Erectile Dysfunction and L-Arginine
L-arginine (arginine) is an amino acid found in many foods, including dairy products, meat, poultry, and fish. It plays a role in several important processes in the body, including cell division, wound healing, removal of ammonia from the body, immunity to illness, and the secretion of hormones. The body uses arginine to make nitric oxide (NO), a substance that relaxes blood vessels and also exerts numerous other effects in the body. The connection between arginine and NO is the reason why arginine supplements might be helpful in treating erectile dysfunction.
Effect of L-Arginine on Erectile Dysfunction
The substance nitric oxide (NO) plays a role in the development of an erection. Drugs like Viagra make the body more sensitive to the natural rise in NO that occurs with sexual stimulation. A simpler approach might be to raise NO levels, and one way to accomplish this involves use of the amino acid L-arginine. Oral arginine supplements may increase nitric oxide levels in the penis and elsewhere. Based on this, L-arginine has been advertised as "natural Viagra." However, there is not yet much evidence that it works. Drugs based on raising nitric oxide levels in the penis have not worked out for pharmaceutical developers; the body seems to simply adjust to the higher levels of NO and maintain the same level of response.
Research Evidence on L-Arginine
The best evidence for the use of arginine in erectile dysfunction comes from a small double-blind trial in which 50 men with erectile dysfunction received either 5 g of L-arginine or placebo daily for 6 weeks.1 More of the men who took the arginine saw improvement in sexual performance than the men who took the placebo.
A double-blind crossover study of 32 men found no benefit with 1,500 mg of arginine given daily for 17 days2; the much smaller dose and shorter course of treatment may explain why arginine appeared less effective in this trial.
Arginine has also been tested in combination with the drug yohimbine (made from the herb yohimbe)3. A double-blind, placebo-controlled trial of 45 men found that one-time use of this combination therapy an hour or two before intercourse improved erectile function, especially in those with only moderate erectile dysfunction scores. Arginine and yohimbine were both taken at a dose of 6 g.
Weak evidence suggests that oligomeric proanthocyanidin complexes (OPCs)--alone or in combination with arginine--may be a useful treatment for erectile dysfunction.4, 5
Side Effects and Warnings
Do not use the drug yohimbine (or the herb yohimbe) except under physician supervision, as it presents a number of safety risks.
- Chen J, Wollman Y, Chernichovsky T, et al. 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;83:269-273.
- Klotz T, Mathers MJ, Braun M, et al. Effectiveness of oral L-arginine in first-line treatment of erectile dysfunction in a controlled crossover study. Urol Int. 1999;63:220-223.
- Lebret T, Herve JM, Gorny P, et al. Efficacy and safety of a novel combination of L-arginine glutamate and yohimbine hydrochloride: a new oral therapy for erectile dysfunction. Eur Urol. 2002;41:608-613
- Durackova Z, Trebaticky B, Novotny V, et al. Lipid metabolism and erectile function improvement by pycnogenol extract from the bark of Pinus pinaster in patients suffering from erectile dysfunction-a pilot study. Nutr Res. 2003;23:1189-1198.
- Stanislavov R, Nikolova V. Treatment of erectile dysfunction with pycnogenol and L-arginine. J Sex Marital Ther. 2003;29:207-213.
- Ito T, Kawahara K, Das A. A double-blind placebo-controlled study on the effects of ArginMax, a natural nutritional supplement for enhancement of male sexual function. ArginMax website. Available at: http://www.arginmax.com/html/abstract.htm. Accessed October 5, 2005.