Leucine
Leucine is an essential branched-chain amino acid (BCAA) that comes from protein foods. It is mostly studied for its part in building muscle protein.
Also listed as L-Leucine
Does leucine alone improve muscle in older adults?
A 2022 review of 17 randomized trials involving 1,418 older adults found no significant improvement in lean mass, handgrip or leg-press strength with isolated leucine. Some combined supplements improved grip strength and walking speed, but their other ingredients prevent attributing the benefit to leucine alone. 1
What about recovery after exercise?
In 20 recreationally active young men, a mixture providing 4 g essential amino acids, including 1.6 g leucine, three times daily for four days improved recovery of combined muscle-force measures. It did not significantly improve soreness or integrated muscle protein synthesis versus placebo. This small trial supports further study of the mixture, not a proven effect of leucine alone. 2
Effects by health goal
Open an effect to see the studies behind its rating. Bars show the size of the effect; the letter grades the evidence.
Fitness3 effects
No study is linked to this rating.
No study is linked to this rating.
Energy2 effects
No study is linked to this rating.
No study is linked to this rating.
All studies
3 publications are linked to Leucine, newest first.