L-histidine is the L-enantiomer of the amino acid histidine. It has a role as a nutraceutical, a micronutrient, a Saccharomyces cerevisiae metabolite, an Escherichia coli metabolite, a human metabolite, an algal metabolite and a mouse metabolite. It is a proteinogenic amino acid, a histidine and a L-alpha-amino acid. It is a conjugate base of a L-histidinium(1+). It is a conjugate acid of a L-histidinate(1-). It is an enantiomer of a D-histidine. It is a tautomer of a L-histidine zwitterion.