Whey vs. Plant Protein: Which One Should You Choose?

With many millions of regular users, protein powder is amongst the most popular dietary supplements in the world.  However, there are all different kinds of protein powders out there, and deciding which one is right for you can often be a less than straightforward task.  

For many people, the choice ultimately comes down to whey protein -- the OG of protein supplements -- or plant protein, of which there are a number of different types.  

But what exactly is the difference between whey vs plant protein and is one kind really better than the other?  Well, in order to answer these questions and more, we’re going over some of the main things that set each type of protein apart.  Before we dive too far into our comparison though, let’s first discuss what kind of factors affect the overall quality of a protein.

What Factors Affect The Quality of a Protein?

There are several factors that help set different kinds of proteins apart from one another.   On top of having different amino acid profiles, different kinds of proteins can also vary significantly when it comes to their biological values and ultimately also their digestibility.  

All of these factors (both by themselves and together) affect the overall quality of a protein, with some kinds of proteins possessing more favorable characteristics than others.  

Factor #1: Amino Acid Profile 

One way in which scientists evaluate the overall quality of different protein sources is by looking at their amino acid profiles.  Proteins themselves are actually made up of amino acids (AAs) and at the end of the day, different kinds of proteins contain different quantities of amino acids.    

Essential amino acids (EAAs) are the most important, as they cannot be produced within the human body and therefore must be obtained from dietary sources -- you ultimately need an adequate supply of all 9 EAAs in your daily diet in order to support the overall health and function of your body.⁽¹⁾

A protein that contains all 9 EAAs is known as a complete protein and is considered superior in quality in comparison to a protein that is lacking 1 or more EAAs (AKA an incomplete protein).⁽²⁾

Even amongst complete proteins though, the exact levels of each particular EAA can vary significantly from one protein to the next, which can also affect the overall quality of the protein.  

In other words, even when we’re looking at proteins that do contain all 9 essential amino acids, some kinds of proteins ultimately have more well-rounded amino acid profiles than others.  

Factor #2: Bioavailability

On top of its amino acid profile, another common measurement scientists rely on when evaluating the quality of a protein is its biological value (BV).  

In simple terms, BV is a measurement of how much of the protein actually gets used up by your body in the formation of new tissues when all is said and done (aka its bioavailability).  More specifically, it looks at how a protein affects the body’s nitrogen balance as a means of making this assessment.⁽³⁾⁽⁴⁾

A protein’s biological value can range from anywhere between 0 to well over 100, with high values denoting that much of the protein actually gets used up in the formation of new tissue, while lower values suggest that the body’s overall utilization of the protein is less efficient.  

Factor #3: Digestibility

Another factor that affects the overall quality of a protein is its digestibility.  The process through which proteins are converted by the body into amino acids starts in the stomach, where digestive enzymes begin breaking down the peptide bonds that keep each protein molecule bound together.⁽⁵⁾

After these bonds are dissolved, what you’re left with are known as polypeptides, which are chains of amino acids connected to one another. From there, these polypeptides travel to your small intestine to where additional digestive enzymes go to work breaking down polypeptides into single amino acids that can be readily used up by the body.⁽⁶⁾

While all proteins go through this general process, there are several things that make each type of protein unique when it comes to digestion.  First, different kinds of proteins have different rates of digestions, with some being broken down rapidly (in as little as 60 - 90 mins), while others are digested much more slowly (6 - 8 hours).  

On top of the varying digestion rates, some kinds of protein can also be more difficult for certain people’s bodies to breakdown.  On top of leading to a less efficient overall utilization, a poorly digesting protein can also cause side effects like diarrhea, nausea, and vomiting.  

Whey Protein vs Plant Protein: What’s The Difference?

⫸What is Whey Protein?

Whey protein is one of the 2 types of proteins found in cow’s milk and is a natural byproduct of the cheese manufacturing process -- it’s contained in the translucent liquid that remains after coagulation and the removal of cheese curds.     

This remaining liquid is then purified to varying degrees in order to create whey protein powder.  During this purification process, some of the carbs and fat that are also present in the leftover cheese byproduct are removed, although how much is actually taken out depends on the manufacturing process itself.  

Whey concentrates can range anywhere from 30% -- 80% pure protein when all is said and done.   Whey isolates go through significantly more processing and as a consequence, are usually 90+% pure whey -- ultimately, that means that isolates contain significantly fewer carbs and fats in comparison to concentrates.    

Amino Acid Profile

Whey protein is a complete protein and has a considerably well-balanced amino acid profile, having moderate to high concentrations of all 9 essential amino acids.⁽⁷⁾

It also contains considerably high amounts of leucine, valine, and isoleucine -- 3 EAAs which are classified as branched-chain amino acids (BCAAs) due to their molecular structure.⁽⁸⁾

Bioavailability

Whey protein has an incredibly high biological value, which again, means that it’s efficiently used up by the body in the formation of new tissues.  In fact, whey protein has the highest biological value of any type of protein that’s been formally measured, with whey concentrate coming in at a BV of around 100 and whey isolates measuring more in the vicinity of 140.⁽⁹⁾

To give you a basis for comparison, some of the highest biological values found in other protein sources include eggs (BV = 100), beef (BV = 80), and chicken (BV: 79).  

