Ingredient

Isoleucine

Neutral in 2

What is Isoleucine?

Isoleucine is one of the essential amino acids, meaning it cannot be produced by the body and must be obtained from food. It is typically found in foods such as meat, fish, eggs, and dairy products, as well as being a component in some plant-based foods and supplements.

It is mainly used in supplements and protein-rich products to support muscle metabolism and energy production. The health evidence indicates that isoleucine plays a role in muscle repair and growth. However, consuming it in high amounts through supplements may not provide additional benefits over obtaining it from a balanced diet.

When you see isoleucine on a label, it may sometimes be part of branched-chain amino acid (BCAA) blends in sports nutrition products aimed at enhancing athletic performance.

Commonly found in: protein powders, supplements, meal replacements, sports drinks, energy bars

What to watch

Excessive intake, especially through supplements, might cause an imbalance with other amino acids.

Benefits

Supports muscle repair and growth as part of the BCAAs.
Contributes to energy production and regulation of blood sugar levels.

FDA

Isoleucine is recognized as safe when consumed as part of a regular diet.

Research

While some studies support its role in muscle metabolism, evidence on supplementation benefits beyond a normal diet is mixed.

Vegan

Isoleucine in supplements might be derived from vegan sources, but in some foods, it could be animal-based.

Sources: Dietary Supplement Fact Sheet: Branched-Chain Amino Acids

Scout's take

Isoleucine is an amino acid that helps to improve skin hydration and elasticity. It is used in formulations to support skin repair and regeneration. It is generally considered safe for use in skincare.