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L-Arginine

Health Benefits, Uses, Side Effects & Tips

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Updated February 25, 2014

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

L-arginine is an amino acid commonly sold in supplement form and obtained naturally in the diet. L-arginine-rich foods include plant and animal proteins, such as dairy products, meat, poultry, fish, and nuts.

Necessary for the production of protein, L-arginine also helps rid the body of ammonia (a waste product) and stimulates the release of insulin. In addition, L-arginine is used to make nitric oxide (a compound that relaxes the blood vessels). Although some studies suggest that L-arginine may benefit certain health conditions, other research shows that L-arginine may have harmful effects on some individuals.

Health Benefits of L-Arginine:

Studies indicate that L-arginine may help with the following conditions:

1) Angina

Several small studies show that increasing intake of foods high in L-arginine may help ease symptoms, increase exercise tolerance, and improve blood vessel function in people with angina.

Learn about other natural approaches to angina treatment.

2) Erectile Dysfunction

There's some evidence that L-arginine may benefit men with erectile dysfunction. In a 1999 study published in the journal BJU International, for instance, 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 showed improvement compared to those taking the placebo.

Like the drug sildenafil citrate (Viagra), L-arginine is thought to enhance the action of nitric oxide and—in turn—relax the muscles surrounding blood vessels supplying the penis. As a result, blood vessels in the penis dilate, increasing blood flow, which may help 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. Unlike Viagra, L-arginine is taken on a daily basis for erectile dysfunction.

This is just one remedy that is used for erectile dysfunction. To learn about others, read Natural Remedies for Erectile Dysfunction.

3) Congestive Heart Failure

L-arginine may improve cardiac performance in people with congestive heart failure, according to a 2000 study published in Clinical Cardiology. However, the National Institutes of Health (NIH) caution that L-arginine should not be used in place of standard treatments prescribed by a healthcare provider.

Other Common Uses for L-Arginine

Proponents claim that L-arginine can also benefit:

Some people also use L-arginine to boost the immune system, improve athletic performance, and shorten recovery time after surgery. L-arginine is also used for bodybuilding.

Studies show that L-arginine may be effective for managing inflammation of the bladder, relieving leg cramping and weakness caused by blocked arteries (a condition known as intermittent claudication), and improving kidney function in kidney transplant patients taking cyclosporine. What's more, taking L-arginine in combination with ribonucleic acid and eicosapentaenoic acid (an omega-3 fatty acid) may reduce recovery time, protect against infection, and promote wound healing after surgery.

According to the NIH, there's not yet enough evidence to rate the effectiveness of L-arginine in treatment of migraines, dementia, high blood pressure, male infertility, and the common cold. It's also unknown whether L-arginine can boost the immune system and/or improve athletic performance.

Additionally, L-arginine appears ineffective for prevention of heart attack and treatment of preeclampsia.

Side Effects

Although L-arginine may be safe when taken in the short term, it can cause a number of side effects (including indigestion, nausea, headache, bloating, diarrhea, gout, blood abnormalities, allergies, airway inflammation, worsening of asthma, and low blood pressure).

Higher doses of L-arginine can increase stomach acid, so it may also worsen heartburn, ulcers, or digestive upset caused by medications.

Due to safety concerns, L-arginine should be avoided by diabetes patients, people who have suffered a heart attack, and pregnant or nursing women.

In addition, L-arginine may aggravate symptoms in people with herpes.

Using L-Arginine For Health

In most cases, the body maintains an adequate supply of L-arginine on its own. However, severe burns, infections, and injuries can deplete the body's supply of arginine. Under these conditions, it is necessary to ensure proper intake to meet the increased demands.

If you're considering the use of L-arginine in treatment or prevention of a specific health condition, make sure to consult your doctor before taking any supplements.

Sources

Blum A, Porat R, Rosenschein U, Keren G, Roth A, Laniado S, Miller H. "Clinical and inflammatory effects of dietary L-arginine in patients with intractable angina pectoris." Am J Cardiol. 1999 May 15;83(10):1488-90, A8.

Bocchi EA, Vilella de Moraes AV, Esteves-Filho A, Bacal F, Auler JO, Carmona MJ, Bellotti G, Ramires AF. "L-arginine reduces heart rate and improves hemodynamics in severe congestive heart failure." Clin Cardiol. 2000 Mar;23(3):205-10.

Chen J, Wollman Y, Chernichovsky T, Iaina A, Sofer M, Matzkin H. "Effect of oral administration of high-dose nitric oxide donor L-arginine in men with organic erectile dysfunction: results of a double-blind, randomized, placebo-controlled study." BJU Int. 1999 Feb;83(3):269-73.

Maxwell AJ, Zapien MP, Pearce GL, MacCallum G, Stone PH. "Randomized trial of a medical food for the dietary management of chronic, stable angina." J Am Coll Cardiol. 2002 Jan 2;39(1):37-45.

National Institutes of Health. "L-arginine: MedlinePlus Supplements". November 2010.

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.

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