Amino acid arginine is an essential amino acid and is present in the proteins of all life forms. It is classified as a conditionally essential or semi-essential amino acid because under normal conditions the body can produce sufficient quantities of amino acid arginine to meet physiological demands. However, in times of stress conditions such as wound healing and trauma, the body might not be able to manufacture enough. In these cases, amino acid arginine becomes essential and is very important to ensure sufficient dietary intake of the amino acid to meet the increased physiological demands shaped by these conditions.
Amino acid arginine although not an essential amino acid, is a vital one. In addition to contributing to protein synthesis, it plays a number of other important roles in the body. Amino acid arginine’s primary function entails the metabolism of proteins and nitrogen. It also detoxifies ammonia formed during nitrogen catabolism of amino acids through the formation of urea. It is also a forerunner in the formation of polyamines, creatine, nitric oxide, proline, glutamate, agmatin, and the arginine-containing tetrapeptide tuftsin which is believed to be an immunomodulator. Amino acid arginine is also a glycogenic amino acid. If needed by the body, it can be converted to D-glucose and glycogen or can be catabolized to manufacture biological energy.
Arginine when taken in high doses stimulates the pituitary release of growth hormones, prolactin, and pancreatic release of glucagon and insulin. It is also used as an immunonutrient in parenteral and enteral nutrition to aid the improvement of the immune status of those suffering from burns, sepsis, and trauma.
Arginine is predominately manufactured in the kidney. It is a main intermediary in the Krebs-Henseleit urea cycle. A much smaller amount of this amino acid is synthesized in the liver. The normal dietary intake of arginine is 3.5 to 5 grams daily and most dietary arginine comes from animal and plant proteins. Arginine of small amounts can be found in vegetable juices and fermented foods, such as yogurt and miso. Plant proteins such as soy proteins and other plant proteins are richer in arginine than animal proteins which are richer in lycine. Arginine can also be found in dairy products, meat, poultry, nuts, fish, and chocolate. Other natural sources of arginine are brown rice, raisins, popcorn, and whole-wheat products.
Arginine has a maximum potential in preventing or reducing cardiovascular diseases, by stimulating a compound that relaxes the blood vessels called nitric oxide. It is also used to enhance memory, eliminate depression, improve sleep, control stress, prevent aging, relieve arthritis, manage allergies, promote hair growth, cure impotence, fight cancer, reduce herpes, combat fatigue, and stimulate the immune system. The normal supplemental dosage of arginine per day is 2 to 8 grams.