Isoleucine

    Written by:
    Katie Jantz

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    Nick Milazzo
    Last Updated: October 13, 2023

    Isoleucine is one of the three branched-chain amino acids (BCAAs). It is an essential amino acid. Isoleucine is required for muscle protein synthesis, and it may help to reduce post-exercise muscle soreness and markers of muscle damage when taken as part of a BCAA supplement. However, whether isoleucine holds any special merit as a supplement on its own is unclear.

    Overview

    Dosage information

    The recommended daily allowance (RDA) of isoleucine established by the Institute of Medicine is 19 mg of isoleucine per kilogram of bodyweight (mg/kg) daily. This is the average amount of isoleucine that meets the nutritional requirements of most people.[1]

    Isoleucine can be supplemented individually, but it is more commonly taken as part of a BCAA or complete protein supplement (e.g., whey protein, soy protein). There is currently no strong evidence to support the use of isoleucine as a supplement alone and no well-established dosing.

    In rat studies, dosages of 0.3–0.45 mg/kg were effective for reducing blood glucose and increasing muscle cell glucose uptake.[2][3] This could be extrapolated to a human dose of 48–72 mg/kg (for a 150 lb person, 3.3–4.9 g), but these beneficial effects have not yet been clearly established in clinical trials.

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