Digestibility

Whey protein is a fast-digesting protein, being absorbed in as little as 60 - 90 minutes in the case of most isolates, though concentrates will generally take a little longer to digest ( 2-3 hours).⁽¹⁰⁾

As far as digestibility goes, whey protein does contain lactose, which is a carbohydrate that some people have trouble digesting -- lactose intolerance is the most common form of carb intolerance in the world.  

With that being said, because whey isolate is 90+% pure, it contains very little lactose, meaning that it’s usually well-tolerated in those with less severe lactose issues.   Those who do not have any dairy-related sensitivities should be able to consume both whey concentrate and isolate without issue.  

⫸What is Plant Protein?

Plant protein is just that -- protein that is derived from a plant-based source.  Unlike whey protein which comes exclusively from cow’s milk, plant protein can come from a variety of different sources, all of which with their own unique properties.  

As with whey, the purity of plant protein can also vary significantly.  Some isolates may be 80+% pure protein, while other plant-based concentrates may be 30% or even less in some cases.  

There are ultimately a number of different kinds of plant-based protein powders currently on the market.  Some of the most popular ones here in the U.S. include:

• Soy protein
• Rice protein
• Pea protein 
• Pumpkin seed protein
• Quinoa protein
• Sweet Potato Protein
• Hemp Protein

Amino Acid Profile

While some plant-based proteins like soy and quinoa for example are considered complete proteins, many do not contain all 9 essential amino acids.⁽¹¹⁾

Even amongst those that are technically considered complete, many have less than ideal amino acid profiles, containing only small amounts of certain EAAs.

For example, although pea protein technically contains all nine essential amino acids, it’s considered to be an inadequate source of methionine and cysteine, which ultimately means that it has a less than well-balanced amino acid profile.⁽¹²⁾

That’s why many plant-based protein powders are actually a mixture of different plant-based proteins -- mixing them together helps to improve their amino acid profile and assure that all EAAs are present in adequate amounts.  Here’s how the amino acid profiles of whey and a number of different plant-proteins breakdown.  

Bioavailability

In most cases, plant proteins have lower biological values in comparison to animal-based proteins, though BV can vary significantly event amongst plant-based proteins.⁽¹³⁾  Here’s how some of the highest-ranking animal-based proteins stack up against some popular pant proteins: 

Digestibility

Unlike whey protein, which does contain a carbohydrate that some people have trouble digesting, plant protein is is well-tolerated in the vast majority of the population, making it a suitable protein source for just about anyone.    Most plant proteins digest at a moderate rate, usually completing digestion within 3 - 4 hours.⁽¹⁴⁾

Whey vs. Plant Protein: Which One Should You Choose?

When it comes down to choosing between whey vs plant protein, there are multiple factors to consider, however, deciding which protein is right for you ultimately depends on what your goals, needs, and preferences are.

⫸Which One is Better For Building Muscle?

When it comes to building muscle, no protein is better suited than whey.  With a considerably well-rounded amino acid profile featuring high concentrations of the important EAA leucine, whey has been shown to increase muscle protein synthesis (MPS) -- the central biochemical process behind muscle growth -- to a greater than any other type of protein.⁽¹⁵⁾  Ultimately, the greater your levels of MPS are, the greater your muscle-building potential.  

Now that’s, not to say that you can’t also build muscle with plant protein -- you most certainly can -- it just means that whey is the more effective protein when it comes to the muscle-building process.  

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⫸Which is Better For Digestion?

If you’re someone who has dairy-related digestive issues, plant-protein is the safe choice, as it’s well-tolerated in the vast majority of the population; whey protein does contain the carbohydrate lactose, which some people do have trouble digesting.  

Those with more severe intolerances should steer clear of whey, however, 90+% pure isolate forms contain very little lactose and are usually well-tolerated in those with less severe issues.  With that being said, whey protein is well-tolerated in most people who do not have dairy-related digestive problems.  

⫸Is One Better For the Environment?

When it comes to considering environmental factors, whey protein is environmentally friendly in the fact that producers capitalize on a byproduct of the cheese and yogurt manufacturing process that would otherwise go to waste. 

 However, because it does come from cow’s -- the number one agricultural sources of greenhouse gases -- whey is considerably less environmentally friendly in comparison to plant proteins, which have little to no environmental effect when organic farming practices are in place.  

Wrap Up

There are several factors that set whey and plant protein apart from one another.  In addition to having different amino acid profiles and biological values, they also have different effects on the digestive process.  

While there are certain benefits and drawbacks to each type of protein, deciding which one is right for you ultimately depends on your goals, needs, and preferences.  

Due to its well-rounded amino acid profile and high bioavailability, whey protein is considerably well-suited for the muscle-building process.  

Plant protein is perfect for those who have issues with dairy-based foods.  It’s well-tolerated in the vast majority of the population and mixing different plant proteins together can help to balance out the amino acid profile (which can also help to increase its effects on the muscle-building process).   

• References
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