L-Arginine is One of the NOBEL ingredient
By Cathy Wong, About.com (Updated: September 20, 2007)
About.com Health’s Disease and Condition content is reviewed by our Medical Review Board
What is L-Arginine?
L-arginine is an amino acid that has numerous functions in the body. It helps the body get rid of ammonia (a waste product), is used to make compounds in the body such creatine, L-glutamate, and L-proline, and can be converted to glucose and glycogen if needed.
L-arginine is used to make the nitric oxide, a compound in the body that relaxes blood vessels. Preliminary studies have found that L-arginine may help with conditions that improve when blood vessels are relaxed (called vasodilation), such as atherosclerosis, erectile dysfunction, and intermittent claudication.
L-arginine is also involved in protein formation. In larger amounts, L-arginine stimulates the release of hormones growth hormone and prolactin.
Why Do People Use L-Arginine?
· Heart disease
In the body, L-arginine is used to make nitric oxide, which reduces blood vessel stiffness, increases blood flow, and improves blood vessel function.
However, L-arginine should not be used following a heart attack. An study sponsored by the National Institutes of Health examining the use of L-arginine after a heart attack was terminated early after six patients died, a disproportionate number. There were no deaths in the patients who did not receive L-arginine.
The study researchers speculate that L-arginine may aggravate the effects of cardiac shock. The results were published in the Journal of the American Medical Association.
· Erectile Dysfunction
L-arginine has been used for erectile dysfunction. Like the drug sildenafil citrate (Viagra), L-arginine is thought to enhance the action of nitric oxide, which relaxes muscles surrounding blood vessels supplying the penis. As a result, blood vessels in the penis dilate, increasing blood flow, which helps maintain an erection. The difference in how they work is that Viagra blocks an enzyme called PDE5 which destroys nitric oxide and L-arginine is used to make nitric oxide.
In one study, 50 men with erectile dysfunction took either 5 grams of L-arginine per day or a placebo. After six weeks, more men in the L-arginine group had an improvement compared to those taking the placebo.
Unlike Viagra, L-arginine must be taken daily.
· Wound healing
L-arginine’s possible activity in wound repair may be due to its role in the formation of L-proline, an important amino acid that is essential for the synthesis of collagen.
· Other Conditions
L-arginine is also used for high blood pressure, migraines, sexual dysfunction in women, intermittent claudication, and interstitial cystitis.
Sources of L-Arginine
L-arginine is conditionally essential, which means that the body normally has enough. It’s produced in the kidney and to a lesser extent, in the liver.
Food sources of L-arginine include plant and animal proteins, such as dairy products, meat, poultry, fish, and nuts. The ratio of L-arginine to lysine is also important – soy and other plant proteins have more L-arginine than animal sources of protein.
Severe burns, infections, and injuries can deplete the body’s supply of arginine. Under these conditions, L-arginine becomes essential and it is necessary to ensure proper intake to meet the increased demands.
L-arginine is also essential for children with rare genetic disorders that impair the formation of L-arginine.
Side Effects of L-Arginine
L-arginine may lower blood pressure because it is involved in the formation of nitric oxide. It may also result in indigestion, nausea, and headache.
L-arginine should not be used following a heart attack. If you have a history of heart disease, consult your doctor before taking L-arginine.
Higher doses of arginine can increase stomach acid, so it may worsen heartburn, ulcers, or digestive upset cause by medications. Arginine appears to increase stomach acid by stimulating the production of gastrin, a hormone that increases stomach acid.
L-arginine may also alter potassium levels, especially in people with liver disease. People with kidney disease and those who take ACE inhibitors or potassium sparing diuretics should not use supplemental L-arginine unless they are under professional supervision. It may also alter the levels of other chemicals and electrolytes in the body, such as chloride, sodium, and phosphate.
Arginine may increase blood sugar levels, so it shouldn’t be used by people with diabetes unless under a doctor’s supervision.
Pregnant and nursing women and children should not use supplemental L-arginine, as it’s safety has not been established.
People with genital herpes should not take L-arginine because it may aggravate their symptoms.
Possible Drug Interactions
L-arginine may counteract the benefits of lysine to treat herpes
NSAIDS (non-steroidal anti-inflammatories) or other drugs that are hard on the stomach should not be combined with L-arginine.
Drugs that alter potassium levels in the body, such as ACE inhibitors and potassium sparing diuretics.
Schulman SP et al. “L-arginine therapy in acute myocardial infarction: the Vascular Interaction With Age in Myocardial Infarction (VINTAGE MI) randomized clinical trial”. JAMA. 295.1 (2006):58-64.