tst 11 L-Arginine is a non-essential amino acid that acts as a precursor of nitric oxide. Nitric oxide is necessary to increase blood flow and help blood circulation throughout the body. This effect is important for both men and women with respect to normal sexual function.L-Arginine works by increasing the flow of blood to the erectile tissues. It helps to dilate the blood vessels in the penis and helps the penis to expand to its maximum capacity. These male enhancement properties increase the size, hardness and frequency of erections in men. Studies also show that L-arginine can improve fertility in men who have low sperm counts and poor sperm motility.