L-Arginine

The amino acid, arginine, has several roles in the organism. Arginine can assist in wound healing, help remove ammonia from the body, promote immune activity and assist in the secretion of several hormones including insulin, glucagon, and growth hormone.

Arginine increases protein synthesis which can lead to cellular replication. Thus, arginine could help people with inadequate numbers of certain cells.
For example, a few studies have found that men with low sperm count experienced an increase in the number of sperm with arginine consumption.

Arginine may also increase protein synthesis while improving wound healing. This effect has been shown in both animals and humans with high intake (17 grams per day).

Arginine is also a precursor to nitric oxide, which the organism uses to keep blood vessels dilated, allowing the heart to receive appropriate levels of oxygen. Clinicians have also started using arginine with people experiencing angina and congestive heart failure.

A few studies have shown evidence that arginine may help regulate cholesterol levels and appears to act as a natural blood thinner by reducing platelet aggregation.