L-arginine belongs to an unusual class of nutrient known as conditionally nonessential amino acids. Nonessential amino acids are nutrients generally produced by the body in large enough amounts to meet its needs, but in special circumstances they may be needed from dietary sources as well. Dietary L-arginine is required most commonly for recovery from severe traumatic injury. In this instance, a large L-arginine dosage is required to help produce the building blocks of the tissues that need to be repaired. When used for conditions like the treatment of hypertension, erectile dysfunction, pre-eclampsia or cirrhosis of the liver, it is believed that the use of a much lower L-arginine dosage is sufficient.
Due to its role in the synthesis and maintenance of both bone and soft tissue, a high L-arginine dosage is sometimes used to speed the healing of traumatic injury. It is not recommended that the supplement be used after suffering injury to the heart muscle, though. There has been one report of increased mortality among patients receiving a large L-arginine dosage following a heart attack.
Some practitioners recommend the use of L-arginine for the treatment of erectile dysfunction in men and some types of sexual dysfunction in women due to its role in the synthesis of nitric oxide. Other popular pharmaceutical treatments for erectile dysfunction, such as Viagra®, also work through the manipulation of the nitric oxide pathway in the body. Unfortunately, few studies have substantiated these claims. Although some research has suggested that as many as five percent of patients receiving L-arginine for 30 days were successfully treated for impotence, this number was only slightly higher than patients receiving a placebo.
The compound is also the subject of research as a possible treatment for a wide variety of medical conditions. It is possible that the maleate salt of the amino acid may be helpful in the treatment of cirrhosis of the liver and alcoholic hepatitis as well as sepsis and Melas syndrome. When an antioxidant vitamin and L-arginine supplement regimen is followed during the end of pregnancy, the combination may help to address pre-eclampsia. Neither the efficacy nor the appropriate L-arginine dosage level for these conditions has been established.
Caution should be used when considering the use of supplemental L-arginine by patients who suffer from frequent cold sores, fever blisters, or breakouts of genital herpes. One factor that is believed to affect the activity of the herpes class of virus in the body is the ratio of L-arginine to L-lysine in the bloodstream. Since elevated levels of serum L-arginine alone may increase the frequency of outbreaks in infected patients, it may be advantageous to include an equivalent amount of L-lysine into their dietary supplement regimen.