Synopsis

Source of validity: Scientific
Rating (out of 5): 2

L-leucine is an essential branched-chain amino acid (BCAA) that has garnered interest for its potential role in reducing fatigue, particularly in athletic and physically demanding contexts. The scientific rationale for its use is primarily based on its involvement in muscle protein synthesis and energy metabolism. During prolonged or intense exercise, BCAAs, including leucine, are utilized by muscles for energy, and their supplementation is thought to delay the onset of central fatigue. Central fatigue is partially attributed to increased brain uptake of tryptophan, which leads to higher serotonin levels and a feeling of tiredness; BCAAs may compete with tryptophan for transport across the blood-brain barrier, potentially reducing this effect. Several studies have investigated BCAA supplementation in athletes, with mixed results. Some research suggests that BCAA and specifically leucine supplementation can reduce perceived exertion and mental fatigue during endurance exercise, but these effects tend to be modest. Most evidence is limited to sports and exercise contexts; there is little high-quality clinical evidence supporting leucine supplementation for fatigue in the general population or for chronic fatigue conditions. The overall quality of the evidence is low to moderate, with most studies having small sample sizes or methodological limitations. Thus, while there is a plausible scientific mechanism and some supportive evidence for leucine’s use in exercise-induced fatigue, the strength of the evidence does not currently warrant confident recommendations outside of this context.

More about l-leucine
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Other ingredients used for Fatigue

Other health conditions supported by l-leucine

Products containing l-leucine

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