2-amino-5-guanidinopentanoic acid, Arg, arginine, arginine hydrochloride (intravenous formulation), dipeptide arginyl aspartate, HeartBars, ibuprofen-arginate, L-arg, L-arginine, NG-monomethyl-L-arginine, Sargenor, Spedifen®.
Note: Arginine vasopressin is different from arginine/L-arginine, with an entirely different mechanism. NG-monomethyl-L-arginine is different from arginine/L-arginine, and functions as an inhibitor of nitric oxide synthesis.
L-arginine was first isolated in 1886. In 1932, scientists learned that L-arginine is needed to create urea, a waste product that is necessary for toxic ammonia to be removed from the body. In 1939, researchers discovered that L-arginine is also needed to make creatine. Creatine breaks down into creatinine at a constant rate, and it is cleared from the body by the kidneys.
Arginine is considered a semi-essential amino acid because even though the body normally makes enough of it, supplementation is sometimes needed. For example, people with protein malnutrition, excessive ammonia production, excessive lysine intake, burns, infections, peritoneal dialysis, rapid growth, urea synthesis disorders, or sepsis may not have enough arginine. Symptoms of arginine deficiency include poor wound healing, hair loss, skin rash, constipation, and fatty liver.
Arginine changes into nitric oxide, which causes blood vessel relaxation (vasodilation). Early evidence suggests that arginine may help treat medical conditions that improve with vasodilation, such as chest pain, clogged arteries (called atherosclerosis), coronary artery disease, erectile dysfunction, heart failure, intermittent claudication/peripheral vascular disease, and blood vessel swelling that causes headaches (vascular headaches). Arginine also triggers the body to make protein and has been studied for wound healing, bodybuilding, enhancement of sperm production (spermatogenesis), and prevention of wasting in people with critical illnesses.
Arginine hydrochloride has a high chloride content and has been used to treat metabolic alkalosis. This use should be under the supervision of a qualified healthcare professional.
In general, most people do not need to take arginine supplements because the body usually produces enough.
Growth hormone reserve test / pituitary disorder diagnosis:
Arginine can be injected to measure growth hormone levels in people who might have growth hormone deficiencies, such as panhypopituitarism, gigantism, acromegaly, or pituitary adenoma. The U.S. Food and Drug Administration (FDA) has approved this use.
Inborn errors of urea synthesis:
In patients with inborn errors of urea synthesis, high ammonia levels in the blood and metabolic alkalosis may occur, particularly among patients with ornithine carbamoyl transferase (OCT) deficiencies or carbamoyl phosphate synthetase (CPS) deficiencies. Arginine may help treatment by shifting the way the body processes nitrogen. Arginine should be avoided in patients with hyperargininemia (high arginine levels). Other drugs, such as citrulline, sodium benzoate, or sodium phenylbutyrate, may have similar benefits. However, dialysis may be needed at first. This use of arginine should be supervised by a qualified healthcare professional.
Coronary artery disease / angina:
Early evidence from several studies suggests that arginine taken by mouth or by injection may improve exercise tolerance and blood flow in arteries of the heart. Benefits have been shown in some patients with coronary artery disease and chest pain (called angina). However, more research is needed to confirm these findings and to develop safe and effective doses.
Some studies suggest that arginine may be beneficial for people with critical or life-threatening illnesses when it is added to nutritional supplements. However, it is unclear what the specific role of arginine is in recovery. Because of the potential for harm, large doses of arginine should be avoided.
Studies of arginine in patients with chronic heart failure have shown mixed results. Some studies report improved exercise tolerance. Additional studies are needed to confirm these findings.
Peripheral vascular disease / claudication:
Intermittent claudication causes leg pain and tiredness because cholesterol plaques or clots develop in leg arteries and block blood flow. A small number of studies report that arginine therapy may improve walking distance in patients with claudication. Further research is needed.
Adrenoleukodystrophy (ALD) is a rare inherited metabolic disorder that is characterized by the loss of fatty coverings (myelin sheaths) on nerve fibers in the brain and progressive destruction of the adrenal glands. This condition results in dementia and adrenal failure. Injections of arginine may help manage this disorder, although most study results are inconclusive. Further research is needed to evaluate the use of arginine in ALD.
Early studies suggest that arginine may help treat chronic anal fissures, which are small tears that develop in the anus. Additional studies are needed.
Arginine has been studied in autonomic failure, a condition that may include low blood pressure, but the effect is unclear. Well-designed studies will help clarify this relationship.
It is unclear if arginine can help treat breast cancer patients. Results from early human studies are mixed. High-quality studies are needed.
Arginine may improve immune function and protein function in burn patients. Further research is needed before a conclusion can be drawn.
Early human studies suggest that arginine supplements may be beneficial for patients undergoing chemotherapy. Larger, high-quality studies are needed.
Chest pain (non-cardiac):
Small studies in humans suggest that arginine taken by mouth (not injected) may improve non-cardiac chest pain associated with esophageal motor disorders. Large, well-designed studies are needed.
Circulation problems (critical limb ischemia):
Early human studies suggest that intravenous arginine may increase blood flow in patients with critical limb ischemia. This condition occurs when blood flow to the arms and/or legs is blocked. Large, well-designed trials are needed.
Dental pain (ibuprofen arginate):
Some research suggests that ibuprofen-arginate (Spedifen®) may reduce pain after dental surgery faster or more effectively than ibuprofen (e.g., Motrin® or Advil®) alone. More research is needed in this area.
