Histidine is an essential amino acid that plays a crucial role in the human body. It is involved in the synthesis of various metabolic enzymes and proteins. Histidine is often referred to as "L-histidine" or simply "His." Some other synonyms for histidine include 2-amino-3-(1H-imidazol-4-yl)propanoic acid, imidazolealanine, and histidinum. Histidine is found in a variety of foods, including eggs, meat, fish, and dairy products. The amino acid is also used in the food industry as a flavor enhancer and as a nutritional supplement for athletes and bodybuilders. Histidine supplementation may help improve athletic performance and support the immune system.