Whey vs. Soy Protein: A Comprehensive Comparison for Optimal Health

Protein powders, concentrated sources of animal or plant proteins, are wildly popular for various reasons. Not only are they easy to add to foods you already eat, but some are even fortified with other essential vitamins and minerals that you might not be getting via food sources. And, of course, getting enough protein is key for everything from helping with building muscle mass to weight loss. 

However, there isn’t a one-size-fits-all solution to picking a protein powder, as they are sourced from various plant and animal sources. The two most popular? Whey and soy. 

Meet the Expert

• Tara Collingwood, MS, RDN, CSSD, is a certified sports dietitian based out of Orlando, Florida.
• Keri Gans, MS, RDN, CDN, is a nutrition consultant, speaker, and author.

What Is Whey Protein?

Tara Collingwood, MS, RDN, CSSD, certified Sports Dietitian in Orlando, FL, explains that whey protein is an animal-based protein coming from dairy. “The milk is pasteurized and separated in proteins casein and whey. The whey protein is then processed more to remove the carbs, fat, and water, which leaves a powder that is whey protein,” she says. While whey protein isolate is processed to remove the lactose (milk sugar), whey protein concentrate may have small amounts of lactose.

Benefits of Whey Protein 

• It May Help Improve Athletic Performance: Keri Gans, MS, RDN, CDN, nutrition consultant, speaker, and author of The Small Change Diet, explains that whey protein is thought to be beneficial for athletes. “There is research to support that it may help improve athletic performance, increase strength and muscle mass,” she says. 
• It May Help with Psoriasis: Gans adds that whey has also been found to help with psoriasis by reducing itchy skin symptoms. 
• It May Aid in Weight Loss: Some studies have suggested that whey protein can help with weight loss, Gans points out.  
• It Is Packed with Nutrients and Amino Acids: Whey offers an abundance of nutritional value, says Collingwood. Not only does it contain all essential amino acids as well as branched-chain amino acids, but it is naturally abundant with calcium, which makes it great for your bones.
• It Is Easy to Add to Your Favorite Recipes: Collingwood also points out that it is the perfect addition to your favorite smoothies and recipes because it absorbs quickly, has a creamy texture, and a mild taste with minimal aftertaste. 

What Is Soy Protein?

While whey is a protein derived from an animal, soy is plant-based. “Soy protein comes from soybeans, which are a legume,” Collingwood explains. “Soy protein isolate is made from ground soybeans which are then processed into a powder.”

Benefits of Soy Protein

• It Might Help Manage Cholesterol: Gans points to scientific research that soy can be beneficial in terms of cholesterol. “Some studies have found that it may help lower the ‘bad’ LDL cholesterol and raise the ‘good’ HDL cholesterol,” she explains. 
• It Is Plant-Based: Because soybeans are a legume, soy protein is a great option for anyone on a plant-based diet, Collingwood points out.
• It Is Lactose-Free: If you are lactose intolerant, soy protein is a great option, as there are no dairy products involved. 
• It Is Packed with Nutrients and Amino Acids: Soy offers an abundance of nutritional value, says Collingwood. Not only does it contain all essential amino acids as well as branched-chain amino acids, but it is naturally abundant with calcium, which makes it great for your bones. 
• It Absorbs Quickly: Collingwood points out that soy can be easily added to a shake, smoothie, or other drink, as it absorbs quickly. 

Whey Protein vs Soy Protein: The Key Difference 

The primary difference between the two is what they are made of. “Whey is animal-based protein, and soy is a plant-based protein, so if someone has a milk allergy or is vegan, they are limited to soy,” Collingwood says.  

They also differ when it comes to taste. While whey has a creamy texture and mild taste with little-to-no aftertaste, soy can taste “nutty,” and “some report a sort of bitter aftertaste,” says Collingwood. Also, in terms of texture, it can be “a little more coarse and not quite as creamy as whey protein.”

Which Type of Protein Is Best for You?

If you are vegetarian or vegan, then soy is going to be the better option for you. However, if you can tolerate dairy, Gans suggests going with whey, as it “is most likely more effective for building muscle mass and increasing strength versus soy.” Collingwood adds that it is slightly higher in amino acid content and vitamin-mineral content. However, “soy has more naturally occurring phytonutrients which can be good for disease prevention,” she points out. Taste is also a consideration, as some people aren’t a fan of soy’s nuttiness. 

The Takeaway 

If you can tolerate whey protein, then you should gravitate toward it. However, if you are lactose intolerant or on a plant-based diet, soy is the way to go!

Everything You Need to Know About Adding Protein Powder to Your Diet