Isoleucine is one of the three branched-chain amino acids (BCAAs), along with leucine and valine.
It is an essential amino acid, meaning it cannot be synthesized, and must be obtained through dietary intake.
Isoleucine plays critical roles in protein synthesis, muscle metabolism, immune function, and regulation of glucose and fatty acid metabolism.
Isoleucine is involved in promoting muscle growth and repair, modulating glucose uptake in skeletal muscle, and supporting mitochondrial function, especially under metabolic stress conditions such as hyperammonemia.
Isoleucine has been shown to enhance glucose uptake in muscle and intestinal tissues by upregulating glucose transporter proteins, and it can exert hypoglycemic effects independent of insulin.
Isoleucine is included in parenteral nutrition formulations for patients unable to meet their nutritional needs orally or enterally.
Deficiency of isoleucine can impair growth, immune response, and metabolic homeostasis.
Excessive intake of branch chain amino acids particularly isoleucine and valine, may contribute to adverse metabolic effects, including insulin resistance and obesity, as demonstrated in animal models.