Alanine is one of the 20 most common natural amino acids. It is hydrophobic, with a methyl group side chain, and is the second-smallest of the 20 after glycine. Alanine is a non-essential amino acid and was first isolated in 1879.

L-Alanine is synthesized in muscle cells from pyruvate by transamination, with glutamate as the nitrogen donor. In the liver, alanine is transformed into pyruvate by the reverse reaction.