Ask Stacy: Which is Better, Whey or Plant Protein?

The protein debate has become a hot topic in recent years—and at the root of this debate is really a question about protein quality. That said, it’s important to keep in mind that protein quality isn’t the only factor in differentiating the two powders. Your goals and preferences should ultimately dictate which supplement is right for you—and ensuring you refuel adequately post-workout is something we’ve discussed here previously.  

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There are two main ways to determine protein quality: amino acid levels and ratios, and protein digestibility. When typically discussing whey protein, it is often considered the “gold standard” for bioavailability and rapid absorption of key amino acids for muscle protein synthesis and repair. These key amino acids specifically include the branched-chain amino acid (BCAA) leucine, which is a key regulator of skeletal muscle anabolism (muscle growth). However, leucine can’t do the job by itself as other essential amino acids are critical for reparation as well. Because whey protein is animal-based, it will naturally contain all essential amino acids, including the BCAAs that promote muscle recovery and synthesis. Because of whey’s higher concentration of BCAAs and its high biological value, some studies have noted more muscle protein synthesis for those who consume whey protein over plant-based soy. Whey is also particularly rich in calcium, healthy fats, and other beneficial compounds, such as omega-3 fatty acids. But, since whey is a dairy product, it does contain lactose, which is a type of sugar many people have a hard time digesting. This, along with the negative impact of the meat and dairy industry on our environment, may be viewed as the negatives of choosing whey.

When it comes to plant protein, there is research to indicate hemp, rice, and pea proteins do contain all essential amino acids, however, they also contain high levels of fiber and antioxidants, which might hinder adaptations to exercise if consumed immediately post-exercise. When comparing whey versus plant, you have to think about which one fits into your training and cultural context. Plant protein has a higher nutrient density and is more environmentally friendly than whey (win!), but it lacks all the essential amino acids to rock that rapid lean mass synthesis, which is where whey tends to shine.

Got a question for Dr. Stacy Sims? Submit it here and she might answer it in an upcoming “Ask Stacy” column on Triathlete.com.