Amino acids
12 amino acids and derivatives, ranked by strength of evidence.
Beta-alanine
Raises muscle carnosine, a buffer against acid buildup during hard efforts.
Strong evidenceMade by the body from amino acidsCreatine
The most researched sports supplement, built from three amino acids.
Strong evidenceNonessential amino acidCitrulline
Converted to arginine in the body, and studied for exercise performance.
Moderate evidenceHydrolyzed proteinCollagen peptides
Collagen broken into small peptides. Popular, but not a complete protein.
Moderate evidenceEssential amino acid (BCAA)Leucine
The amino acid that acts as the main "on switch" for muscle protein building.
Moderate evidenceConditionally essential amino acidArginine
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 evidenceLeucine metaboliteHMB
A breakdown product of leucine, studied for preserving muscle.
Limited evidenceMade by the body from amino acidsL-carnitine
Shuttles fat into mitochondria, though supplements rarely move the needle for fat loss.
Limited evidenceNonessential amino acidTyrosine
A building block for dopamine and norepinephrine, studied under acute stress.
Limited evidenceConditionally essential amino acidTaurine
Abundant in heart, muscle, and brain, and a recent focus of aging research.
Early research