- What is L-arginine? L-arginine (or arginine) is an amino acid that is necessary for the body's production of nitric oxide, a compound that relaxes blood vessels and allows more blood to flow through arteries. The form in supplements is typically "free form" arginine, but is sometimes a compound, such as L-arginine HCl. (See What It Is). Not all labels clearly list the amount of arginine. (See What to Consider When Buying), but you can use the Results table to easily compare amounts of arginine in tested supplements.
- What are the health benefits of L-arginine? L-arginine may modestly improve symptoms of congestive heart failure, exercise intolerance in people with angina, and leg pain due to intermittent claudication, as well as exercise endurance in recreational and older athletes. However, it does not appear to improve blood flow to muscle or athletic performance in athletically active young adults. Some, but not all, studies have shown some modest benefits in sexual dysfunction and Raynaud's syndrome. L-arginine can provide nutritional support and stimulate the immune system in some people with cancer. It may also improve chemotherapy response rate and slow the growth of certain breast and colon tumors, but be aware it may actually promote the growth of others (See What It Does).
- How much L-arginine to take? Dosage depends on the condition being treated, but is typically several thousand milligrams per day (See Dosage).
- Best L-arginine products? Among the products that passed our laboratory tests (See What CL Found), we selected Top Picks for arginine for general use, cardiovascular, sexual enhancement, and sport.
- L-arginine safety and side effects: L-arginine supplementation appears to be generally safe and well tolerated in healthy individuals, although stomach upset may occur, and capsules have been reported to irritate the esophagus — so be sure to take with water. L-arginine may interact with blood-pressure lowering and diabetes medications. Do not use if you have had a heart attack, and do not use to treat serious conditions including congestive heart failure, angina, or intermittent claudication without physician supervision. For details, see Concerns and Cautions.