Histidine is 1 of the 9 essential amino acids people must get from food. It is in most protein-rich foods such as meat, fish, and eggs. It is also in soy, whole grains, beans, and nuts. It's used in growth, repair of damaged tissues, and making blood cells.
D-Histidine is an optically active, D-configuration form of the amino acid histidine. It is an enantiomer of L-histidine, and is a metabolite in Saccharomyces cerevisiae.