L-Isoleucine
L‑Isoleucine
Snapshot
L‑Isoleucine is a branched‑chain amino acid (BCAA) essential for protein synthesis, energy production, and regulating blood sugar during exercise.
What is L‑Isoleucine?
L‑Isoleucine is one of three BCAAs (alongside leucine and valine) that the body cannot synthesize and must obtain from dietary sources. It plays a direct role in muscle metabolism and glucose uptake.
Where It Comes From
Dietary L‑isoleucine is found in high‑protein foods such as meat, poultry, fish, eggs, dairy, soy products, legumes, and nuts. It is also available as a free‑form supplement, often combined with the other BCAAs in a 2:1:1 ratio.
Key Nutrients & Compounds
Supplemental L‑isoleucine provides the pure L‑isomer. In BCAA blends, it works synergistically with leucine to stimulate muscle protein synthesis and with valine to support energy metabolism.
Health Benefits
L‑Isoleucine supports muscle repair and growth by activating key enzymes in protein synthesis. It aids in energy production during prolonged exercise by serving as a gluconeogenic substrate and helps stabilize blood sugar levels by enhancing glucose uptake into cells.
Recommended Dosage
A common supplemental dose is 200–500 mg of L‑isoleucine per serving, with total BCAA intake ranging from 5 to 10 g per day, divided around workouts for optimal effect.
How to Use It
Mix L‑isoleucine powder or BCAA formulations into water or sports beverages and consume before, during, or after exercise sessions. Capsules can be taken with water at similar times.
Who Should Use It?
Athletes and active individuals seeking to enhance muscle recovery, reduce exercise‑induced muscle damage, and support energy metabolism will benefit most from L‑isoleucine supplementation.
Possible Interactions or Cautions
Excessive BCAA intake may lead to an imbalance of other amino acids. Individuals with branched‑chain ketoaciduria should avoid BCAA supplements. Those with kidney disease should consult a healthcare provider before use.
Final Thoughts
L‑Isoleucine is a vital component of BCAA supplementation, playing key roles in protein synthesis and energy metabolism. When used in appropriate ratios around exercise, it supports performance, recovery, and metabolic balance.
Scientific Studies
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Blomstrand, E., Eliasson, J., Karlsson, H. K., & Köhnke, R. (2006). Branched‑chain amino acids activate key enzymes in protein synthesis after physical exercise. Journal of Nutrition, 136(1 Suppl), 269S–273S.
https://doi.org/10.1093/jn/136.1.269S -
Shimomura, Y., Inaguma, A., Watanabe, S., et al. (2010). Branched‑chain amino acid supplementation before squat exercise and delayed‑onset muscle soreness. International Journal of Sport Nutrition and Exercise Metabolism, 19(6), 603–614.
https://doi.org/10.1123/ijsnem.19.6.603 -
Davis, J. M., Zhao, Z., Stock, H. S., et al. (2009). Central nervous system effects of ingested branched‑chain amino acids: implications for fatigue development. Amino Acids, 37(1), 65–71.
https://doi.org/10.1007/s00726-008-0097-4