You may have heard people claim that those who don’t eat meat, won’t be able to get all the required protein they need to build muscle.
They normally go on to express that plant based protein sources are not complete proteins and do not contain a full amino acid profile, which can be misleading.
In fact all plant protein sources are complete and do contain a full amino acid profile. The confusion I believe people come across is that although, yes, plant protein sources are complete proteins, most are deficient in at least one of the 9 essential amino acids and therefore are considered incomplete.
What’s an amino acid?
Protein plays a crucial role in almost all biological processes and amino acids are the building blocks of it. When you digest protein, your body will break this down into amino acids to make proteins to help the body:
- Break down food
- Repair body tissue
- Perform many other body functions
What is an essential amino acid?
Essential amino acids are those that cannot be made by the body on it’s own and as such must come from food.
There are 9 essential amino acids: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.
Of all the amino acids, there is 1 that is considered king when it comes to building muscle, Leucine. Before we dive into the benefits of leucine in muscle growth, first lets cover some basics.
When you lift weights, your body enters a catabolic state, whereby skeletal muscle protein degradation is increased, the overall effect is a negative net protein balance.
Post workout when you consume protein, this flips the switch to stimulate muscle protein synthesis and begins the process of repairing and building new muscle.
Why is Leucine king?
It is the rise in blood concentrations of amino acids and particularly the level of Leucine in your blood that stimulates protein synthesis.
Leucine is the most abundant of the three branched chain amino acids (BCAAs) in muscles (the other two are isoleucine and valine) and has a unique ability to stimulate skeletal muscle protein synthesis and activate major components of the muscle building pathway.
How much Leucine do you need to stimulate protein synthesis?
The ideal amount of Leucine is up for debate, but in studies using single doses, just 2.5g of Leucine stimulated protein snythesis. In long-term studies, the recommended outcome is to consume 8 or more grams of Leucine per day in divided doses of at least 2.5mg at each meal.
and THIS is where I believe the “complete” amino acid profile of plant based protein sources comes into question.
Most plant based protein sources are deficient in the no1 vital amino acid to trigger protein synthesis. It’s not to say that protein synthesis wont occur with plant based sources, but it’s probably not the most optimal if your goal is to build muscle.
Check out the Leucine content of these popular vegan protein sources, remember you likely need at least 2.5g of Leucine for the best results.
- Mycoprotein (QUORN) 0.95g of Leucine per 100g
- Chickpeas 0.63g of Leucine per 100g
- Lentils 0.62g of Leucine per 100g
- Quinoa 0.33g of Leucine per 100g
- Tofu 0.73g of Leucine per 100g
Should you supplement with BCAA or Leucine?
Depending on how often you eat, it’s quite possible that over the course of a day you will hit the required 8g of Leucine, which is why there are many vegans out there who don’t supplement with BCAA that have great physiques, however you will unlikely be hitting the minimum requirement of Leucine per single dose (each meal), to maximally stimulate protein synthesis.
Personally, I do supplement, first and foremost I focus on whole foods across the day, but alongside each meal I will supplement with either 10g BCAA or 5g Leucine to ensure that I am exceeding that threshold and increasing my chances of building lean tissue.
Vegan Leucine Supplements
Be careful when choosing your BCAA or Leucine supplements, most that you will see come from animal sources. Instead look for “fermented” BCAA and if in doubt always contact the vendor.
My go to is MyProtein.com (use code MARKFOX10 at checkout for a discount) Fermented BCAA 4:1:1 or Fermented Leucine..whatever you do, DO NOT get the unflavoured Leucine, you will cringe and shudder every time you try to drink it.
NOTE: supplementing with just Leucine alone will not result in optimal effects if the your diet is low in protein. This is because other BCAAs (isoleucine and valine) will be preferentially oxidized and lead to a BCAA imbalance that compromises anabolism. Therefore, if total protein intake is low, supplement with all three BCAAs.
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