Evidence

These uses have been tested in humans or animals.  Safety and effectiveness have not always been proven.  Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Key to grades

A
Strong scientific evidence for this use
B
Good scientific evidence for this use
C
Unclear scientific evidence for this use
D
Fair scientific evidence against this use (it may not work)
F
Strong scientific evidence against this use (it likely does not work)

Grading rationale

Evidence gradeCondition to which grade level applies
A

Growth hormone reserve test / pituitary disorder diagnosis (arginine hydrochloride)

Arginine is sometimes injected into a vein to measure growth hormone levels in people being tested for growth hormone deficiencies, such as panhypopituitarism, gigantism, acromegaly, or pituitary adenoma. The U.S. Food and Drug Administration (FDA) has approved this use.
A

Inborn errors of urea synthesis

People with inborn errors of urea synthesis may have high ammonia levels in the blood and metabolic alkalosis. There is strong evidence supporting the use of arginine for this condition. Arginine should be avoided in people with high arginine levels in the blood. A qualified healthcare professional should supervise use.
B

Heart disease

There is good scientific evidence that dietary supplementation with L-arginine may help people with coronary artery disease, angina, or clogged arteries, due to its effects on blood vessels. Larger, longer-term studies are needed to confirm these initial positive effects.
B

Heart failure

Arginine has been studied in people with heart failure. Longer-term studies are required to confirm the clinical benefit of L-arginine supplementation in people with heart disease.
B

Peripheral vascular disease / claudication

Peripheral vascular disease, also known as intermittent claudication, is a narrowing of blood vessels in the legs and feet caused by fatty deposits. This condition causes decreased blood flow to the legs and feet, resulting in leg pain and tiredness. A small number of studies report that arginine therapy may improve walking distance in people with claudication. Further research is needed.
C

Adrenoleukodystrophy (ALD)

Adrenoleukodystrophy (ALD) is a rare inherited metabolic disorder that involves damage to the nerves in the brain and the adrenal glands. This condition results in dementia and adrenal failure. Arginine injections may help manage this disorder; however, most study results are inconclusive. Further research is needed to evaluate the use of arginine in ALD.
C

Altitude sickness

Limited research has examined the effect of L-arginine on altitude sickness symptoms. Larger, well-designed trials are required before conclusions can be made.
C

Anal fissures

Early research suggests that arginine helps heal chronic anal fissures, which are small tears that develop in the anus. Additional studies are needed.
C

Anxiety

In limited research, the combination of L-lysine and L-arginine reduced symptoms of anxiety. The effect of L-arginine alone is unknown. Additional research is needed in this area.
C

Autonomic failure

Arginine has been studied for treating autonomic failure, a condition that may include low blood pressure. Its effect is unclear. Well-designed studies are needed.
C

Birth outcomes

The effect of L-arginine on birth outcomes has been studied. Additional research is needed before conclusions can be made.
C

Blood flow enhancement

In limited research, L-arginine increased blood flow. Because of conflicting results from one study, additional research is needed.
C

Breast cancer

The therapeutic effect of arginine on breast cancer is unclear. Results from early human studies are mixed. High-quality studies are needed.
C

Burns

Arginine may improve immune function and protein function in burns . Further research is needed before a conclusion can be drawn.
C

Cachexia (weight loss and muscle-wasting)

A combination of beta-hydroxyl beta-methyl butyrate, glutamine, and arginine has been tested in people with cachexia associated with cancer, but conclusions could not be drawn. Further research is needed.
C

Chemotherapy

Early human studies suggest that arginine supplements may benefit people undergoing chemotherapy. Larger, high-quality studies are needed.
C

Chest pain

Limited human research reported that arginine taken by mouth improved chest pain in people with esophagus problems. Large, well-designed studies are needed.
C

Cognitive function

In early research, L-arginine increased cognitive function in elderly people with cerebrovascular disease (problems with blood vessels in the brain). Better-designed studies are needed.
C

Critical illness

The impact of L-arginine supplementation on critical illness is unclear. Further research is needed.
C

Cyclosporine toxicity

Results of early studies of the effect of L-arginine on cyclosporine toxicity in renal transplant are mixed. Additional research is needed in this area.
C

Dental conditions

In early research, arginine-containing toothpaste has reduced tooth sensitivity. An arginine-containing product was also effective in reducing dental caries. Additional research is needed to confirm these effects.
C

Diabetes (type 2)

The effect of L-arginine on type 2 diabetes has been investigated. Large, well-designed studies are needed to understand the effect of arginine on type 2 diabetes.
C

Diabetic complications

Early research indicates that L-arginine may play a role in reducing complications associated with diabetes. However, further research is required before conclusions can be made.
C

Erectile dysfunction

Early studies showed that arginine supplements helped treat erectile dysfunction (ED) in men with low nitrate or nitrite levels in their blood or urine. A combination of L-arginine, glutamate, and yohimbine hydrochloride was 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 are unknown. More research is needed with arginine alone.
C

Exercise performance

Despite common use by athletes, the effect of arginine for exercise performance enhancement has not been studied extensively. Well-designed studies investigating arginine alone are needed before conclusions can be made.
C

Fetal development

Preliminary research of pregnant mothers suggests that arginine supplements improve growth in smaller-than-average fetuses. Additional studies are needed.
C

Gastrointestinal cancer surgery

A combination of arginine, RNA, and omega-3 fatty acids may reduce the length of hospital stay and infections after surgery for gastrointestinal cancer. More research with arginine alone is needed.
C

