Pea Protein vs. Whey: Similarities, Differences & How To Choose

Pea and whey are two of the most popular protein powders out there—but is one better than the other? Here's what to know about the absorption rates, benefits, drawbacks, and potential side effects of pea protein versus whey, as well as what to look for when choosing between these protein heavyweights.

Pea protein is a rising star in the protein powder world due to its versatility and neutral taste, which allows it to blend easily into smoothies, shakes, and other recipes. Additionally, pea protein is easy to digest1, making it an excellent option for those with sensitive stomachs or digestive issues.

A plant protein, pea protein is typically made from yellow split peas2 that undergo a rigorous refinement process3 to extract their protein. It's typically found in three forms4: pea flour, pea protein concentrate, and pea isolate.

Pea protein has a Protein Digestibility Corrected Amino Acid Score (PDCAAS)5 of 0.78 to 0.91 depending on the product, making it one of the easiest plant proteins to digest (though it's still harder to digest than animal proteins like whey, which have a PDCAAS score of 1.0). This rate allows your body to efficiently use pea protein's essential amino acids (EAAs) for muscle growth, repair, and recovery following workouts. In one study, participants who supplemented pea protein experienced a greater increase in muscle thickness6 compared to those taking a placebo.

"Pea protein is a complete protein, meaning it contains all nine essential amino acids (including the branched-chain amino acids leucine, isoleucine, and valine) necessary for muscle protein synthesis to occur. For this reason, pea protein is effective in building muscle7, and multiple clinical trials support this," says Emily Werner, Ph.D., R.D., CSSD, a registered sports dietitian.

However, some people don't consider pea protein a complete protein since it is low in some essential amino acids, like methionine. It also contains less of the amino acid leucine than whey, making it less effective at promoting muscle protein synthesis.

Pea protein's relatively complete amino acid profile8 makes it a fantastic option for vegans and vegetarians looking to meet their protein needs.

If you're lactose intolerant or have sensitivities to dairy, research shows pea protein is a safe and easily digestible alternative to traditional whey protein9.

Pea protein can boost the nutritional value of your diet since it's a rich source of essential nutrients9, including iron, fiber, and other vitamins and minerals.

In one systematic review and meta‐analysis, researchers found fewer markers of cardiovascular disease10 (the No. 1 killer worldwide11) in those who consumed more plant protein than animal protein.

Compared to animal proteins like whey and casein, pea protein is often lower in leucine12—an EAA that plays a critical role in muscle protein synthesis (MPS)13. Whey is about 12% leucine by protein content, while pea protein is closer to 8%.

As leading amino acid researcher Don Layman, Ph.D., previously told mindbodygreen of plant proteins, "You will always need more total protein, and that means more total calories, to be equal."

Consuming it in higher amounts or combining pea protein with other protein sources will be necessary to compensate for pea protein's lower leucine content.

Pea protein is generally considered hypoallergenic15 and is well-tolerated by most individuals. However, it's essential to be aware of potential allergies or sensitivities to legumes, such as peanuts. Check labels for any cross-contamination or allergen warnings if you have specific allergies.

Whey protein is among the most popular protein powders, and for good reason: It's digestible and contains all nine EAAs for a complete amino acid profile16.

Whey protein is a byproduct of cheese production and is extracted when milk separates into curds and whey. The liquid whey is then processed further to remove water, lactose, and minerals, leaving behind a concentrated protein powder loaded with amino acids essential for muscle growth and recovery.

As for the taste, whey protein has come a long way from its chalky reputation. Nowadays, there's no shortage of delicious products with various flavors to incorporate into your routine for a protein boost. 

There are two main types of whey protein: concentrate (WPC) and isolate (WPI). Whey concentrate is less processed17 and tends to have a lower protein content but offers more nutritional value since it contains more lactose and fat. Conversely, whey isolate is more refined than concentrate and contains less lactose and fat18, creating a product denser in protein per serving.

Whey protein boasts an impressive amino acid profile, including high levels of the BCAAs leucine, isoleucine, and valine. It also contains many other easy-to-digest essential and nonessential amino acids, contributing to its muscle-building prowess. 

"Whey is a complete protein, meaning it contains all nine essential amino acids necessary for muscle protein synthesis. In addition, it's the best protein in terms of digestibility, with a PDCAAS score of 1.0. For these reasons, whey is the best protein for building muscle," says Werner.

A major benefit of whey protein is that it's a complete protein as it contains plenty of all nine essential amino acids necessary for optimal muscle growth and repair.

Due to its high BCAA content, whey is highly soluble in the stomach's acidic environment19, allowing it to digest faster than other proteins.

Whey is rich in BCAAs, making it a popular choice among athletes and bodybuilders for promoting MPS and boosting recovery. Researchers have found that whey protein significantly benefits body composition20, especially when combined with resistance training and a balanced diet.

Since whey protein is derived from milk, it's unsuitable for vegans and those with lactose intolerance or dairy allergies. Some people may experience digestive discomfort or mild allergic reactions21 to whey protein. Choose alternative protein sources if you have known sensitivities or allergies to milk.

Whey protein contains lactose and milk proteins, so it's off the table for most people with lactose intolerance or dairy allergies. "Because whey protein is a milk derivative, there's a chance it will contain some lactose," states Werner.

Whey protein isolate has less than 1% lactose20, making it a safer option for those with lactose intolerance.

Here's how a 25-gram serving of whey protein isolate22 compares to a 27-gram serving of pea protein23, per the USDA:

Whey protein has long reigned supreme in the protein world due to its muscle-building benefits. Whey also offers a complete amino acid profile, high leucine content, and rapid absorption rate, making it an ideal choice for fueling muscle growth and recovery. "For someone who consumes an omnivorous diet, whey protein is the best option," explains Werner.

However, research shows that pea protein, with its balanced amino acid profile and impressive BCAA content, can be a good backup option for stimulating MPS and improving body composition24. For someone who can't consume whey, Werner adds that pea protein is one of the best of the plant protein options.

Both pea and whey protein can help those looking to lose weight. Whey protein has been shown to promote satiety25 and support weight loss by helping to retain lean muscle mass, and pea protein's high fiber content26 can help curb your appetite and prevent overeating. 

Instead of choosing one over the other, you can also consider incorporating various high-quality protein sources from whole foods and protein powder supplements for a well-rounded nutrient intake.

Whole food proteins such as vegetables, whole grains, legumes, nuts, lean meats, and seeds offer additional nutritional benefits, including fiber, vitamins, and minerals not found in isolated protein powders.

Reading nutrition labels is vital when choosing a high-quality protein powder. Look for brands that display their amino acid ratio on the package, contain little to no sugar, are free from additives, and provide a transparent breakdown of their nutritional quality. Don't settle for brands that keep you in the dark—choose the ones that lay it all out there for you to see, and choose what works best for your health and fitness goals.

Werner states that a high-quality protein powder will be third-party tested, contain all nine essential amino acids, and provide at least 20 grams of protein per serving.

RELATED READ: What To Look For In A Complete Vegan Protein Powder + 8 Top Options

Pea protein is rising in popularity due to its versatility and high digestibility, while whey protein is known for its complete amino acid profile and rapid absorption. Research reveals that both proteins can support muscle growth, weight loss, and body composition. When selecting a protein powder supplement, consider factors such as protein content, amino acid profile, and quality ingredients. 

Instead of choosing one protein over another, the best approach is to include several high-quality protein sources in your diet from a combination of whole foods and supplements for optimal nutrition.