Pea Protein vs Whey: Which One Should You Choose?

In recent years, pea protein has become an increasingly popular dietary supplement amongst everyone from vegans and vegetarians to your average, everyday health enthusiast.  This recent uptick in popularity, in turn, has lead many to wonder how exactly it stacks up against the OG of protein supplements -- whey.  

That’s why in this article, we’re doing an in-depth comparison of pea protein vs whey to give you a clear picture of what it is that sets each type of protein apart.  But before we dive too deep into our analysis, lets first talk about what pea protein and whey actually are and where they come from.     

Pea Protein vs Whey: What's The Difference?

Pea Protein

As the name implies, pea protein is derived from peas.  It’s usually extracted from yellow peas, although it can ultimately come from other kinds of peas as well.  

It’s plant-based, doesn't contain any major allergens, and is also gluten and lactose-free, making it a protein that most people are able to tolerate without issue.  

Like many types of protein powder, pea protein can come in isolate and concentrate form.  Pea protein isolate is generally around 80+% pure protein, meaning that much of the carbs, fat, and other nutrients have been removed during processing.⁽¹⁾

Pea protein concentrate, on the other hand, can have as little as 30% pure protein, meaning the other 70% of the mixture is made up of things other than protein.   

Whey Protein

Whey protein, is an animal-based protein derived from cows milk.  It makes up about 20% of all the proteins found in milk, while casein makes up the other 80%.   

Similar to pea protein, whey also comes in both concentrate and isolate form.  Whey protein concentrate is what you get when whey is separated from the casein protein that’s also in milk.

At this point, there is still a decent amount of lactose and fat leftover with the whey, which means that it may not be suitable for those with lactose issues -- lactose is a complex sugar that some people have trouble digesting.⁽²⁾

In contrast, whey protein isolate usually contains 90+% pure protein, meaning that most of the lactose and fat have been removed during processing.  People with less severe lactose issues can usually consume WPI without a problem.⁽³⁾

Pea Protein vs Whey: In-Depth Quality Comparison

Not only do pea protein and whey come from different sources but they also each have their own unique qualities as far as proteins go.  

On top of having different amino acid profiles and biological values, pea protein and whey also differ when it comes to how long it takes them to be absorbed during digestion.  

1. Amino Acid Content

One of the major differences between pea protein and whey has to do with their amino acid content.  Amino acids (AAs) are known as the building blocks of protein because they make up the structural foundation upon which proteins are built. 

Essential amino acids (EAAs) are amino acids that your body cannot produce on its and, therefore, must be obtained from dietary sources.  There are 9 essential amino acids in total and a protein that contains all 9 is known as a complete protein.⁽⁴⁾

When we’re talking about a protein’s amino acid content, we’re not only interested in whether or not it’s a complete protein, but we also want to know how much of each essential amino acid it contains. 

In other words, not only do we want to see that a protein contains all 9 essential amino acids, but we also want to see that all 9 of those EAAs are present in adequate amounts.⁽⁵⁾

In simple terms, a complete protein with a good distribution of all 9 essential amino acids is going to be a better quality protein in comparison to a protein that is lacking in certain EAAs.  

Pea Protein vs Whey

While pea protein technically contains all nine essential amino acids, it’s considered to be an inadequate source of methionine and cysteine, which is why it is sometimes classified as an incomplete protein.  

In contrast, whey is a complete protein and has a considerably well-balanced amino acid content, containing ample amounts of all 9 EAAs and particularly high concentrations of leucine, valine, and isoleucine -- the three BCAAs.  

Here’s how the amino acid contents of pea protein and whey break down; we’ve also included other types of protein for further comparison. 

Again, we’re only looking at essential amino acids here because they’re the most important.  Also, the essential amino acid tryptophan is not present on this list, however, both types of protein have been shown to contain moderate amounts of tryptophan in other studies. 

The following data comes from a 2018 journal article published in Amino Acids.⁽⁶⁾ All proteins on this list were tested in the isolate form, though purity varied from protein to protein:    

2. Muscle Protein Synthesis

Because they have different amino acid contents, pea protein and whey also affect the biochemical process known as muscle protein synthesis (MPS) in different ways.  There are numerous chemical pathways that are nutritionally, hormonally, and enzymatically dependent on MPS.  

When it comes to your muscles, they’re made up of proteins, which themselves are made up of amino acids.  Every day, somewhere around 1% of all your muscle proteins are broken down, requiring your body to replace them. 

It’s through the process of MPS that your body takes amino acids from your diet and builds new proteins to replace the old, broken-down ones.  

But in order for this to happen, a signaling event must take place, and no EAA is more important that than leucine when it comes to setting off this signal event. 

In fact, research shows that an ample amount of leucine is required to maximally stimulate MPS -- i.e. the more leucine that’s present in the protein source, the greater the degree to which it can potentially spike MPS.⁽⁷⁾

Pea Protein vs Whey

Compared to pea protein, whey contains almost 3 more grams of leucine per 100 grams of protein (5.7g vs 8.6g), which ultimately means that it may help to stimulate muscle protein synthesis to a greater degree than pea protein.  