Heart protection during coronary artery bypass grafting (CABG)

An arginine-supplemented blood solution used during surgery may help protect the heart in people undergoing coronary artery bypass grafting. Further research is needed before a firm conclusion can be drawn.
C

High blood pressure

Early research reported that arginine taken by mouth reduced blood pressure in people with high blood pressure. Larger, high-quality studies are needed before a conclusion can be made.
C

High cholesterol

Some research suggests that arginine may help treat high cholesterol. However, results are conflicting and more research is needed.
C

Immune function

L-arginine has immune effects in people undergoing surgery for colorectal cancer and in children with airway infections. In HIV, L-arginine in combination with omega-3 fatty acids and a nutritional supplement had no additional effects on immune response over a nutritional supplement alone. Additional well-designed research is needed.
C

Infertility

Limited research has investigated the effect of L-arginine on male and female infertility. Further research is required before conclusions can be made.
C

MELAS syndrome

Early studies found that supplementation with L-arginine significantly improved endothelial function in people with MELAS syndrome (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke). Further research is needed in this area.
C

Metabolic disorders

Limited research suggests that L-arginine may decrease symptoms associated with creatine deficiency syndromes. Further research is required before conclusions can be drawn.
C

Polycystic ovarian syndrome

In early research, treatment with N-acetyl cysteine (NAC) and L-arginine restored some function in people with polycystic ovary syndrome. Further research is required before conclusions can be drawn.
C

Pre-eclampsia (high blood pressure in pregnancy)

Effects of L-arginine in women with pre-eclampsia are mixed. Longer-term treatment appeared to be more effective than short-term treatment. Further research is needed before a conclusion can be made.
C

Pressure ulcers

Studies of arginine for pressure ulcers show mixed results. Further research is needed before a conclusion can be drawn.
C

Prevention of restenosis after coronary angioplasty (PTCA)

Injection of L-arginine into surgically placed stents was investigated with mixed results. Early research suggested that L-arginine may or may not prevent restenosis (narrowing) in the arteries. Further well-designed studies are required.
C

Raynaud's phenomenon

Early research in humans investigated the effect of arginine on blood vessel activity in Raynaud's phenomenon, a condition causing 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 unclear. Large, well-designed trials are needed.
C

Recovery after surgery

In early research, arginine combined with other supplements helped recovery after surgery. However, the role of arginine alone is unclear. More research is needed in this area.
C

Respiratory infections

Early research suggests that arginine supplements may decrease the risk of respiratory (lung) infections. Large, well-controlled studies are needed to clarify this relationship.
C

Scleroderma

In early research, L-arginine may be useful for pregnant women with scleroderma (buildup of scar tissue in the skin). Further research is needed in this area.
C

Sickle cell anemia

Clinical studies investigating the effects of L-arginine on sickle cell anemia are limited. Early research suggests the potential for immune benefits. Further research is needed in this field.
C

Transplants

In human research, L-arginine improved kidney function in people with a kidney transplant, and improved quality of life and exercise tolerance in people with heart transplants. Additional clinical research is needed.
C

Uterine disorders

In early research, L-arginine improved endometrial thickness in people with a thin endometrium (the lining of the uterus). Further studies are required before conclusions can be drawn.
D

Asthma

Early research has suggested a lack of benefit in the use of arginine for asthma.
D

Interstitial cystitis

Arginine has been proposed as a treatment for interstitial cystitis (inflammation of the bladder). However, most studies found a lack of effect.
D

Kidney disease or failure

Overall evidence from early research fails to support the use of L-arginine for kidney disease or failure. Until the evidence is more consistent, conclusions cannot be made.
D

Kidney protection during angiography

The contrast media, or dye, used during angiography to map arteries may be poisonous (toxic) to the kidneys, especially in people with kidney disease. Early researcher has found a lack of evidence that injections of L-arginine protected the kidney from damage due to contrast agents.
D

Wound healing

In human research, arginine appeared to lack benefit in wound healing. Further research is required before conclusions can be made.
F

Myocardial infarction (heart attack)

Until potential safety issues are addressed, L-arginine should be avoided in people having a heart attack.

Uses based on tradition or theory

The below uses are based on tradition or scientific theories. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Aging, AIDS/HIV, ammonia toxicity, amyotrophic lateral sclerosis (ALS), antibacterial, anti-inflammatory, antioxidant, anti-platelet agent, beta-hemoglobinopathies (blood disorder), cancer, cirrhosis, cold prevention, cystic fibrosis, depression, epilepsy, eye disorders, food uses, glaucoma, growth, gut disorders, heavy metal/lead toxicity, hemolytic uremic syndrome (blood disorder), hepatic encephalopathy (confused thinking due to liver disorders), hyperhomocysteinemia (high homocysteine in the blood), increased muscle mass, inflammatory bowel disease (IBD), liver disease, liver protection, lower esophageal sphincter relaxation, malaria, metabolic acidosis, migraine, mitochondrial disorders, neurological problems, obesity/weight loss, osteoporosis / osteopenia, pain, parasites, peritonitis (inflammation of the stomach lining), Peyronie's disease (abnormal curvature and scar tissue in the penis), pre-term labor contractions, pruritus (itching), rabies, sexual function in women, stomach motility disorders, stomach ulcers, stress, stroke, supplementation to a low protein diet, thrombotic thrombocytopenic purpura (blood disorder), trauma, ulcerative colitis, vaccine adjunct, vascular disorders.

This evidence-based monograph was prepared by The Natural Standard Research Collaboration

www.naturalstandard.com