protein synthesis or oxidation within an hour of ingestion, casein is a slow-digesting protein. (9) This means that it can be released into the bloodstream and take up to seven hours to fully digest.


Vegetable Proteins

Unlike animal proteins, vegetable proteins have to be combined together in order to provide all the essential amino acids. However, vegetable proteins do offer phytochemicals and fiber which are vital in a well-rounded diet. One of the most popular vegetable protein sources today is soy protein.

Soy Protein

Soy protein actually has a rather high rating from the PDCAAS scale of 1.0, the same as animal protein. Another interesting note to mention in regards to soy protein is that it’s a complete protein with a high protein of BCAA’s (unlike most vegetable proteins).

Soy is more than just a vegetarian option for protein. Feedlots around the country are using soybeans to feed their cattle.

Why is this bad?

Cattle are meant to graze freely on grass. Over the years, the demand of meat has greatly increased, which means farmers have resorted to a more convenient feed abundant in soy and corn (which contains a higher amount of leucine).

Cows fed a diet of soy and corn are stuck in overpopulated feedlots which means they are more susceptible to infection and disease. This leads to the use of antibiotics. This soy feed is typically supplemented by other fillers as well, including animal by-products and hormones.

We’re not talking the roids to get you swole like Anavar or DBOL, either. We’re talking about rBGH -- recombinant bovine growth hormone (which is why we push our number one ingredient: rBGH-free Whey Protein Concentrate).


High Protein Diets

While high protein diets are popular among athletic populations, they’ve been used in success with weight loss for the general population as well. There is still debate in regards to any potential side effects of a diet very high in protein. However, one study has shown that a diet high in protein, in fact, does not have any negative effects on kidney function. (10)


Comparison Between Protein Sources of Performance

There are many differences seen when comparing different types of protein. One study examined the levels of leucine 7 hours post-consumption of whey vs. casein. When comparing whey protein vs. casein, casein absorbed much slower.

However, casein consumption showed much higher leucine levels 7 hours later while there was no change in leucine levels seen in whey. Sure, whey stimulates synthesis of protein right away (by 68%) but most of it is oxidized shortly after. Casein, on the other hand, stimulates protein synthesis (by 31%) but results in a greater accumulation of protein over time. (8)


Bottom Line

Animal proteins prove to be of significant importance in infancy, mature adulthood and overall performance in general. In regards to athletic performance, casein and whey are the top protein sources. While casein is the most efficient in increasing protein synthesis over a long period of time, whey protein has a stronger initial impact on protein synthesis.


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