Consuming 2 grams of leucine in young, healthy, active men is linked to measurable changes in the location of mTOR proteins within muscle cells within an hour, which are processes connected to the...

Pro

Against

Mechanism

Synthesis from 1 study

How it works

Leucine from food triggers a chain reaction inside muscle cells: it moves a growth signal to two key locations, turns it on, and tells the cell to start building more muscle proteins. This happens quickly after eating and directly links the amino acid to muscle growth.

Most probable mechanism

In Simple Terms

When leucine enters muscle cells, it turns on a molecular switch that moves a key growth regulator to two specific spots inside the cell — near the energy-producing lysosomes and the outer edge of the cell. Once there, this regulator activates a protein that tells the cell’s protein-making machines to start building more muscle proteins.

Causal chain

Leucine is absorbed from the bloodstream into skeletal muscle cells and reaches intracellular concentrations sufficient to bind leucine-sensing proteins.

Supported by evidence

which leads to

Bound leucine releases inhibition on the GATOR2 complex, enabling activation of Rag GTPases that direct the mTORC1 complex to the surface of lysosomes.

Verified by multiple studies

which leads to

Simultaneously, mTORC1 translocates to the peripheral membrane region of the muscle cell, where it encounters upstream activators and downstream substrates.

Verified by multiple studies

which leads to

At both the lysosomal surface and cell periphery, mTORC1 becomes fully activated and phosphorylates the ribosomal protein RPS6 at Ser240/244.

Verified by multiple studies

which leads to

Phosphorylated RPS6 enhances the efficiency of ribosomal translation initiation, increasing the rate of myofibrillar protein synthesis.

Verified by multiple studies

Evidence from Studies

Supporting (1)

Community contributions welcome

Leucine ingestion promotes mTOR translocation to the periphery and enhances total and peripheral RPS6 phosphorylation in human skeletal muscle

Randomized Controlled Trial

Human

2023 Feb

Contradicting (0)

Community contributions welcome

No contradicting evidence found

Gold Standard Evidence Needed

According to GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this specific claim, ordered from strongest to weakest evidence.

Source Study

Leucine ingestion promotes mTOR translocation to the periphery and enhances total and peripheral RPS6 phosphorylation in human skeletal muscle

Score: 43

DOI: 10.1007/s00726-022-03221-w

Similar Assertions

In young, healthy men who exercise recreationally, consuming leucine is linked to specific molecular changes in muscle cells that are thought to support increased muscle protein synthesis.

88%

Consuming 2 grams of leucine leads to a measurable increase in a specific molecular marker (phosphorylation of ribosomal protein S6 at Ser240/244) in skeletal muscle tissue within 30 to 180 minutes, which reflects increased activity of the mTORC1 signaling pathway.

87%

When young, healthy men who exercise regularly consume leucine, the molecular signals that promote muscle growth are stronger near the outer edges of their muscle fibers than near the center, suggesting that the location of these signals within the fiber may matter for how muscle responds.

78%

After consuming 2 grams of leucine, the level of a specific molecular signal in muscle cells at one hour is related to how quickly muscle proteins are built over the next three hours in young, active men.

76%

Taking leucine — a protein building block — might turn on muscle-building signals in your muscles, but if you're already training and eating enough protein, it won't actually make you stronger, bigger, or recover faster.

75%