3. Absorption

The time it takes for each type of protein to be broken down and absorbed into the bloodstream also differs for pea and whey protein.  While some proteins are absorbed rapidly in the gastrointestinal tract, it ultimately takes other proteins much longer to be broken down and utilized by the body.⁽⁸⁾

Pea Protein Vs Whey

Pea protein absorbs at a moderate rate of speed, usually completing absorption in 3 - 4 hours.  While that’s not necessarily slow -- a protein like casein, for example, can ultimately take up to 8 hours to be fully absorbed -- pea protein takes considerably longer to absorb in comparison to whey, which is usually absorbed within 90 minutes in the case of most isolates.  

4. Biological Value 

On top of absorbing at different speeds, pea protein and whey also have different biological values (BV).  BV is essentially a measurement of how much of a protein actually gets used by the body in the formation of new tissues, after all, is said and done.⁽⁹⁾

More specifically, biological value looks at post-meal nitrogen balances as a means of assessing a protein’s overall usability.⁽¹⁰⁾ A high biological value indicates that a protein source has a high usability and much of it is actually used in the formation of new tissues, while a low biological value indicates the exact opposite.  

Pea Protein vs Whey

In general, animal-based proteins have higher biological values in comparison to plant-based proteins.⁽¹¹⁾  For example, here’s how pea protein and whey stack up against both each other and a number of other protein sources.  

Pea Protein vs Whey: Which One Should You Choose?

When it comes to supporting your overall health, whey appears to be the better protein both in terms of its amino acid content and its biological value.  It has a more evenly distributed amino acid content and contains significantly more amino acids per 100g in comparison to pea protein (34.1g vs 23.6g in the one study we look at earlier).  

Additionally, whey also has a higher biological value, which ultimately means that more of it actually gets used in the formation of new tissue when compared to the same amount of pea protein.

On top of supporting your overall health, whey protein may also be a better protein source when it comes to supporting the muscle-building process, which after all, is why many people take protein supplements to begin with.  

Due to its high leucine content and well-rounded amino acid profile, whey has been shown to spike MPS to a greater degree than any other type of protein, which ultimately is the perfect scenario for maximizing your muscle-building potential.⁽¹²⁾

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On top of that, the quick absorption time of whey makes it the ideal protein to consume post-workout -- whey isolate is absorbed rapidly into the bloodstream, where it can be ferried off to muscles in need of repair within 90 minutes after consumption (compared to up to 4 hours for pea protein).  

Now with all that being said, it certainly doesn’t mean that pea protein has no benefits to offer, it’s just that whey protein is simply a higher quality protein at the end of the day.  

If we go back to our chart on the amino acid content of different proteins, we see that pea protein contains more total essential amino acids than many other plant-based proteins (including soy), which makes it a great choice for anyone who is vegan and/or those with allergies that prevent them from consuming whey.  

If you are going to supplement with pea protein, however, you’ll want to make sure that you’re mixing in other protein sources in your diet to make sure you’re getting an adequate supply of all 9 essential amino acids -- this is especially important for those on strictly plant-based diets.  

• References
  1. “Protein content and amino acid composition of commercially available plant-based protein isolates” Gorissen, S.H.M., Crombag, J.J.R., Senden, J.M.G., Waterval, W.A., Bierau, J. Amino Acids. Aug. 2018.
  2. “Whey protein concentrates and isolates: Processing and functional properties” Morr, C.V., Ha, E.Y.W. Critical Reviews in Food Science and Nutrition. Sep. 2009.
  3. “Protein – Which is Best?” Hoffman, J.R., Flavo, M.J. Journal of Sports Science and Medicine. Sep. 2004.
  4. “Protein – Which is Best?” Hoffman, J.R., Flavo, M.J. Journal of Sports Science and Medicine. Sep. 2004.
  5. “Protein quality assessment: impact of expanding understanding of protein and amino acid needs for optimal health” Millward, D.J., Layman, D.K., Tome, D., Schaafsma, G. American Journal of Clinical Nutrition. May. 2008.
  6. “Protein content and amino acid composition of commercially available plant-based protein isolates” Gorissen, S.H.M., Crombag, J.J.R., Senden, J.M.G., Waterval, W.A., Bierau, J. Amino Acids. Aug. 2018.
  7. “Rapid aminoacidemia enhances myofibrillar protein synthesis and anabolic intramuscular signaling responses after resistance exercise” West, D.W.D. Burd, N.A., Coffey, V.G., Baker, S.K., Burke, L.M., Hawlye, J.A., Moore, D.R., Stellingwerff, T., Phillips, S.M. The American Journal of Clinical Nutrition. Sep. 2011.
  8. “The rate of protein digestion affects protein gain differently during aging in humans” Dangin, M., Guillet, C., Garcia-Rodenas, C., Gachon, P., Bouteloup-Demange, C., Reiffers-Magnagni, K., Fauquant, J., Ballevre, O., Beaufrere, B. Journal of Physiology. Mar. 2003.
  9. “Protein quality assessment: impact of expanding understanding of protein and amino acid needs for optimal health” Millward, D.J., Layman, D.K., Tome, D., Schaafsma, G. American Journal of Clinical Nutrition. May. 2008.
  10. “Protein – Which is Best?” Hoffman, J.R., Flavo, M.J. Journal of Sports Science and Medicine. Sep. 2004.
  11. “Protein – Which is Best?” Hoffman, J.R., Flavo, M.J. Journal of Sports Science and Medicine. Sep. 2004.
  12. “Protein – Which is Best?” Hoffman, J.R., Flavo, M.J. Journal of Sports Science and Medicine. Sep. 2004.