Isoleucine is one of the three branched-chain amino acids (BCAAs), along with valine and leucine. As an essential amino acid, isoleucine needs to be consumed regularly and can be found naturally in dietary proteins like meat, fish, soy, and dairy.[1][2] Isoleucine serves as a building block for proteins, but it’s also thought to function as a signaling molecule in the body, involved in the regulation of protein, glucose, and lipid metabolism; glucose transport; and immune function.[3]
What is isoleucine?
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•Last Updated: May 16, 2025
Isoleucine is an essential branched-chain amino acid that must be consumed regularly and is found in dietary proteins such as meat, fish, soy, and dairy. It serves as a building block for proteins and plays a role in regulating protein, glucose, and lipid metabolism, as well as immune function.