Diabetes (Type 1/Type 2):
Early studies in humans suggest that arginine supplements may decrease the severity of diabetes. Large, well-designed studies are needed to understand this relationship.
Early studies in humans suggest that arginine supplements may help the body fight some long-term complications of diabetes, including heart disease and nerve damage. Well-designed studies are needed.
Early studies have shown that arginine supplements may help treat erectile dysfunction (ED) in men with low nitrate levels in their blood or urine. A combination of L-arginine, glutamate, and yohimbine hydrochloride has been used to treat ED. However, because a combination product was used, and yohimbine hydrochloride is an FDA-approved therapy for this condition, the effects of arginine alone are unknown. More research is needed with arginine alone.
Gastrointestinal cancer surgery:
A combination of arginine and omega-3 fatty acids may reduce the length of hospital stays and infections after surgery in gastrointestinal cancer patients. Other research suggests that arginine, omega-3 fatty acids, and glutamine may boost the immune system and reduce inflammation after surgery. More research with arginine alone is needed.
Heart protection during coronary artery bypass grafting (CABG):
Arginine-supplemented "blood cardioplegic solution" may help protect the heart. Further research is needed before a firm conclusion can be drawn.
High blood pressure:
Early study in humans suggests that arginine taken by mouth may help widen the arteries and temporarily reduce blood pressure in patients with high blood pressure and type 2 diabetes. Larger, high-quality studies are needed before a recommendation can be made.
Some research suggests that arginine may help treat or prevent high cholesterol. More research is needed.
Early study results suggest that arginine supplementation may boost the immune response elicited by the pneumonia vaccine in older people. More studies are needed to confirm these results.
Intrauterine growth retardation:
Early studies in pregnant mothers suggest that arginine supplements may improve growth in fetuses that are smaller than average. Additional studies are needed.
Kidney disease or failure:
Study results are mixed as to whether arginine as a therapy by itself directly helps certain kidney diseases or failure. Arginine may be a helpful adjunct for kidney disease related conditions such as anemia in the elderly. Additional research is needed in this area.
Early studies have found that long-term supplementation with L-arginine significantly improved endothelial function in patients with MELAS syndrome (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke). Further research is merited in this area.
Myocardial infarction (heart attack):
Study results of arginine supplementation after myocardial infarction (heart attack) are mixed. Further research is needed before a recommendation can be made. A cardiologist and pharmacist should be consulted before arginine supplements are taken.
Pre-eclampsia (high blood pressure in pregnancy):
Early study suggests that long-term supplementation with L-arginine may decrease blood pressure that is too high in pregnant women. Arginine may also improve fetal health and growth during pre-eclampsia. Further research is needed to confirm these results.
Studies of arginine for pressure ulcers show mixed results. Further research is needed before a conclusion can be drawn.
Prevention of restenosis after coronary angioplasty (PTCA):
Arginine has been injected in patients who had stents surgically inserted into arteries in order to widen them. Early research suggests that this therapy may help prevent the arteries from becoming narrow again (called restenosis). Additional studies are needed.
Early study in humans has looked at the effect of arginine on blood vessel activity in Reynaud's phenomenon, a condition that causes the blood vessels in the fingers, toes, nose, and ears to narrow in response to cold temperatures or stress. However, the effects of arginine are not clear. Large, well-designed trials are needed.
Recovery after surgery:
Early study suggests that arginine may provide benefits when used as a supplement after surgery. However, the role of arginine in this condition is unclear. More research is needed to determine if this is safe and effective.
Early study suggests that arginine supplements may decrease the risk of respiratory (lung) infections. Large, well-controlled studies are needed to clarify this relationship.
There is not enough information available to make a strong recommendation about the use of arginine in senile dementia.
Dietary supplementation with L-arginine and canola oil has been associated with decreased rejection rates after the first month in kidney transplant patients. Because it may reduce the risk of heart problems, long-term benefits for patient survival may be particularly important. Further research is needed to confirm these results.
Arginine has been suggested to improve the rate of wound healing in the elderly. Research has shown that an enteral diet supplemented with arginine and fiber improved wound healing after surgery in patients with head and neck cancer. Arginine has also been applied to the skin in order to improve wound healing. Further research is necessary in this area before a firm conclusion can be drawn.
Animal studies report that arginine blocks the poisonous (toxic) effects of cyclosporine, a drug used to prevent organ transplant rejection. However, results from studies in humans have not found that arginine offers any protection from cyclosporine-induced toxicity.
Overall, currently available study results conclude that arginine supplementation does not improve exercise performance.
Although there are several studies in this area, it is not clear what effects arginine has on improving the likelihood of getting pregnant. Early evidence does not support the use of arginine as a fertility treatment in women who are undergoing in vitro fertilization or in men with abnormal sperm.
Arginine has been proposed as a treatment for interstitial cystitis or inflammation of the bladder. However, most human studies have not found that arginine improves symptoms, such as urinary frequency or urgency.
Kidney protection during angiography:
The contrast media, or dye, used during angiography to map a patient's arteries (or during some CT scans) can be poisonous (toxic) to the kidneys, especially among people with kidney disease. Researchers have studied L-arginine as a way to protect the kidneys in patients with long-term kidney failure who were undergoing angiography. The authors found no evidence that injections of L-arginine protect the kidney from damage due to contrast.
Although it has been suggested that arginine may treat asthma, studies in humans have actually found that arginine worsens inflammation in the lungs and contributes to asthma symptoms. Therefore, taking arginine by mouth or by inhalation is not recommended in people with asthma.