Amino Acid
L-Isoleucine
Also known as: Isoleucine, Ile, BCAA
Essential branched-chain amino acid (BCAA) important for muscle protein synthesis, energy production during exercise, and immune function.
Last reviewed June 2026 · Evidence graded from peer-reviewed research, not editorial opinion. Educational only — not medical advice.
Primary uses
- Muscle recovery
- Exercise performance
- Blood sugar regulation
- Hemoglobin synthesis
How it works
- Activates mTOR pathway for muscle protein synthesis
- Oxidized in muscle for energy during exercise
- Precursor for glucose during fasting
- Supports hemoglobin production
Dosage
- Typical range
- 3-6 g daily
- Timing
- Pre/during/post workout
- With food
- With or without
- Duration
- Safe long-term
- Special populations
- Athletes, those in caloric deficit
Forms
- Powder
- Capsule
Safety
Common side effects
- Well tolerated
Contraindications
- MSUD
- ALS (controversial)
Products containing L-Isoleucine
Top-scoring supplements in our catalog that list L-Isoleucine on the label. Each product is graded on Formulate's ingredient-level rubric — dose accuracy, form, transparency, and third-party testing.
Evidence notes
Well-studied as part of BCAAs for exercise performance
Grade B: Some human trials support key claims; further confirmation needed.
Related in Amino Acid
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Medical disclaimer. This page is educational and does not replace advice from a qualified healthcare provider. Individual needs and risks vary — consult a professional before starting, stopping, or combining supplements, especially if you are pregnant or nursing, taking medication, or managing a health condition.