Leucine metabolite
HMB
Limited evidenceA breakdown product of leucine, studied for preserving muscle.
What it is
HMB (beta-hydroxy-beta-methylbutyrate) is made in the body when leucine is broken down.
Food sources
Made from dietary leucine (small amounts)
What the research shows
- Results are mixed. Benefits appear more likely in untrained people and older adults than in trained athletes.
Read the published research on PubMed →
Food first: most people get what they need from a varied diet with enough total protein. Talk to a provider or registered dietitian before adding a supplement, especially if you take medication or have a health condition.
Similar evidence level
Conditionally essential amino acid
Arginine
A precursor to nitric oxide, though oral supplements are poorly absorbed for that purpose.
Limited evidenceConditionally essential amino acidGlutamine
The most abundant amino acid in the blood, often oversold for muscle recovery.
Limited evidenceNonessential amino acidGlycine
The simplest amino acid, a major part of collagen, and studied for sleep.
Limited evidence