Isoleucine (data page)
Isoleucine is one of the essential amino acids. It is part of the group known as branched-chain amino acids (BCAAs), along with leucine and valine. The body cannot make isoleucine, so you must obtain it from your diet.
Where it’s found
- Good sources include meat, fish, eggs, dairy products, soy, beans, lentils, nuts, seeds, and whole grains.
What it does
- Isoleucine helps build and repair body tissues, supports muscle growth, and provides energy during exercise.
- It also helps maintain a proper nitrogen balance in the body, which is important for muscle and metabolism.
How it works in the body
- Most of the energy-relating work of isoleucine happens in the muscles. During intense exercise, BCAAs can be used for energy and may contribute to overall energy production.
Structure and basics
- Isoleucine has the chemical formula C6H13NO2.
- Its IUPAC name is 2-amino-3-methylpentanoic acid.
- Like other amino acids, it has an amino group and a carboxyl group and is used in proteins in the left-handed (L) form.
Diet and amounts
- A balanced diet with enough high-protein foods usually provides sufficient isoleucine.
- Severe or prolonged malnutrition can lead to deficiency symptoms such as fatigue or slow growth, but this is rare in healthy people.
Supplements
- Some athletes take BCAA supplements, including isoleucine, to help with muscle recovery.
- High doses can cause stomach upset and other side effects, and supplements aren’t necessary for most people who eat a varied diet.
This page was last edited on 2 February 2026, at 16:05 (CET).