First, let’s consider what “high quality” protein really means, because this can really change depending on what nutrition goals you have.

Usually, high quality protein is protein that allows you to optimize the amount and speed that your body can perform protein synthesis aka producing new proteins. 

Here are 3 categories that allow you to measure whether a protein is of high quality or not.

1. Digestibility and absorption.

This factor considers whether the protein source is easy for your body to break down and whether it will be absorbed quickly. You’ve probably heard of “fast vs slow” digesting proteins, and if you have, you’ll know that both of these types of proteins are beneficial for different purposes. 

Faster digesting proteins like whey protein may be better post workout so that you can stimulate your body’s muscle protein synthesis ASAP. Slower digesting proteins like casein may be better at times where you don’t have regular access to high protein snacks. 

2. Essential amino acids (EAA).

Ideally, you want to choose protein sources that are high in all EAA’s. Why? Your body can’t produce 9 EAA’s, therefore it is crucial that you obtain these micronutrients from your diet in order to have these building blocks to stimulate muscle protein synthesis. 

3. Leucine.

Higher quality protein sources should be high in one EAA in particular, leucine. Leucine is a key EAA because it not only acts as an amino acid building block for the formation of protein, but it also acts as a signal to “turn on” muscle protein synthesis. 

So, how much leucine do you really need? 

Research currently shows that about 3g of leucine is needed to stimulate the optimal amount of protein synthesis [1].

But what does 3g of leucine look like? 

Here are some examples:

• 27g of whey protein, so around a scoop 
• 35g of casein protein, so a heaped scoop
• 164g of beef, so a small steak
• 5 eggs
• 180g of peas, so a bowl of peas

So, what does this mean for you? 

Well, you don’t need to go out and eat an entire bowl of peas to stimulate muscle protein synthesis. What we recommend is varying your protein sources so that you get a good amount of essential amino acids from your diet to help with protein synthesis. This is true for those who eat animal protein sources and for those of you who eat only plant based protein sources. Variety is good when it comes to nutrition, and especially with micronutrients.

What to remember

Although these 3 factors are important to consider when judging protein quality, it’s important to note that this does NOT mean that only high quality protein sources will benefit your body composition or performance goals. In fact, it remains unclear whether the differences in these factors actually translate to measurable differences in muscle-related adaptations.

What to do next

If you’re struggling to find recipes that contain these varied protein sources, we’ve already created an entire meal program for you! Check out our 4 Week Real Food, Real Quick Meal Plan!

References:

1. Churchward-Venne, T. A., Breen, L., Di Donato, D. M., Hector, A. J., Mitchell, C. J., Moore, D. R., Stellingwerff, T., Breuille, D., Offord, E. A., Baker, S. K., & Phillips, S. M. (2014). Leucine supplementation of a low-protein mixed macronutrient beverage enhances myofibrillar protein synthesis in young men: a double-blind, randomized trial. The American journal of clinical nutrition, 99(2), 276–286. https://doi.org/10.3945/ajcn.113.068775
2. MySportScience