Leucine is an amino acid with powerful muscle building properties, due mainly to the role it plays with mTOR. In this video you'll learn about the benefits of supplementing L-Leucine and the top foods which contain Leucine.

I’m sure you are familiar with protein and just how important it is… people often say things like, proteins are the building blocks of the body.

In reality though, the true building blocks of the body are what the protein is actually made up of, which is a selection of various amino acids. All of these amino acids serve different purposes within the body.

Because of this, in order for a food to be considered an adequate protein source , a food needs to contain all nine of the essential amino acids necessary for the dietary needs of humans or other animals

As I said each of these essential amino acids has a different function in the body….. so what would happen if you were to cherry pick the amino acid with the greatest benefits to muscle gain, and supplement with that.

Then, you’d be supplementing Leucine, part of a family of three, known as the branched chain amino acids.

Although you will sometimes hear about people supplementing with BCAAs, many studies have actually shown leucine is so beneficial, that it is better to supplement with just leucine, versus a mix of the three BCAAs

This is why it is sometimes referred to as the 'main' amino acid due to the most popular benefit of BCAAs (muscle building) being mostly due to leucine.

Leucine activates the mTOR pathways, which then induces muscle protein synthesis aka the building of muscle.

Think of mTOR as the amino acid sensor of the cell. mTOR is sensitive to leucine concentrations.

Decreasing leucine concentrations signal to mTOR that there is not enough dietary protein present to synthesize new skeletal muscle protein and it is deactivated.

As leucine concentrations increase, it signals to mTOR that there is sufficient dietary protein to synthesize new skeletal muscle and mTOR is activated.


While the other two BCAAs do also activate mTOR, they are much weaker than leucine in doing so (and as such, 5g of leucine will be more effective than 5g mixed BCAAs).



When a food contains enough of all of the amino acids which we can only get through diet, it is said to be a complete protein source. But since these foods just need to meet certain minimum amino levels, they all have different levels of the different amino acids.

This is why a gram of ‘protein,’ can mean something different depending on its source

As an example, to be considered a complete protein , a food needs a minimum of just 7 mg of Tryptophan but it needs a minimum of 55 mg of leucine per gram of protein.

This also means that while a gram of protein from one source may have 55mg of leucine, a gram of protein from another source could have 85 mg of leucine.