ISOLEUCINE
Isoleucine is a branched-chain amino acid, one of the small building blocks used to make proteins. In the body, L-isoleucine occurs in proteins and in many living organisms, which is why the name may also be familiar from nutrition discussions. On a cosmetic ingredient list, however, ISOLEUCINE refers to the free compound, not to an oil or a botanical extract with that name.
ISOLEUCINE: what it is
Isoleucine is a branched-chain amino acid, one of the small building blocks used to make proteins. In the body, L-isoleucine occurs in proteins and in many living organisms, which is why the name may also be familiar from nutrition discussions. On a cosmetic ingredient list, however, ISOLEUCINE refers to the free compound, not to an oil or a botanical extract with that name.
It is different from leucine despite the similar names: they are distinct amino acids whose basic components are arranged differently. Isoleucine is essential in the human diet, meaning it must come from food. That biological role provides useful context, but it does not turn a leave-on or rinse-off cosmetic into a dietary supplement.
ISOLEUCINE: what it does in cosmetics
In cosmetics, isoleucine can be used in products for skin and hair. As a conditioning ingredient, it can be part of a formula designed to leave skin or strands feeling more pleasant; in hair products, it can also help address static electricity, the charge that makes individual strands separate and fly away.
Its role in a formula is not a treatment claim for hair loss, wounds, acne, or skin disease. The clinical reports located for isoleucine concern metabolic deficiency and oral supplementation in medical care, not the performance of isolated isoleucine applied to skin or hair. The realistic expectation is therefore product feel and conditioning, not a therapeutic result.
Products containing this ingredient
See which products include it and the name used in each composition.
