Definition: L-Arginine (hereinafter called arginine) is an amino acid synthesized by humans and is also present in the diet.

• In addition to serving as a building block for protein synthesis, arginine is a precursor to nitric oxide, which functions as a vasodilator.
• Arginine also plays a role in Adverse effects of wound healing and enhances immune function.
• As a precursor to ornithine, arginine is involved in the urea cycle and therefore plays an important role in ammonia detoxification.
• Arginine has been reported to promote the release of growth hormone from the pituitary.
• Certain food-processing methods result in the destruction of significant amounts of arginine. These include heating of protein in the presence of reducing sugar (such as glucose, fructose, or lactose, as in the baking of bread) and alkali treatment of proteins (as in the manufacturing of textured vegetable protein).
• Arginine may be useful for preventing and/or treating anal fissures, congestive heart failure, erectile dysfunction, esophageal spasm, infertility, interstitial cystitis, and Raynaud’s disease/phenomenon.
• Lysine has been reported to antagonize arginine by several different mechanisms. As a possible lysine antagonist, arginine has the potential to interfere with the anti-herpetic effect of lysine or to provoke outbreaks of herpes simplex infection. Such an effect has been reported anecdotally but has not been investigated scientifically.
• Although nitric oxide produced from L-arginine has a number of beneficial effects on the cardiovascular system, it is also a highly unstable molecule that promotes the formation of reactive oxidants such as peroxynitrite. Peroxynitrite and other nitric oxide-derived oxidants are inflammatory mediators that may promote the development of atherosclerosis. The dual effects of nitric oxide are analogous to those of oxygen, which is both essential for life and toxic to cells (through the formation of oxygen-derived free radicals). Just as the body possesses various antioxidant defenses to protect against oxygen-derived free radicals, so does it have mechanisms to detoxify nitric oxide-derived oxidants. The substance that has been shown most clearly to scavenge reactive nitrogen species is gamma-tocopherol (1 of the 4 naturally occurring forms of vitamin E).

Food sources

• Good sources of arginine include meat, poultry, fish, dairy products, nuts, seeds, peanuts, whole grains, legumes, and chocolate.

Dosage and administration

• The dosage of arginine used in most clinical trials has ranged from 1.5–9.0 g/day, although larger doses have been used in some instances.