Plant-based protein: can it match animal protein for athletic performance?

Adopting a plant-based diet is a trend that continues to grow in popularity. However, for people focused on muscle growth and strength due to their athletic pursuits, there may be concerns about whether their muscle development and sports performance are being compromised by eating predominantly protein from plant foods. In this podcast episode, I’ll explore the fundamental differences between animal and plant-based proteins, discuss the primary supplements available for each type, and review recent research on the effect of these different protein sources on muscle growth, strength and physical performance.

Links referred to in the podcast

• Systematic review of animal vs plant protein on muscle mass, strength and physical performance https://pubmed.ncbi.nlm.nih.gov/39813010

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Transcript

Adopting a plant-based diet is a trend that continues to grow in popularity. However, for people focused on muscle growth and strength due to their athletic pursuits, there may be concerns about whether their muscle development and sports performance are being compromised by eating predominantly protein from plant foods. In this podcast episode, I’ll explore the fundamental differences between animal and plant-based proteins, discuss the primary supplements available for each type, and review recent research on the effect of these different protein sources on muscle growth, strength and physical performance.

Protein is essential for the body as it is composed of amino acid building blocks that can be resynthesised into various functional and structural proteins. Some amino acids are essential because the human body either cannot produce them or cannot produce them in sufficient quantities. Animal-based protein foods typically supply biologically complete protein containing all the required amino acid building blocks.

Plant-based proteins are also valuable sources of protein. Although some plant proteins may be low in certain essential amino acids, combining different sources can provide a complete amino acid profile. For example, rice and beans together form a 'protein complete' meal. Furthermore, some plant proteins, such as soy and quinoa, are considered complete protein sources. Therefore, a vegetarian diet can provide adequate protein from a nutritional standpoint meeting all of a person’s protein needs.

But what about in a sports setting when protein requirements are typically higher and the athlete has a stronger focus on muscle growth and strength? This can be where athletes turn to protein supplements to help meet higher protein needs.

The main type of animal-based protein supplements on the market are dairy-based, including the ever popular whey and casein. Whey protein is absorbed faster than casein and is often used due to its availability as a byproduct of cheese manufacturing.

Whey protein is noted for its strong anabolic effect on muscle growth due to its high leucine content. Leucine is an essential branched-chain amino acid that activates muscle protein synthesis via a signalling pathway called mTOR.

For those interested in plant sources of protein, soy protein is a perennial popular pick. Soy protein is rapidly digested and comes available in a supplement form as both soy concentrate and soy isolate.

Legume sources of protein are growing in popularity for those seeking other plant-based sources of protein. One example is pea protein powder which is absorbed faster than casein but slower than whey protein. Pea protein powder is naturally vegan, gluten-free, dairy-free and is very low in its allergenic potential so it works in almost any diet.

Even lower-quality proteins, such as those from wheat, can elicit a significant muscle protein synthesis response if consumed in large enough amounts. This suggests that overall adequate protein intake from a varied diet may be more important than the specific source of protein.

Certainly, the world of elite sport is replete with athletes who are following vegetarian or vegan diets. Clearly, it is possible to excel at the highest level of sport without needing to eat animal-based foods if that is an important health, environmental, religious or ethical issue for you.

When comparing plant vs animal protein on muscle protein synthesis in clinical trials it is important to know what the protein sources were especially for the plant-based proteins because of their highly variable amino acid compositions. For example, a recent review found that animal and plant proteins were similarly effective for maintaining muscle mass, yet all trials in this review provided soy protein as the plant protein intervention. So, you can’t apply these findings to all plant protein sources and assume every plant protein is on par with soy protein.

That leads into the new research I want to profile in this podcast which is a systematic review published in January of this year that set out to see how a range of animal and plant-based protein diets compared for their ability to improve muscle mass, muscle strength and physical performance in both older and younger adults.

In all, 43 randomised controlled trials were included in the review. Each trial included a direct comparison of an animal versus a plant protein intervention where the additional protein was given either by a supplement or a whole diet. For studies that that used supplemental protein, it was milk protein as the source for the animal protein and for plant protein supplements, it was soy, rice, pea, oat, potato and chia seeds as the protein source. For wholefood diets, varied protein sources were used including meat, fish and dairy foods for the animal protein study arm or a vegan diet or high plant-protein diets for the plant-based protein arm of the study. 

Trials ran from 4 weeks up to 2 years. Ten trials were conducted in adults over the age of 60 with 32 trials in adults under 60 years and included over 1,500 participants. And I’ll link to this study in the show notes https://pubmed.ncbi.nlm.nih.gov/39813010

So, what did the study find? When comparing all the animal protein interventions to all the plant protein interventions, animal protein had a slight edge for building muscle mass compared to plant protein. But for more functional measures of muscle strength and general athletic performance there was no significant difference between the protein sources.

But even the finding that there was a small edge for animal protein on building muscle mass has some disclaimers. It was only seen in adults under the age of 60 and only in studies that did not use soy protein as the comparison plant protein source. When soy protein was the plant protein focus, it seemed to perform just as well as the animal-based protein sources. This shouldn’t be too surprising because soy protein is considered a high-quality plant protein source and is a ‘go to’ protein food for many people on vegetarian diets. 

And it could even be that the reason that the other plant-based protein foods may not have worked quite so well on muscle mass in those under 60 is simply because there were a lot less trials compared to those that used soy, making it harder to be confident that you’re seeing a real effect or not.

So, let’s wrap all this up. What to make of this new research? If I had to provide a firm conclusion based on the whole research field, I would say that when it comes to muscle mass, animal protein in general may have a small edge. But that may apply only in certain circumstances depending on your age, activity levels and even what plant protein source you want to compare it to. But muscle mass is just one measure of athletic performance goals. What really matters is how a higher-protein diet translates to strength and physical function and the research is saying that for that, protein source is likely not that important – what matters more is hitting your protein goals and getting that from a variety of protein sources. 

If you follow an omnivore diet, then there is no shortage of high-quality protein foods and supplements to choose from. If you’ve adopted a vegetarian or vegan lifestyle, then probably the only consideration is to perhaps give soy foods and perhaps a soy protein supplement a higher priority in your diet.

But let’s not forget that all these recommendations are only on the diet side of the performance equation, because they won’t be of a lot of use to you without the other side of the equation: and that’s resistance training and there is no natural supplement that will give you a shortcut to hard work in the gym. 

So that’s it for today’s show. You can find the show notes either in the app you’re listening to this podcast on, or else head over to my webpage www.thinkingnutrition.com.au and click on the podcast section to find this episode to read the show notes. 

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I’m Tim Crowe and you’ve been listening to Thinking Nutrition.