L-Arginine is essential to several systems in the body.

Among its many roles, L-Arginine:
 -Is a precursor of nitric oxide (NO)
 -Promotes circulation resulting in improved blood flow
 -Stimulates the release of growth hormone
 -Improves immune function
 -Reduces healing time of injuries
 -Plays a role in the formation of bone and tendons
 -Increases muscle mass, while reducing body fat
 -Supports male fertility, improving sperm production and motility
 -Reduces risk of blood clots and stroke
 -Supports normal blood pressure
 -Improves vascular function for patients with angina
 -Helps recovery after heart attack
 -Helps prevent and treat cardiovascular disease
 -Helps reduce growth of cancerous tumors

Both men and women report that L-Arginine seems to increase their libido or desire for sex, and some also report that L-Arginine gives them greater endurance and stronger, more powerful orgasms. Reports also suggest that L-Arginine supplements can improve fertility in men who have low sperm counts or poor sperm motility (activity).