Arginine is an amino acid that plays a crucial role in various bodily functions. It is classified as a semi-essential amino acid, meaning that while the body can produce it, additional amounts may be needed during times of stress or illness. Arginine is important for protein synthesis, and it helps in the production of nitric oxide, a molecule that relaxes blood vessels and improves blood flow. In addition to its role in circulation, arginine is involved in the immune system and hormone regulation. It can be found in various foods, including meat, dairy products, nuts, and seeds. Some people also take arginine supplements to support athletic performance and recovery.